Orthodontic Cephalometry

ORTHODONTIC
CEPHALOMETRY
Edited by
Athanasios E Athanasiou
DDS, MSD, DR DENT
Associate Professor
Department of Orthodontics
School of Dentistry
Aristotle University of Thessaloniki
Greece
> Formerly Associate Professor and Director

Postgraduate Orthodontic Education
Royal Dental College
Faculty of Health Sciences
University of Aarhus
Denmark
M Mosby-Wolfe
Lcnjon Baltimore Bogota Boston Buenos Aires Caracas Carlsbad. CA Chicago Madrid Mexico City Mil; - i-l New York PWadelphia Si. Lous Sydney Tokyo Toronto Wiesbaden
CONTENTS
List of Contributors 5
Preface and Acknowledgments 7
1. The Technique of Cephalometric Radiography 9

Smorntree Viteporn
2. Anatomy, Radiographic Anatomy and Ccphalometric Landmarks

of Craniofacial Skeleton, Soft Tissue Profile, Dentition, Pharynx
and Cervical Vertebrae 21
Smorntree Viteporn and Athanasios E Athanasiou
3. Possibilities and Limitations of Various Cephalometric Variables

and Analyses 63
Rainer-Reginald Miethke
4. Cephalometric Methods for Assessment of Dentofacial Changes 105

Samir E Bishara and Athanasios E Athanasiou
5. Sources of Error in Lateral Cephalometry 125

Vincenzo Maori and Athanasios E Athanasiou
6. Posteroanterior (Frontal) Cephalometry 141

Athanasios E Athanasiou and Aart JW van der Meij
7. Applications and Limitations of Cephalometry in Diagnosis and

Treatment Evaluation in Orthodontics 163
Louis A Norton, Sam Weinstein and Joo-Yeun him
8. Finding Pathology on Cephalometric Radiographs 175

Andrew J Kuhlberg and Louis A Norton
9. Clinical Research Applications of Cephalometry 181

Birte Melsen and Sheldon Baumrind
10. Cephalometric Assessment of Craniocervical Angulation,
Pharyngeal Relationships, Soft Palate Dimensions, Hyoid
Bone and Tongue Positions 203
Athanasios E Athanasiou, Moscbos Papadopoulos,
Michael Lagoudakis and Patios Goumas
11. Aspects of Digital Computed Radiography with Cephalometric

Applications 221
Alberto Barenghi, Evangelista G Mancini and Antonino Salvato
12. Computerized Cephalometric Systems 231

Athanasios E Athanasiou and ]ens Kragskov
13. Landmarks, Variables and Norms of Various Numerical

Cephalometric Analyses - Cephalometric Morphologic and
Growth Data References 241
Carles Bosch and Athanasios E Athanasiou
Index 293
LIST OF CONTRIBUTORS
Alberto Barenghi, MD, DDS Michael Lagoudakis, DDS
Visiting Professor Resident
Department of Orthodontics Department of Orthodontics
St Raphael Hospital Royal Dental College
University of Milan Faculty of Health Sciences
Milan, Italy University of Aarhus
Aarhus, Denmark
Sheldon Baumrind, DDS, MS
Professor Joo-Yeun Lim, DDS, MS
Department of Growth and Development Associate Clinical Professor,
Head Department of Orthodontics
Craniofacial Research Instrumentation School of Dentistry
Laboratory New York University
School of Dentistry New York, USA
University of California
San Francisco, California, USA Vincenzo Macri, MD, DDS, MS, DDO
Orthodontist
Samir E Bishara, DDS, MS Vicenza, Italy
Professor
Department of Orthodontics Evangcltsta G Mancini, MD, DDS
College of Dentistry Visiting Professor
University of Iowa Department of Orthodontics
Iowa City, Iowa, USA St Raphael Hospital
University of Milan
Carles Bosch, MD, DDS, MS Milan, Italy
Assistant Professor
Department of Orthodontics Birtc Melsen, DDS, Dr Odont
Royal Dental College Professor and Head
Faculty of Health Sciences Department of Orthodontics
University of Aarhus Royal Dental College
Aarhus, Denmark Faculty of Health Sciences
Panos Goumas, MD, DDS, Dr Med Aarhus, Denmark
Associate Professor and Head
Department of Otolaryngology Aart JW van dcr Meij, DDS
University Hospital of Patras Resident
School of Medicine Department of Orthodontics
University of Patras Royal Dental College
Patras, Greece Faculty of Health Sciences
Jens Kragskov, DDS, PhD Aarhus, Denmark
Department of Neuroradiology
University of Aarhus Hospital Raincr-Reginald Miethke, DDS, MD,
Aarhus, Denmark Dr Med Dent, PhD
Professor and Head
Andrew J Kuhlbcrg, DMD, MDS Department of Orthodontics
Assistant Professor Centre of Dental Medicine
Department of Pediatric Dentistry and Charite University Clinic
Orthodontics Humboldt University of Berlin
School of Dental Medicine Berlin, Germany
University of Connecticut
Farmington, Connecticut, USA
5
Louis A Norton, DMD Antonino Salvato, MD, DDS
Professor and Graduate Orthodontic Program's Professor and Head
Director Department of Orthodontics
Department of Pediatric Dentistry and St Raphael Hospital
Orthodontics University of Milan
School of Dental Medicine Milan, Italy
Farmington, Connecticut, USA Smorntree Viteporn, DDS, MDSc
Associate Professor
Moschos Papadopoulos, DDS, Dr Mcd Dent Department of Orthodontics
Lecturer Faculty of Dentistry
Department of Orthodontics Chulalongkorn University
School of Dentistry Bangkok, Thailand
Aristotle University of Thessaloniki
Thessaloniki, Greece
Sam Wcinstein, DDS, MS

Professor Emeritus
Department of Pediatric Dentistry and Orthodontics
School of Dental Medicine
Farmington, Connecticut, USA
6
PREFACE AND ACKNOWLEDGMENTS
Since its introduction in 1931 by Broadbent and Hofrath in the United States and Germany,
respectively, radiographic ccphalometry has become one of the most important tools of clinical and
research orthodontics. It is not an exaggeration to say that significant progress in the understanding
of craniofacial growth and development, and important innovations in orthodontic diagnosis and
treatment, have been achieved thanks mainly to the application, study and interpretation of cephalo-
grams.
The aim of this book is to provide a comprehensive presentation of the most important
theoretical and practical aspects of cephalometric radiography. Applications of the information
contained within it can be made in both clinical and research orthodontic environments. The book
constitutes a starting point for the newcomer to the field of cephalometry, but is also an 'all-inclusive'
reference source for academics, researchers and clinicians.
The book contains information and concepts based only on sound scientific evidence, supported
by credible and specific literature. For the sake of originality, several figures from classical and well
known cephalometric works have been reproduced in the text by the kind and generous permission
of the copyright owners. The editor and contributors would like to express their gratitude to all those
who gave permission for the reproduction of illustrations. Credits are given under each figure
accordingly.
A collective acknowledgment is also given to all those researchers, teachers and clinicians
throughout the world who have provided our profession with their invaluable experience, and whose
important contributions to the field of cephalometric radiography have enabled patient care to
progress to a more rigorous scientific level.
The book was written with the help of many people whose expertise was necessary in order to
properly present, address and discuss the various topics included. The editor is very much indebted
to all the contributors for their enthusiastic acceptance of his invitation to participate in the project
and their excellent collaboration. Special thanks also go to the publishers, Mosby-Wolfe.
The result of this effort is a work that deals with the following subjects, chapter by chapter:
Chapter 1 reviews contemporary radiological technical aspects, addresses imporrant considerations

for the quality control of radiographic images, and provides guidelines for protection from radiation.
Chapter 2 constitutes a comprehensive and systematic presentation of all anatomical structures of

the skull, radiographic images of which are used to identify the various cephalometric landmarks.
All osseous, dental and soft tissue structures are illustrated and described by means of anatomical
diagrams and radiographic anatomical imaging. Cephalometric landmarks are also identified in
tracings of all the important regions and structures of the skull.
Chapter 3 provides an exhaustive discussion of the characteristics of the various cephalometric

analyses, which enables the 'optimum' variables for the assessment of relationships, size and posture
of regions or structures to be selected. Following the presentation of some critical observations and
general concepts centering on the questions "Why do we choose a particular cephalometric analysis
over another?" and "Which is the best cephalometric evaluation method?", the author justifies his
selection of the 'best' variables for evaluating sagittal basal relationships, vertical basal relationships
and dento-alveolar relationships. Suggestions concerning the non-metric assessment of the skull and
surrounding anatomic units, and graphical representations of the numerical data and non-numerical
analyses arc also presented.
Chapter 4 comprises a step-by-step description of the most important methods for assessing
dentofacial changes using cephalometric supcrimpositions. The chapter also contains information
on superimpositions with regard to changes in the overall face, the maxilla and its dentition, the
mandible and its dentition, and the amount and direction of condylar growth as well as the evaluation
of mandibular roration.
7
Chapter 5 is an in-depth presentation and analysis of the errors of cephalometric measurements,
which can occur either during radiographic projection and measuring or during landmark
identification. The limitations of the various methods of growth prediction, and superimposition
techniques, are also discussed.
Chapter 6 is unique in the literature of the field. Starting with a comprehensive review of the most
important aspects of frontal cephalometry, it includes information on the technique, tracing and
identification of landmarks, and the aims of this diagnostic tool. A presentation of the most popular
and reliable frontal cephalometric analyses, variables and norms follows, accompanied by important
comments concerning their use.
Chapter 7 is the logical continuation of the preceding chapters, critically addressing some important
applications of cephalometric radiography, including the functions of analysis, assessment, comparison
and prediction.
Chapter 8 explains why cephalograms reveal valuable information that transcends their orthodontic
utility, and illustrates why cephalometric radiographs can provide diagnostic information concerning
abnormalities of the cranium, cervical spine, maxilla, paranasal sinuses and mandible.
Chapter 9 describes why and how cephalometrics has without doubt been the most frequently applied
quantitative technique within orthodontic research. It also discusses the various advantages and
limitations of cephalometry in research applications, and provides strict criteria and guidelines for
such applications.
Chapter 10 reviews the use of cephalometry to evaluate craniocervical angulation, pharyngeal

relationships, soft palate dimensions, and hyoid bone and tongue positions. The conditions for
obtaining proper cephalometric registrations are presented in detail, as well as the available
landmarks, variables, measurements and norms.
Chapter 11 introduces the specialized world of digital computed radiography, describing its scien
tific principles, technical aspects, cephalometric applications and future trends and developments.
Chapter 12 addresses the basic principles and benefits of using computerized cephalometry. It also
provides information concerning some of the systems currently on the market, and guidelines for
choosing the right one according to individual needs.
Chapter 13 comprises a collection of the most popular and well known numerical cephalometric
analyses. There is also an extensive reference list on other non-numerical analyses as well as
morphological and growth cephalometric data.
It is the hope of the editor that this collaborative effort will contribute to the better understanding
and use of cephalometric radiography, and that it will form a basis, reference source and stimulus
for further advances in orthodontics and related sciences.
Athanasios E Athanasiou
Thessaloniki
January 1995
s
CHAPTER 1
The Technique of Cephalometric Radiography

Smorntree Viteporn
INTRODUCTION technique for producing a lateral head film was

introduced by Pacini in 1922. With this method, the
A scientific approach to the scrutiny of human cran- size of the image was decreased by increasing the
iofacial patterns was first initiated by anthropolo focus-film distance to 2 m (78.7 in), but there was
gists and anatomists who recorded the various still some distortion because of head movement
dimensions of ancient dry skulls. The measurement during prolonged exposure time.
of the dry skull from osteological landmarks, called In 1931, Broadbent in the USA and Hofrath in
craniometry, was then applied to living subjects so Germany simultaneously presented a standardized
that a 'longitudinal growth study' could be under cephalometric technique using a high powered X-
taken. This technique - the measurement of the head ray machine and a head holder called a cephalostat
of a living subject from the bony landmarks located or cephalometer. According to Broadbent, the
by palpation or pressing through the supra-adjacent patient's head was centred in the cephalostat with
tissue - is called cephalometry. However, the the superior borders of the external auditory meatus
cephalometric method could never be wholly resting on the upper parts of the two ear-rods. The
accurate as long as measurements were taken lowest point on the inferior bony border or the left
through the skin and soft tissue coverage. orbit, indicated by the orbital marker, was at the
The discovery of X-rays by Roentgen in 1895 level of the upper parts of the ear-rods. The nose
revolutionized the dental profession. A radiograph- clamp was fixed at the root of the nose to support
ic head image could be measured in two dimensions, the upper part of the face (1.1,1,2). The focus-film
thereby making possible the accurate study of cran- distance was set at 5 feet (152.4 cm) and the
iofacial growth and development. The measurement subject-film distance could be measured to calcu
of the head from the shadows of bony and soft late image magnification. With the two X-ray tubes
tissue landmarks on the radiographic image became at right angles to each other in the same horizontal
known as roentgenographic cephalometry (Krog- plane, two images (lateral and posteroanterior)
man and Sassouni, 1957). A teleroentgenographic could be simultaneously produced.
I.I Broadbent cephalostat with head holder positioned with 1.2 Broadbent cephalostat with child's head adjusted inside the
cassette in place for a lateral cephalogram (after Broadbent, 1931; head holder (after Broadbent. 1931; reprinted with permission).
reprinted with permission).
Orthodontic Cephalometry
Then, in 1968, Bjork designed an X-ray cephalo- video tape (Skieller, 1967). M o r e recently, in 1988,
stat research unit with a built-in 5-inch image inten- a multiprojection cephalomctcr developed for
sifier that enabled the position of the patient's head research and hospital environments was introduced
to be monitored on a TV screen (1.3). The patient's by Solow and Kreiborg. This a p p a r a t u s ( 1 , 4 - 1 . 6 )
head position in the cephalostat was also highly featured improved control of head position and
reproducible. F u r t h e r m o r e , this unit allowed the digital exposure control as well as a number of tech
cephalometric X-ray examination of oral function nical operative innovations.
on the TV screen, which could also be recorded on
1.3 X-ray cephalo

stat unit w i t h built-
in 5-inch image in
tensifies The posi
t i o n of the head is
monitored on a T V
screen (after Bjork.
1968; reprinted
with permission).
1.4-1.6 These images show the cephalometric unit designed by

Solow and Kreiborg in 1988 f o r research and hospital environ
ments. 1.4 Lateral X-ray pillar w i t h X-ray tube, diaphragms. TV
camera, and laser-beam lenses (after Solow and Kreiborg. 1988;
1.5 Laser-beam
cross-projected on
t o t h e face ( a f t e r
S o l o w and K r e i
borg. 1988; reprint
ed with permission).
1.6 O p e r a t o r view of split-screen monitor showing lateral and

a n t e r i o r facial v i e w and r a d i o g r a p h i c image f o r c o n t r o l of
p o s i t i o n i n g (after S o l o w and K r e i b o r g . 1988; r e p r i n t e d with
permission).
in
The development of such special units, especially for TECHNICAL ASPECTS

roentgenocephalometric registrations of infants
(1.7,1.8), has significantly contributed to the study The basic components of the equipment for
of the growth and development of infants with producing a lateral cephalogram (Frommer, 1978;
craniofacial anomalies (Kreiborg et al, 1977). Barr and Stephens, 1980; Wuehrmann and Manson-
The lateral cephalometric radiograph (cephalo- Hing, 1981; Manson-Hing, 1985; Goaz and White,
gram) itself is the product of a two-dimensional 1987) are:
image of the skull in lateral view, enabling the rela • an X-ray apparatus;
tionship between teeth, bone, soft tissue, and empty • an image receptor system; and
space to be scrutinized both horizontally and ver • a cephalostat.
tically. It has influenced orthodontics in three major
areas:
• in morphological analysis, by evaluating the THE X-RAY APPARATUS
sagittal and vertical relationships of dentition, facial
skeleton, and soft tissue profile. The X-ray apparatus comprises an X-ray tube,
• in growth analysis, by taking two or more transformers, filters, collimators, and a coolant
cephalograms at different time intervals and system, all encased in the machine's housing. The X-
comparing the relative changes. ray tube is a high-vacuum tube that serves as a
• in treatment analysis, by evaluating alterations source of the X-rays. The three basic elements that
during and after therapy. generate the X-rays are a cathode, an anode, and the
electrical power supply (1.9).
1.7 and 1.8 These show the special unit designed for roentgen' 1.8 The X-ray tube above the cephalostat is tilted at 45° (after
cephalometric registrations of infants. 1.7 The position of the Kreiborg et al. 1977; reprinted with permission).
infant's head for the basal projection (after Kreiborg et al 1977;
II
The cathode is a tungsten filament surrounded by T h e a n o d e is stationary and comprises a small

a molybdenum focusing cup. T h e tungsten filament tungsten block embedded in a copper stem (the
serves as a source of electrons. It is connected to a target), which stops the accelerated electrons, whose
low-voltage circuit and a high-voltage circuit. A kinetic energy causes the creation of photons. Less
step-down transformer supplies the low-voltage than 1 % of the electron kinetic energy is converted
circuit with 10 V a n d a high current to heat the to X-ray photons; the rest is lost as heat. Although
filament until electrons are emitted. T h e production tungsten is a high atomic substance necessary for
of electrons, which form a cloud a r o u n d the producing X-ray photons, its thermal resistance is
filament, is called thermionic emission. A step-up unable to withstand the heat. Consequently, the
transformer supplies the high-voltage circuit to copper stem acts as a thermal conductor. This is an
create 6 5 - 9 0 kV. T h e differential potential between integral part of the coolant system, and it dissipates
the cathode and the a n o d e accelerates the electron the heat into the oil surrounding the X-ray tube.
cloud, which forms electron beams. T h e beams are The size of the focal spot, which determines
directed by the focusing cup to strike a small target image quality, follows the Benson line focus prin
on the anode called the focal spot. Bombardment of ciple (1.10). This principle says that the projection
this target by the electrons produces the X-ray beam. of the focal spot perpendicular to the electron beam.
STEP UP TPANShQRMER 1.9 X - r a y t u b e w i t h basic e l e m e n t s :

c a t h o d e , a n o d e , and e l e c t r i c a l p o w e r
supply.
mmuiLL
i TUNGSTEN FILAMENT TUNGSTEN TARGET*

CATHODE \ /
I FOCUSING CUP
£
U - ALUMINIUM DISK
STEP DOWN TRANSFORMFn
-i—r
7 f- LEAD DIAPHRAGM
1.10 Benson line focus principle showing

the effective focal spot created by a target
inclined at 20°.
CATHODE ANODE
ACTUAL FOCAL SPOT l I

I I
I I
EFFECTIVE FOCAL SPOT
*
12
The Technique ofCephalometrk Radiography
(the effective focal spot) is smaller than the actual QUALITY A N D QUANTITY OF X-RAYS
focal spot that projects perpendicular to the target.
Therefore, the target face in the X-ray tube is The X-ray is a form of electromagnetic radiation
oriented at an angle of 15-20° to the cathode, not that travels with a certain velocity and carries a
only to obtain a small focal spot, which will increase certain amount of energy. The energy is directly pro
image sharpness, but also to increase the heat portional to the wavelength. In general, X-rays have
capacity of the target. The siz.e or area of the effec extremely short wavelengths, enabling them to pen
tive focal spot created by the inclined target is etrate opaque substances and to be absorbed by
between I x 1 mm 2 and 1 x 2 mm 2 . them. The quality of the X-rays refers to their pen
The X-ray photons emerging from the target are etrative power, and is determined by the kilovoltage
made up of a divergent beam with different energy peak (kVp) applied across the cathode and the
levels. The Iow-energy (long-wavelength) photons anode. X-rays produced by the high kilovoltage
are filtered out by means of an aluminium filter. The peak are called hard X-rays - they have short wave
divergent X-ray beam then passes through a lead lengths and high penetrating power. X-rays
diaphragm (the collimator) that fits over the opening produced by the low kilovoltage peak are called soft
of the machine housing and determines the beam's X-rays - they have long wavelength and low pene
size and shape. Only X-rays with sufficient pene trating power.
trating power are allowed to reach the patient. The quantity of the X-rays is determined by the
The relationship between the intensity of the X- amount of bombarded electrons and is controlled
ray beam and the focus-film distance follows the by the tube current (measured in milliamperes) that
inverse square law, by which the intensity of the X- flows through the cathode filament and by the
rays is inversely proportional to the square of the duration of X-ray production or exposure time
focus-film distance (1.11). (measured in seconds).
THE IMAGE RECEPTOR SYSTEM
An image receptor system records the final product

of X-rays after they pass through the subject. The
extraoral projection, like the lateral cephalometrk
technique, requires a complex image receptor system
that consists of an extraoral film, intensifying
screens, a cassette, a grid, and a soft-tissue shield.
The extraoral film, which is either 8 inches X 10
inches (203 mm X 254 mm) or 10 inches x 12 inches
(254 mm x 305 mm), is a screen film that is sensi
tive to the fluorescent light radiated from the inten
sifying screen. Basic components of the X-ray film
are an emulsion of silver halide crystals suspended
in a gelatin framework and a transparent blue-tinted
cellulose acetate that serves as the base.
When the silver halide crystals are exposed to the
radiation, they are converted to metallic silver
deposited in the film, thereby producing a latent
image. This is converted into a visible and perma
I.I I Diagram illustrating the relation between the intensity of
nent image after film processing. The amount of
radiation and focus-film distance.
metallic silver deposited in the emulsion determines
13
film density, whereas the grain size of the silver THE CEPHALOSTAT
halide determines film sensitivity and definition.
Intensifying screens are used in pairs together The use of a cephalostat, also called a heac
with a screen film to reduce the patient's exposure or cephalometer, is based on the same prin
dose and increase image contrast by intensifying the that described by Broadbent (1931). The j
photographic effect of X-radiation. These intensi head is fixed by the two ear-rods that are i
fying screens consist of phosphorescent crystals, into the ear holes so that the upper border
such as calcium tungstate and barium lead sulphate, ear holes rest on the upper parts of the ear-rc
coated onto a plastic support. When the crystals are head, which is centered in the cephalo
exposed to the X-ray b e a m , they emit fluorescent oriented with the Frankfort plane paralle
light that can be recorded by the screen film. The floor and the midsagittal plane vertical and
brightness of the light is related to the intensity of to the cassette. The system can be moved v<
the X-rays and to the size and quality of the phos relative t o the X-ray t u b e , or t h e image r
phorescent crystal. system and the cephalostat as a whole can b<
Both the e x t r a o r a l film and the intensifying to a c c o m m o d a t e sitting or standing p
screens are packed inside a light-tight box called a Vertically adjustable chairs are also used. T
cassette; they must be placed in tight contact in dardized Frankfort plane is achieved by pla<
order to prevent the fluorescent light emitted by the infraorbital pointer at the patient's orbit a
intensifying screen radiating in all directions before adjusting the head vertically until the infra
reaching the film, as this would diminish the sharp pointer and the two ear-rods are at the san
ness of the image. T h e upper part of the face is supported
Of all the original or primary beams that emerge forehead clamp, positioned at the nasion.
from the X-ray apparatus, only 10% have adequate If it is necessary for the c e p h a l o g r a n
energy to penetrate tissue and p r o d u c e an accept produced in the natural head position, wh
able image on the film. T h e remaining 9 0 % are resents the true horizontal plane, the patieni
absorbed by the irradiated tissue and emitted as sec be standing u p and should look directly i
ondary or scatter radiation. Since secondary radia reflection of his or her own eyes in a mirror
tion travels obliquely to the primary beam and could ahead in the middle of the cephalostat (Sol
cause fogging of the image, a grid comprising alter Tallgren, 1971). In this case, the system h;
native radio-opaque and radiolucent strips is placed moved vertically. To record the natum
between the subject and the film to remove it before position, the ear-rods are not used for loci
it reaches the film. The radio-opaque strips of lead patient's head into a fixed position but serve
foil, which are angled toward the focal spot, act as the median sagittal plane of the patient at
the absorber, whereas the radiolucent strips of distance from the film plane, and to as;
plastic allow the primary beam to pass through the patient in keeping his or her head in a c
film. The absorption efficiency of the grid is deter position during e x p o s u r e . However, the e
mined by the grid ratio and the n u m b e r of radio- should allow for small adjustments of the
o p a q u e strips. The grid ratio is the ratio of the correct undesirable lateral tilt or rotation
height or thickness of the radiopaque strips to the and Kreiborg, 1988).
width of the radiolucent slots. The projection is taken w h e n the teeth
The soft-tissue shield is an aluminium wedge that centric occlusion and the lips in repose, unle
is placed over the cassette or at the w i n d o w of the specifications have been recommended (e.g. ^
X-ray apparatus in order to act as a filter and reduce mouth open or with a specific interocclus;
overpenetration of the X-rays into the soft-tissue tration used as orientation). The focus-film <
profile. The thin edge of the shield is positioned pos is usually 5 feet (152.4 cm), but different di
teriorly over the bony area, while the thick edge is have been also reported. It is usual for the 1
positioned anteriorly over the soft-tissue area. of the head to face the cassette.
isexf
QUALITY O F T H E R A D I O G R A P H I C
CEPHALOMETRIC I M A G E
Image quality is a major factor influencing the The processing procedure

accuracy of cephalometric analysis (Franklin 1952, Film processing consists of developing, rinsing,
Krogman and Sassouni, 1957; Frommer, 1978; Barr washing, drying, and mounting the exposed film. An
and Stephens, 1980; Wuehrmann and Manson^ invisible image, produced when the silver halide
Hing, 1981; Goaz and White, 1987). An acceptable crystals are exposed to the X-rays, is altered to a
diagnostic radiograph is considered in the light of visible and permanent image on the film by chemical
two groups of characteristics: solutions. The image density is directly proportion
• visual characteristics; and al to temperature of the developing solution and
• geometric characteristics. developing time.
The size of the silver halide crystals in the film
emulsion determines the film speed. A film with
VISUAL CHARACTERISTICS large grain size (high-speed film) produces greater
density than a film with small grain size.
The visual characteristics - density and contrast -
are those that relate to the ability of the image to Contrast
demonstrate optimum detail within anatomical Contrast is the difference in densities between
structures and to differentiate between them by adjacent areas on the radiographic image. Factors
means of relative transparency. controlling the radiographic contrast are:
• tube voltage - the kilovoltage peak has the most
Density effect on radiographic contrast. When the kilo
Density is the degree of blackness of the image when voltage peak is low, the contrast of the film is
it is viewed in front of an illuminator or view box. high, and the film has short-scale contrast. On the
The radiographic density is calculated from the other hand, if the kilovoltage peak is high, the
common logarithm of the ratio of the intensity of contrast of the film is low, and the film has long-
the light beam of the illuminator striking the image scale contrast.
(Io) to the intensity of the light transmitted through • secondary radiation or scatter radiation - the sec
the film (It): ondary radiation caused by low energy X-ray
Density = log Io/lt beams decreases the contrast by producing film
fog. The amount of secondary radiation is
As the X-ray image is formed as a result of pro directly proportional to the cross-sectional area,
cessing in which the silver halide crystals in the thickness and density of the exposed tissues as
emulsion of the film being exposed to the X-rays are well as the kilovoltage peak. Several devices have
converted to metallic silver, the two main factors been incorporated into the cephalometric system
that control the radiographic density are: to remove secondary radiation, including an alu
• the exposure technique; and minium filter, lead diaphragm and grid.
• the processing procedure. • subject contrast - this refers to the nature and
properties of the subject, such as thickness,
Exposure technique density, and atomic number.
The exposure factors related to image density are: • processing procedure - the temperature of the
• tube voltage (kilovoltage peak, kVp) developing solution affects image contrast. The
• tube current (milliamperage, mA) higher the temperature the greater the contrast.
• exposure time (second, S)
• and focus-film distance (D). Density and contrast are the image characteristics
The relationship of image density and these factors that are usually affected when the kilovoltage peak
is expressed as an equation: is altered. However, only the radiographic density
Density = (kVp x mA x S)/D can be altered without changing the contrast when
the kilovoltage peak is constant and the mil-
liamperage-second is altered.
15
Orthodontic Cephalomvtry
GEOMETRIC CHARACTERISTICS rays emitted from the focal spot are actually pro
ducing a shadow of the object (the umbra) (1.12).
The geometric characteristics are:
• image unsharpncss; Image unsharpness
• image magnification; and Image unsharpness is classified into three types
• shape distortion. according to aetiology, namely: geometric, motion
and material.
These three characteristics are usually present in Geometric unsharpness is the fuzzy outline in a
every radiographic image, owing to the nature of the radiographic image caused by the penumbra.
X-ray beam and its source. Factors that influence the geometric unsharpness are
X-rays, by their nature, are divergent beams size of the focal spot, focus-film distance, and
radiated in all directions. Consequently, when they object-film distance. In order to decrease the size of
penetrate through a three-dimensional object such the penumbra, the focal spot size and the
as a skull, there is always some unsharpness and object-film distance should be decreased and the
magnification of the image, and some distortion of focus-film distance increased (1.13). Geometric
the shape of the object being imaged. unsharpness is defined by the following equation:
The focal spot from which the X-rays originate,
although small, has a finite area, and every point on Geometric unsharpness = (focal spot size x
this area acts as an individual focal spot for the orig object-film distance)/focus-film distance
ination of X-ray photons. Therefore, most of the X-
FOCAL SPOT FOCAl SPOT ANODE
FOCAL SPOT ANODE
OBJECT
OBJECT
FUN
Fll«
PENUMBRAS
III
OBJECT
AN0D£
FOCAL SPOT ANODE FOCAL SPOT X \
PENUMBRA PENUMBRA
FILM 3
UMBRA"
1.12 Radiographic image produced by a divergent beam

originating from a definite focal spot.
OBJtCT
OHJfctI
FILM
FILM C
PENUMBRAS PENUMBRAS
ID)
1.13 These diagrams illustrate the factors influencing the size of

the penumbra (A). Penumbra size decreases if the focal spot size
decreases (B). the focus-film distance increases (C), or the focus-
film distance is increased while object-film distance is decreased (D).
16
Motion unsharpness is caused by movement of the FACTORS AFFECTING THE QUALITY OF

patient's head and movement of the tube and film. THE IMAGE
Material unsharpness is related to two factors.
First, it is directly proportional to the grain size of Quality of the image is controlled by the manufac
the silver halide crystals in the emulsion. Secondly, turer of the X-ray equipment and by the operator.
it is related to the intensifying screens, which, In general, the manufacturer provides pre-pro
although they can minimize X-ray dose to the grammed exposure factors consisting of mil-
patient, also result in unsharpness that is related ro liamperage (mA), kilovoltage peak (kVp) and
the size of the phosphorescent crystals, the thickness exposure time (S), which enable image density and
of the fluorescent layer, and the film-screen contact. contrast to be controlled when object density and
If the intensifying screens are not in tight contact thickness are varied. The variations in the exposure
with the film, fluorescent light emerges from the factors depend on the type of X-ray machine,
screen in all directions, thus adding to the image dis target-film distance, the film-screen combination
tortion. and the grid chosen (Table 1.1). Usually the mil-
liamperage setting does not exceed 10 mA, the kilo-
Image magnification voltage is about 60-90 kV, and the exposure time is
Image magnification is the enlargement of the actual not longer than 3 seconds. The grid ratio is 5:1, with
size of the object. Factors influencing image mag 34 lines per centimetre.
nification are the same factors as those that influ The operator can adjust these exposure factors
ence geometric unsharpness (i.e. the grain size of the when subject density as well as thickness are altered,
silver halide crystals in the emulsion, and various in order to maintain the overall image density of dif
features of the intensifying screens). The percentage ferent radiographs. The exposure time is the com
of magnification can be calculated by the equation: monest factor to change, since altering it has the
greatest effect, especially on image density. Altering
. , .0 (focus'tilm distance) the milliamperage alone is not recommended, since
Magnih- = < > -IxlOO
canon (%) (focus-film distance) - (object-film distance^ the 0-15 mA range on dental X-ray machines is too
small to be varied and the differences in image
So, for example, if the focus-film distance is 190 cm density that can be achieved by altering the mil
(74.8 inches) and the object-film distance is 10 cm liamperage alone are almost undetectable. Altering
(3.9 inches), the percentage of magnification of mid- the kilovoltage peak affects not only image contrast
sagittal structures in the lateral cephalogram will be but also exposure time, since increased kilovoltage
5.5%. increases the number of photons as well as the
amount of secondary radiation. In order to reduce
Shape distortion secondary radiation, exposure time has to be
Shape distortion results in an image that does not reduced. An increase of 15 kV necessitates a halving
correspond proportionally to the subject. In the case of the exposure time (Wuehrmann and Manson-
of a skull, which is a three-dimensional object, the Hing, 1981). Therefore, in order to maintain image
distortion usually occurs as a result of improper ori density and contrast of subjects with different thick
entation of the patient s head in the cephalostat or ness and density, the milliamperage and kilovoltage
improper alignment of the film and central ray. This have to correspond with the type of film and inten
kind of distortion can be minimized by placing the sifying screens recommended by the manufacturer.
film parallel to the midsagittal plane of the head and Image density and contrast can also be affected
projecting the central ray perpendicularly to the film by film processing. When using an automatic film
and the midsagittal plane. The lateral cephalogram processor, density and contrast are both controlled
is further distorted by the foreshortening of dis by the temperature of the developer and by the
tances hetween points lying in different planes and developing time.
by the radial displacement of all points and struc The optimum temperature of the developer and
tures that are not located on the central ray. developing time are 68°F and 5 minutes respectively.
17
Orthodontic Cephalametry
Equipment I: Veraview md-Cp (J Morita Corporation) - Model X-102 md-Cp

Tube voltage 60-80 kV (5-stage. push-button system)
Tube current 5-10 mA (6-stage, push-button system)
Exposure time 0.5-3.0 sec (7-stage, push-button system)
Focal spot size 0.5 mm x 0.5 mm
Target film distance 150 cm
Filtration 2.1 mm Aluminium Filtration Equivalent
X-ray 34 lines per cm or 5:1
Standard exposure
kV mA Sec
Patient under 15 years
Female 70 8 1.7
Male 70 8 1.7
Patient over 16 years
Female 70 7 2.2
Male 75 9 2.2
Equipment 2: Orthoralix SD Ceph (Phillips Electrical Corporation)

Tube voltage 60-80 kV in steps of 2 kV
Tube current 4-14 mA in steps of I m A
Exposure time 016-2.5 sec
X-ray grid 34 lines per cm or 5:1
Standard exposure automatic dosage control

kV mA Sec
Patient
Child 68 10 0.8
Small patient 72 10
Medium patient 76 10
Large patient 80 10
Equipment 3: Orthophos C D (Siemens Corporation)

Tube voltage 60-90 kV (in 11 steps)
Tube current 4-14 mA
Exposure time 0.01-4 sec
X-ray grid (not mentioned by manufacturer)
Standard exposure automatic dosage control

kV mA Sec
Patient
Child 73 15 0.4
Small patient 73 15 0.5
Medium patient 77 14 064
Large patient 84 13 0.8
Table I . I Examples of cephalometric equipment w i t h standard exposure.
IS
The developing time is controlled by the speed of the PROTECTION FROM RADIATION
roller, and the operator can lower the speed or the
roller if a darker image is required o r increase the X-rays are a form of electromagnetic radiation that
speed to produce a lighter image. However, properly can cause biological changes to a living organism by
exposed films d o not visibly increase in density even ionizing the atoms in the tissue they irradiate. After
if the developing time is increased by as much as collision, the X-ray p h o t o n loses all or part of its
50%. Excessive developing rime also increases film energy to an orbital electron, thereby dislodging the
fogfWuehrmann and M a n s o n - N i n g , 1981). electron from its orbit and forming an ion pair. If
Image sharpness and magnification are controlled the X-ray photon is low-energy radiation, all of its
by the manufacturer and the operator. T h e m a n u energy will be given off to the orbital electron,
facturer provides the most efficient focal spot size, which causes this electron to break away from the
target-film distance, collimation, a n d filtration a t o m it is orbiring. T h e resultant electron, called a
measures so that the m a x i m u m X-ray beams with photoelecrron, has sufficient energy to strike other
the best size and shape are p r o d u c e d . In modern orbital electrons, which is done until its own energy
cephalometric equipment, the area of the effective is expended. This process is called the photoelectric
focal spot size is less than 1 x I mm 2 , the target-film effect. O n the o t h e r h a n d , if the X-ray p h o t o n is
distance is 152.4 cm (5 feet)^ the shape of the X-ray medium-energy radiation, part of its energy will be
beam is controlled by a rectangular diaphragm, the given off to the orbital electron to produce a recoil
filtration of which is not less than 2 m m . Aluminium electron ( C o m p t o n electron), and the X-ray photon
Filtration Equivalent is a unit of filtration. is left in a weakened condition. A Compton electron
In order to facilitate correct positioning of the breaks away from the atom in the same manner as
patient's head, modern cephalometers provide laser a photoelecrron. This process is, not surprisingly,
beams that indicate the true vertical and horizon called the Compton effect. The photoelectric effect
tal planes (1.5). The vertical beam projects into the and the C o m p t o n effect both p r o d u c e many ion
midplane of the head holder, and the horizontal pairs, which relate directly to the a m o u n t of tissue
beam projects t h r o u g h t h e ear-rods (Solow a n d decomposition. Although the a m o u n t of radiation
Kreiborg, 1988). The operator plays a major role in used in clinical diagnosis is very small, protective
controlling the patient's head position, the measures are obligatory for both patient and
object-film distance and the movement of the X-ray o p e r a t o r (Goaz and White, 1987; M a n s o n - H i n g ,
tube. In cephalometric systems with vertical 1985).
movement of the X-ray rube, the cephalostat and the
image receptor are synchronized by the same switch Protective measures that aim t o minimize the
so that the X-ray beam strikes the upper parr of the exposure t o the patient include:
ear-rod. The operator must adjust the patient's head • Utilization of a high speed film and intensifying
so that the external auditory meatuses rest on the screens in order t o reduce the dose of radiation
upper part of the two ear-rods, the Frankfort plane and exposure time.
is horizontal, and the centre line of the face is • Filtration of secondary radiation or scatter radi
vertical (1.2). If the X-ray image is taken with the ation produced by low energy X-ray photons by
patient's head in its natural position, the patient is an aluminium filter.
asked to assume a conventional position while • COIIimation by a d i a p h r a g m m a d e of lead in
looking directly into a mirror, as described earlier. order to achieve the optimum beam size.
In cephalometric units that provide a light source to • Proper exposure technique and processing to
facilitate the transverse adjustment of the patient's avoid unnecessary repetition of the procedure.
head, the operator must adjust t h e patient's head • The patient's w e a r i n g a lead a p r o n in o r d e r t o
until the vertical beam passes the midline of the face absorb scatter radiation.
and the horizontal beam passes through the ear-rods
(Solow and Kreiborg, 1988). When the same patient In order t o avoid scatter radiation, the o p e r a t o r
is to be radiographed again in the future, it is rec should stand at least 6 feet (182.9 cm) behind the
ommended that the milliamperage, kilovoltage peak tube head, or should stand behind a lead protective
and exposure time be noted on the patient's chart. barrier while making the X-ray exposure.
19
REFERENCES
Barr J H , Stephens RG (1980) Dental Radiology. Krogman WM, Sassouni V (1957) A Syllabus of
(WB Saunders: Philadelphia.) Roentgenographic Cephalometry. (University of
Pennsylvania: Philadelphia,)
Bjork A (1968) The use of metallic implants in the
study of facial growth in children: method and Manson-Hing LR (1985) fundamentals of Dental
application. Am J Phys Anthropol 29:243-54. Radiography. (Lea and Febiger: Philadelphia.)
Broadbent BH (1931) A new X-ray technique and Pacini AJ (1922) Roentgen ray anthropometry of
its application to orthodontia. Angle Orthod the skull. J Radiol 3:230-8.
1:45-60.
Skieller V (1967) Cephalometric growth analysis in
Franklin JB (1952) Certain factors of aberration to treatment of overbite. Trans fur Orthod Soc:
be considered in clinical roentgenographic 147-57.
cephalometry. Am J Orthod 38:351-68.
Solow B, Kreiborg S (1988) A cephalometric unit
Frommer H H (1978) Radiology for Dental for research and hospital environments. Eur J
Auxiliaries. (CV Mosby: St Louis.) Orthod 10:346-52.
Goaz PW, White SC (1987) Oral Radiology: Solow B, Tallgren A (1971) Natural head position
Principles and Interpretation. (CV Mosby: St Louis.) in standing subjects. Acta Odontol Scand
29:591-607.
Hofrath H (1931) Die Bedeutung der Roentgenfern
und Abstandsaufnahrne fur die Diagnostik der Wuehrmann AH, Manson-Hing LR (1981) Dental
Kieferanomalien. Fortschr Orthodont 1:232-48. Radiology. (CV Mosby: St Louis.)
Kreiborg S, Dahl E, Prydso U (1977) A unit for

infant roentgencephalometry. Dentomaxillofac
Radiol 6:107-11.
20
CHAPTER 2
Anatomy, Radiographic Anatomy and Cephalometric

Landmarks of Craniofacial Skeleton, Soft Tissue Profile,
Dentition, Pharynx and Cervical Vertebrae
Smorntree Viteporn and Athanasios E Athanasiou
INTRODUCTION process joins with the frontal process of the zygo

matic bone forming the lateral border of the orbit.
A lateral cephalogram is one of the orthodontic The frontal sinus (12) lies in the frontal bone, in an
records that provides information about the sagittal area superior to the articulation with the nasal bone.
and vertical relations of:
• the craniofacial skeleton; Radiographic a n a t o m y (2.2, p.22)
• the soft tissue profile; Starting from the upper anterior part of the skull
• the dentition; at the coronal suture (1), the frontal bone appears
• the pharynx; and as two radio-opaque lines that descend parallel to
• the cervical vertebrae. each other. The outer radio-opaque line represents
the external cortical plate of the frontal bone (2),
These structures and their relationships to each and the inner line represents the internal cortical
other are scrutinized by means of linear and angular plate (3), which forms the anterior border of the
measurements as well as by the use of ratios based anterior cranial fossa. These two parallel lines
on the various cephalometric landmarks. These diverge at the forehead area where the frontal sinus
cephalometric landmarks should be identified; (4) appears as a radiolucent area between them. The
errors in their identification can be minimized by a external cortical plate terminates at the anterior part
thorough knowledge of the anatomy of the skull of the frontonasal suture (5), which appears as a
and by an awareness of the close correspondence radiolucent line between the frontal and the nasal
between gross anatomy and radiographic appear bones (6). The internal cortical plate extends hori
ance of each structure and the detailed criteria for zontally and posteriorly, thus terminating at the
identification of each anatomical cephalometric small radio-opaque triangular area that represents
point. the frontosphenoethmoidal suture (7),
Above the horizontal part of the internal cortical
plate there are two radio-opaque lines. The upper
CRANIOFACIAL SKELETON most of these two lines, which appears as a wavy
radio-opaque line, represents the endocranial
surface of the frontal bone (8), which forms the
FRONTAL BONE floor of the anterior cranial fossa. The harmonious
radio-opaque curve below the wavy line represents
Anatomy (2.1, p.22) the exocranial surface of the frontal bone (9), which
The frontal hone (1) forms the anterior part of the forms the roof of the orbit. This line extends pos
cranial vault. It joins posteriorly with the parietal teriorly to the lesser wings of the sphenoid bone (10)
bones (2) at the coronal suture (3). It joins inferi- and to the anterior clinoid (11). Anteriorly, it starts
orly with the sphenoid bone (4) and the ethmoid at the area of the frontal sinus where the junction of
bone (5) at the frontosphenoethmoidal suture. the roof of the orbit and its lateral border can be
Anteriorly, it joins with the nasal bones (6), with the identified as an angular radio-opaque shadow. The
maxilla (7), and the zygoma tic bone (8) at the fron- lateral border of the orbit appears as a curved radio-
tonasal suture (9), the frontomaxillary suture (10), opaque line, which represents the anterior margin
and the frontozygomatic suture (11), respectively. of the zygomatic process of the frontal bone (12).
The lower anterior part of the frontal bone forms At the same area, the posterior margin of the zygo
the roof of the orbit, and laterally its zygomatic matic process of the frontal bone (13) can be iden-
21
2.1 Photograph of the lateral aspect (A) and the medial aspect 6 nasal bone
(B) o f the frontal bone. 7 maxilla
1 frontal bone 8 zygomatic bone
2 parietal bone 9 frontonasal suture
3 coronal suture 0 frontomaxillary suture
4 sphenoid bone 1 frontozygomatic suture
5 ethmoid bone 2 frontal sinus
2.2 Radiograph of the lateral view of the frontal bone. 8 endocranial surface of frontal bone
1 coronal suture 9 exocranial surface of frontal bone
2 external cortical plate of frontal bone 10 lesser wing oi sphenoid bone
3 internal cortical plate of frontal bone 11 anterior clinoid
4 frontal sinus 12 anterior margin of zygomatic process of frontal bone
5 frontonasal suture 13 posterior margin of zygomatic process of frontal bone
6 nasal bone 14 anterior margin of frontal process of zygomatic bone
7 frontosphenoethmoidal suture 15 posterior margin of frontal process of zygomatic bone
22
Anatomy, Radiographic Anatomy and Ccphalometric Landmarks
2.3 Cephalometric landmarks related to the

frontal bone.
tified as a radio-opaque line descending parallel articulates with the frontal and nasal bones (uni
behind the lateral border of the orbit. These two lateral); FMN is on the anterior cranial base,
lines merge with the radio-opaque lines of the unlike Na, and can therefore also be used for
anterior and posterior margins of the frontal process measuring or defining the cranial base (Moyers,
ofthezygomatic bone (14, 15). 1988);
Na - nasion - the most anterior point of the fron-
Cephalometric landmarks (2.3) tonasal suture in the median plane (unilateral);
• F-point F (constructed) - this point approxi SE - sphenoethmoidal - the intersection of the
mates the foramen caecum and represents the shadows of the greater wing of the sphenoid and
anatomic anterior limit of the cranial base, con the cranial floor as seen in the lateral cephalo-
structed as the point of intersection of a line per gram;
pendicular to the S-N plane from the point of SOr - supraorbitale - the most anterior point of
crossing of the images of the orbital roofs and the the intersection of the shadow of the roof of the
internal plate of the frontal bone (Coben); orbit and its lateral contour (bilateral) (Sassouni);
• FMN - frontomaxillary nasal suture - the most RO - roof of orbit - this marks the uppermost
superior point of the suture, where the maxilla point on the roof of the orbit (bilateral) (Sassouni).
23
PARIETAL BONES
Anatomy (2.4) Radiographic anatomy (2.5)

The parietal bones (1) are a pair of quadrangular Starting from the upper part of the skull at the
cup-shaped bones. They articulate with each other coronal suture (3), each parietal bone (1) appears as
at the sagittal suture, which is situated at the midline two radio-opaque lines that curve parallel to each
area of the top of the cranium. They join anterior other and terminate at the lambdoid suture (5). The
ly with the frontal hone (2) at the coronal suture (3), lambdoid suture can be identified as an oblique radi-
posteriorly with the occipital bone (4) at the olucent line between the parietal and the occipital
lambdoid suture (5), and inferiorly with the bones (4). Inferiorly, the parietal bone is connected
temporal bone (6) and the greater wings of the with the temporal bone (6) and the greater wing of
sphenoid bone (7). the sphenoid bone (7).
2.4 Photograph of the parietal bone.

1 parietal bone
2 frontal bone
3 coronal suture
4 occipital bone
5 lambdoid suture
6 temporal bone
7 greater wing of sphenoid bone
2.5 Radiograph of the parietal bone.

1 parietal bone
2 frontal bone
3 coronal suture
4 occipital bone
5 lambdoid suture
6 temporal bone
7 greater wing of sphenoid bone
24
Anatomy, Radiographic Anatomy and Cephalometric landmarks
OCCIPITAL B O N E plate (5). The two radio-opaque lines join together

at the posterior border of the foramen magnum
Anatomy (2.6) where the opisthion point (6) is identified.
The occipital bone can be divided into three Anterior to the squamous portion of the occipi
portions: tal bone is the occipital condyle (7), which appears
• the squamous portion (1); as a curved radio-opaque line. Its anterior part
• the occipital condyle (2); and passes the superior limit of the odontoid process of
• the basioccipital (3). the axis (8), identified as a triangular radio-opaque
area. The occipital condyle turns into the basioc
The squamous portion forms the most posterior cipital (9) at the point where a small radiolucent
part of the cranial vault. Its external surface includes triangle with its apex facing downward can be iden
the most prominent part, called the external occip tified. The basioccipital appears as a triangular
ital protuberance (4). The internal surface can be radio-opaque area whose apex joins with the occip
divided into superior and inferior fossae by the ital condyle and whose base articulates with the pos
transverse groove. At the middle of these fossae terior surface of the sphenoid bone (10) at the
there is the internal protuberance (5) corresponding spheno-occipital synchondrosis.
with the external occipital protuberance. The occip The other two sides of the triangle are the
ital condyles flank the opening for the spinal cord endocranial and the exocranial surfaces of the occip
and form the foramen magnum (6). The basioccip ital bone (11, 12), each of them having double
ital articulates with the sphenoid bone (7) at the cortical plates identified as two radio-opaque lines.
spheno-occipital synchondrosis. The point where the endocranial and the exocranial
surfaces converge is identified as the basion point
Radiographic anatomy (2.7, p.26) (13), which represents the most posteroinferior
Starting from the lambdoid suture (1), which point of the basioccipital and also the most anterior
appears as a radiolucent line between the occipital point of the foramen magnum. The basion point
bone (2) and the parietal bones (3), the squamous usually lies 2-3 mm posterior to the point where the
portion of the occipital bone appears as two radio- radio-opaque line of the exocranial surface turns
opaque lines that descend parallel to each other. The into the anterior surface of the occipital condyle.
outer radio-opaque line represents the external Alternatively, it can be though of as being 4-6 mm
cortical plate of the occipital bone (4) and the inner superior to the superior limit of the odontoid
radio-opaque line represents the internal cortical process of the axis.
2.6 Photograph of the lateral aspect (A) and the medial aspect 4 external occipital protuberance
(B) of the occipital bone. 5 internal protuberance
1 squamous portion of occipital bone 6 foramen magnum
2 occipital condyle 7 sphenoid bone
3 basioccipital
25
Cephalometric landmarks (2.8) Bo - Bolron point - the highest point in the

• Ba - basion - the median point of the anterior upward curvature of the retrocondylar fossa (uni
margin of the foramen magnum can he located lateral) (Broadbent);
by following the image of the slope of the inferior O p - opisthion - the posterior edge of foramen
border of the basilar part of the occipital bone to magnum (unilateral).
its posterior limit (unilateral) (Coben);
2.7 Radiograph of the lateral view of the occipital bone. 7 occipital condyle
1 lambdoid suture 8 superior limit of o d o n t o i d process of the axis
2 occipital bone 9 basioccipital
3 parietal bone 10 sphenoid bone
4 external cortical plate of occipital bone 11 endocranial surface of occipital bone
5 internal cortical plate of occipital bone 12 exocranial surface of occipital bone
6 opisthion point 13 basion point
2.8 Cephalometric landmarks related to

the occipital bone.
26
Anatomy, Radiographic Anatomy and Cephalometric Landmarks
SPHENOID BONE The pterygomaxillary fissure appears as a radi-

olucent inverted teardrop surrounded anteriorly by
Anatomy (2.9, p.28) the radio-opaque line of the maxillary tubcrosity (4)
Anteriorly, the sphenoid bone articulates with the and posteriorly by the radio-opaque line of the
maxilla (1) and the palatine bone (2); anterosupe- anterior surface of the pterygoid process of the
riorly it articulates with the ethmoid bone (3) and sphenoid bone (5), which continues from the vertical
the frontal bone (4) at the fronrosphenoethmoidal radio-opaque line of the anterior border of the
surure. It consists of the body and the three paired sphenoid body (2).
processes - the lesser wings (5), the greater wings (6) At the roof of the fissure (3) are two radiolucent
and the pterygoid process (7). areas - the foramen rotundum and the sphenopala
The sphenoid body is occupied by the two air- tine foramen. The foramen rotundum (6) lies at the
filled cavities called the sphenoid sinus (8). Its superoposterior point of the fissure. The
superior surface has a deep depression of a saddle sphenopalatine foramen (7) is a helpful reference
like appearance called the sella turcica (9), which area for identifying the roof of the pterygomaxillary
houses the pituitary gland. The anterior limit of the fissure, since it usually lies right above the tail of the
sella turcica is the anterior clinoid (10), the poste middle nasal concha (8). The middle nasal concha
rior limit is the posterior clinoid (11) and the appears as a light radio-opaque projection in front
dorsum sellae (12). of the pterygomaxillary fissure.
The lesser wings of the sphenoid (5) project ante The planum sphenoidale, or the superior surface
riorly to the sella turcica (9), where the optic canals of the sphenoid body (9) is represented by the hor
(13) can be seen. The superior surfaces of the lesser izontal line that continues posteriorly from the two
wings form the floor of the anterior cranial fossa radio-opaque lines of the internal cortical plate of
and their inferior surfaces form the most posterior the frontal bone and the cribriform plate of the
parr of the orbital roof. ethmoid bone. The posterior limit of the planum
The greater wings (6) project from the postero- sphenoidale is the optic groove (10), which contains
lateral portion of the body. They articulate lateral the optic chiasma. The optic groove terminates at
ly with the frontal (4) and parietal (14) bones, and the tuberculum sellae (11), which is the anterior
posteriorly with the squamous portion of the tem limit of the sella turcica (13). Above this area is a
poral bone. radio-opaque line representing the anterior clinoid
The pterygoid processes (7) project inferiorly process of the lesser wing of the sphenoid bone (12).
from the root of the greater wings (6). Each process The shadow of the sella turcica (13) has an ellip
consists of two plates, the medial and the lateral tical shape. The most medial radio-opaque line in
pterygoid plates (15,16), which are separated by the the median plane represents the medial surface of
deep fossa. The inferior end of the medial pterygoid the sella and the most inferior radio-opaque line rep
plate is a thin curved process called the pterygoid resents the floor of the sella. The posterior limit of
hamulus (17). the sella is the posterior clinoid (14) and dorsum
Between the posterior border of the maxilla (1) sellae (15), which is identified as a radio-opaque line
and the anterior surface of the pterygoid process (7) that extends downwards and backwards to the
is the pterygomaxillary fissure (18), with an inverted sphcno-occipital synchondrosis.
teardrop shape. The sphenopalatine foramen (19) is At the centre of the sphenoid body is the radi
situated at the roof of the pterygomaxillary fissure olucent area representing the sphenoid sinus (16).
(18). Inferior to the sinus is the endocranial surface of the
greater wing of the sphenoid bone (17), identified
Radiographic anatomy (2.10, p.28) as a radio-opaque curve. Its anterior part curves
Starting from the small radio-opaque triangular area upwards and crosses the vertical radio-opaque line
of the frontosphenoethmoidal suture (I), there are representing the anterior border of the sphenoid
two radio-opaque lines, one vertical and the other body. Its posterior part merges with the squamous
horizontal. The vertical line represents the anterior portion of the temporal bone to form the roof of the
border of the sphenoid body (2), and it terminates glenoid fossa.
at the centre of the pterygomaxillary fissure (3).
27
2.9 Photograph of the lateral aspect (A) and the medial 10 anterior clinoid
aspect (B) of the sphenoid bone. 11 posterior clinoid
1 maxilla 12 dorsum sellae
2 palatine bone 13 optic canal
3 ethmoid bone 14 parietal bone
4 frontal bone 15 medial pterygoid plate
5 lesser wing of sphenoid bone 16 lateral pterygoid plate
6 greater wing of sphenoid bone 17 pterygoid hamulus
7 pterygoid process of sphenoid bone , 18 pterygomaxillary fissure
8 sphenoid sinus 19 sphenopalatine foramen
9 sella turcica
2.10 Radiograph of the lateral view of the sphenoid 9 planum sphenoidale

bone. 0 optic groove
1 frontosphenoethmoidal suture 1 tuberculum sellae
2 anterior b o r d e r o f sphenoid body 2 anterior clinoid
3 pterygomaxillary fissure 3 sella turcica
4 maxillary tuberosity 4 posterior clinoid
5 anterior surface of pterygoid process 5 dorsum sellae
6 foramen rotundum 6 sphenoid sinus
7 sphenopalatine foramen 7 greater wing of sphenoid bone
8 middle nasal concha
28
2.1 I Cephalometric landmarks related t o

the sphenoid bone.
Cephalometric landmarks (2.11) TEMPORAL BONES

• Cl-clinoidale - the most superior point on the
contour of the anterior clinoid (unilateral); A n a t o m y (2.12, p.30)
• Ptm - pterygoniaxillary fissure - a bilateral Kach temporal bone consists of two portions:
teardrop-shaped area of radiolucency, the • the squamous portion; and
anterior shadow of which represents the poste • the petrous portion.
rior surfaces of the tuberosities of the maxilla; the
landmark is taken where the two edges, front and The squamous portion (1) is a large flat bone
back, appear to merge inferiorly; forming the lateral wall of the cranium. Its superior
• S - sella - this is the point representing the surface articulates with the parietal bone (2) at the
midpoint of the pituitary fossa (sella turcica); it squamoparietal suture (3). Its inferior surface has an
is a constructed point in the median plane; oval depression called the glenoid fossa (4) to which
• Sc-midpoint of the entrance to the sella - this the mandibular condyle (5) articulates. Anterior to
point represents the midpoint of the line con the fossa is the articular tubercle (6); posterior to the
necting the posterior clinoid process and the fossa is the postglenoid process (7); and superior to
anterior opening of the sella turcica; it is at the the fossa is a finger-like projection - the zygoma tic
same level as the jugum sphenoidale and it is process of the temporal bone (8) - which articulates
independent of the depth of the sella (Schwarz); anteriorly with the zygomatic bone (9) at the zygo-
• SE- sphenocthmoidal - the intersection of the maticotemporal suture (10).
shadows of the great wing of the sphenoid and the The petrous portion is an irregular bone forming
cranial floor as seen in the lateral cephalogram; the inferior part of the temporal bone. Its external
• Si - floor of sella - the lowermost point on the surface houses an oval-shaped opening - the
internal contour of the sella turcica (unilateral); external auditory meatus (11). The external
• Sp-dorsum sella - t h e most posterior point on the auditory meatus communicates with the other
internal contour of the sella turcica (unilateral). round-shaped opening, the internal auditory meatus
(12). Posterior to the external auditory meatus is a
29
Orthodontic Cepbalometry
prominent round, rough part called the mastoid apex pointing upwards and backwards. The side o
process (13). This process is occupied by the air the triangle that appears as the anterosuperior radio
spaces called the mastoid air cells. Inferior and opaque line represents the posteroinferior limit o:
medial to the external auditory meatus is a pointed the middle cranial fossa (1). This radio-opaque lint
bony projection called the styloid process (14). continues anteriorly to the endocranial surfaces oi
the squamous portion of the temporal bone and tht
Radiographic anatomy (2.13) greater wing of the sphenoid bone. The other side
The major part of the temporal bone that can of the triangle, which appears as a vertical line, rep
usually be identified from the lateral cephalogram resents the anterior limit of the posterior crania
is the endocranial surface of the petrous portion. It fossa (2).
appears as a triangular radio-opaque area with its
2.12 Photograph of the lateral aspect (A) and medial aspect 7 postglenoid process
(B) of the temporal bone. 8 zygomatic process of temporal bone
1 squamous portion of temporal bone 9 zygomatic bone
2 parietal bone 10 zygomaticotemporal suture
3 squamoparietal suture 11 external auditory meatus
4 glenoid fossa 12 internal auditory meatus
5 mandibular condyle 13 mastoid process
6 articular tubercle 14 styloid process
2.13 Radiograph of the lateral view of tfi

bone.
1 posteroinferior limit of the middle cranial (
2 anterior limit of the posterior cranial fossi
3 internal auditory meatus
4 external auditory meatus
5 condylar neck
6 roof of glenoid fossa
7 articular tubercle
8 sigmoid notch of mandible
9 mastoid process
10 styloid process
11 atlas
30
Anatomy, Radiograpbic Anatomy and Cephalometrk Landmarks
At the central part of the petrous p o r t i o n , the At the lower part of the petrous portion of the
internal auditory meatus (3) can be identified as a temporal bone, the mastoid process (9) can be iden
round radiolucent area of 3 - 4 m m diameter. T h e tified as a radio-opaque area filled with radiolucent
internal auditory meatus lies 5 mm below the middle spots caused by the mastoid air cells. Inferior t o the
part of the anterosuperior surface of t h e petrous mastoid process, at the junction of the basioccipital
portion. The other radiohicenr area, with an oval- and the occipital condyle, the styloid process (10)
shaped diameter of 8 - 1 0 mm, which lies below and can be identified as a thin radio-opaque projection
anterior to the internal auditory m e a t u s , is the that directs d o w n w a r d s and forwards and crosses
external auditory m e a t u s (4). Its inferior third is t h e anterior surface of the atlas (11). This process
more radiolucent than its superior two thirds since becomes clearer in adults.
it is more aligned to the direction of the X-ray beam.
Anterior to the external auditory meatus are the Cephalometrk landmark (2.14)
condylar neck (5) and the roof of the glenoid fossa • Po - porion (anatomic) - the superior point of the
(6). The roof of the glenoid fossa appears as a thin external auditory meatus (the superior margin of
radio-opaque line between the endocranial surface the t e m p o r o m a n d i b u l a r fossa, which lies at the
of the petrous portion of the temporal bone and the same level, may be substituted in the construction
articular tubercle. T h e articular tubercle (7), identi of Frankfort horizontal) (bilateral).
fied as a half-oval radio-opaque area, lies above the
radiolucent area that represents t h e sigmoid notch
of the mandible (8).
2.14 Cephalometric landmark related

t o the temporal bone.
31
ETHMOID BONE terminates at the frontosphenoethmoidal suture (4).

Below the radio-opaque line of the cribriform plate
A n a t o m y (2.15) there is another radio-opaque line that represents
The ethmoid bone consists of a midline perpendic the superior wall of the maxillary sinus (5). Between
ular plate (1) that crosses the horizontal cribriform these two lines, there are radiolucent areas of fron-
plate (2). The perpendicular plate articulates pos- toethmoidal cells and cells of the lateral masses of
terosuperiorly with the sphenoid bone (3) and pos- the ethmoid bone (6). The posterior limit of the radi
teroinferiorly ir meets the vomer (4). The cribriform olucent area is the anterior surface of the sphenoid
plate articulates anterolaterally with the frontal body (7). In the same area can be seen greyish
bone (5) and posteriorly with the sphenoid bone. shadows of the superior and middle nasal conchae
Hanging off the outer lateral edge of the cribriform (8) superimposed on the radiolucent area of the
plate are the superior and middle nasal conchac (6,7). maxillary sinus.
Radiographic anatomy (2.16) Cephalometric landmarks (2.17)

The part of the ethmoid bone that can be identified • SE - sphenocthmoidal - the intersection of the
in the lateral cephalogram is the cribriform plate (I), shadows of the greater wing of the sphenoid and
which appears as a radio-opaque line below the hor the cranial floor as seen in the lateral cephalo-
izontal part of the internal cortical plate of the gram.
frontal bone (2). The anterior part of the line merges • Te - temporale - the intersection of the shadows
with the inferior surface of the internal surface of of the ethmoid and the anterior wall of the
the nasal bone (3), and the posterior part of the line infratemporal fossa (bilateral) (Sassouni).
2.15 Photograph of the ethmoid bone. 4 vomer bone

1 perpendicular plate of ethmoid bone 5 frontal bone
2 cribriform plate of ethmoid bone 6 superior nasal concha
3 sphenoid bone 7 middle nasal concha
32
2.16 Radiograph of the lateral view of the ethmoid

bone.
1 cribriform plate
2 internal cortical plate o f frontal bone '
3 nasal bone
4 frontosphenoethmoidal suture
5 superior wall of maxillary sinus
6 frontoethmoidal cells and cells of the lateral masses
of ethmoid bone
7 anterior surface of sphenoid bone
8 superior and middle nasal conchae
2.17 Cephalometric landmarks related

t o the ethmoid bone.
33
Orthodontic Cephahmtetry
NASAL BONES radio-opaque line of the cribriform plate of the

ethmoid bone (4).
Anatomy (2.18)
The nasal bones (1) are paired bones that lie in the Cephalometric landmarks (2.20)
midline above the nasal fossae between the frontal • FMN - frontomaxillary nasal suture - the most
processes of the maxilla (2). They articulate supe superior point of the suture where the maxilla
riorly with the frontal bone (3) at the frontonasal articulates with the frontal and nasal bones (uni
suture (4). lateral); unlike Na, FMN is on the anterior
cranial base, and it can therefore also be used for
Radiographic anatomy (2.19) measuring or defining the cranial base (Movers);
The nasal bone (1) appears as a triangular radio- • Na - nasion - the most anterior point of the fron
opaque area. Its apex points to the tip of the nose tonasal suture in the median plane (unilateral).
and its base faces the frontonasal suture (2), which
appears as an oblique radiolucent line between the
frontal (3) and nasal bones. The posterior part of
the inner surface of the nasal bone merges with the
2.I8 Photograph of the nasal bone. 3 frontal bone

1 nasal bone 4 frontonasal suture
2 frontal process of maxilla
2.19 Radiograph of the nasal bone.

1 nasal bone
2 frontonasal suture
3 frontal bone
4 cribriform plate
34
Anatomy, Radiographs Anatomy and Cephalometric Landmarks
2.20 Cephalometric landmarks related

to the nasal bone.
MAXILLA
Anatomy (2.21, p.37)

The maxilla consists of a large hollow b o d y that T h e palatine process (4) arises from the lower
houses the maxillary sinus (1) and four prominent edge of the medial surface of the body. Posteriorly
processes: it articulates with the horizontal plate of the palatine
• the frontal process (2); bone (9), forming the hard palate. At the posterior
• thezygomatic process (3); end of the hard palate, where the two horizontal
• the palatine process (4); and plates of the palatine bone meet in the midline, is the
• the alveolar process (5). posterior nasal spine (10). At the anterior one third
of t h e h a r d palate w h e r e t h e incisive canal (I I) is
The frontal process arises from the anteromedial presented, the upper surface of the hard palate turns
corner of the body of the maxilla and its medial rim upward as it extends anteriorly, forming the nasal
crest (12) for articulating with the vomer. The
fuses with the nasal bone (6). The maxillary bone is
anterior end of the nasal crest is t h e anterior nasal
connected superiorly with the frontal b o n e ( 7 ) ,
spine (13).
forming the medial orbital rim; posteriorly, it is con
nected with the lacrimal bone and the ethmoid bone Below the hard palate is the alveolar process (5),
(8), forming the medial orbital wall. housing the maxillary teeth. The deepest point in the
The zygomatic process (3) arises from the antero- midsagittal plane of the labial alveolar process is the
lateral corner and joins with the zygomatic b o n e , subspinale (14). The posterior limit of the alveolar
forming the infraorbital rim and the greater portion process is the maxillary tuberosity (15), forming the
of the orbital floor. anterior border ot the pterygomaxillary fissure (16).
35
Radiographic anatomy (2.22) labial aspect of alveolar process (16), which can be
Starting from the middle part of the face, the max identified as a curved radio-opaque line extending
illary sinus (1) is identified as a large radiolucent upwards from the cervical area of the maxillary
area surrounded by radio-opaque lines. The superior incisors, where the prosthion point (17) is located.
radio-opaque line is above the floor of the orbit (2). The subspinale (18) is identified as the deepest point
The inferior radio-opaque line is below the hard on this curved line between the anterior nasal spine
palate (3), especially at the anterior part. The pos (15) and the prosthion (17).
terior radio-opaque line is located 1-2 mm anterior The inferior border of the hard palate, forming
to the anterior wall of the pterygomaxillary fissure (4). the roof of the oral cavity (11), can be identified as
At the anterior wall of the maxillary sinus, the a radio-opaque line that becomes divergent as it
lacrimal canal (5) can be identified as a more radi extends anteriorly and merges with the lingual
olucent area with a boomerang-like shape; its apex aspect of the alveolar process (19).
faces backwards. In the middle of the maxillary-
sinus, the zygomatic process of the maxilla (6) can Cephalometric landmarks (2.23, p.38)
be identified as a triangular radio-opaque line with • A - Point A (or ss, subspinale) - the point at the
its apex facing the nasal floor. The upper part of the deepest midline concavity on the maxilla between
posterior border of the zygomatic process merges the anterior nasal spine and prosthion (unilater
with the posterior margin of the frontal process of al) (Downs);
the zygomatic bone (7). • Ans - anterior nasal spine (or sp, spinal point) -
At this point another horizontal radio-opaque this is the tip of the bony anterior nasal spine, in
line, which extends posteriorly, can be identified. the median plane (unilateral); it corresponds to
This represents the posterior part of the floor of the the anthropological point acanthion;
orbit (8). The lower part of the posterior and • APMax - anterior point for determining the
anterior borders of the zygomatic process join length of the maxilla - this is constructed by
together at the key ridge area (9). dropping a perpendicular from point A to the
Below the maxillary sinus is the hard palate (3), palatal plane (Rakosi);
whose anterior three quarters are formed by the • KR - the key ridge - the lowermost point on the
palatine process of the maxilla and whose posterior contour of the shadow of the anterior wall of the
quarter is formed by the horizontal part of the infratemporal fossa (bilateral) (Sassouni);
palatine bone. The hard palate (3) appears as two • Or - orbitale - the lowest point in the inferior
parallel radio-opaque lines; the upper line represents margin of the orbit, midpoint between right and
the floor of the nasal fossae (10) and the lower line left images (bilateral);
represents the roof of the oral cavity (11). At the • Pns - posterior nasal spine - the intersection of
posterior end, the two lines meet at the posterior a continuation of the anterior wall of the ptery-
nasal spine (12), where the inferior limit of the gopalatine fossa and the floor of the nose,
pterygomaxillary fissure (4) can be identified. The marking the dorsal limit of the maxilla (unilater
inferior limit of the pterygomaxillary fissure is a al); the point pterygomaxillare (pm), which rep
helpful reference area for identifying the posterior resents the dorsal surface of the maxilla at the
nasal spine (12) as it lies right above it. The two level of the nasal floor, also resembles landmark
parallel radio-opaque lines become divergent as they Pns; I
extend anteriorly. • Pr - prosthion (or superior prosthion or
At the anterior one third of the hard palate the supradentale) - the lowest and most anterior
incisive canal (13) can be identified as a radiolucent point on the alveolar portion of the premaxilla,
line descending obliquely from the superior surface in the median plane, between the upper central
of the hard palate to the lingual aspect of the max incisors (unilateral);
illary central incisor. This canal can be identified • Ptm - pterygomaxillary fissure - a bilateral
only in a patient with the permanent dentition. teardrop-shaped area of radiolucency, the
Anterosuperior to the nasal floor, there is a tri anterior shadow of which represents the poste
angular radio-opaque area representing the nasal rior surfaces of the tuberosities of the maxilla; the
crest (14); its anterior projection is the anterior nasal landmark is taken where the two edges, front and
spine (15). Below the anterior nasal spine is the back, appear to merge inferiorly.
36
2.21 Photograph of the lateral aspect (A) and medial aspect (B) 8 ethmoid bone
of the maxilla. 9 horizontal plate of palatine bone
1 maxillary sinus 10 posterior nasal spine
2 frontal process of maxilla 11 incisive canal
3 zygomatic process of maxilla 12 nasal crest
4 palatine process of maxilla 13 anterior nasal spine
5 alveolar process of maxilla 14 subspinale
6 nasal bone 15 maxillary tuberosity
7 frontal bone 16 pterygomaxillary fissure
2.22 Radiograph of the lateral view of the maxilla. 10 nasal floor

1 maxillary sinus I I roof of oral cavity
2 orbit 12 posterior nasal spine
3 hard palate 13 incisive canal
4 pterygomaxillary fissure 14 nasal crest
5 lacrimal canal 15 anterior nasal spine
6 zygomatic process of maxilla 16 labial aspect of alveolar process
' posterior margin of frontal process of zygomatic bone 17 prosthion
8 posterior part of floor of orbit 18 subspinale
9 key ridge 19 lingual aspect of alveolar process
37
()rth*nUmtk Cepbahmwtry
2.23 Cephalometric landmarks rela

ted t o the maxilla.
PALATINE B O N E S
A n a t o m y (2.24)
Kach palatine bone (1) is an irregular bone that Radiographic anatomy (2.25)
articulates between the maxilla (2) and the sphenoid rhe parts of the palatine bone identified in a lateral
bone (3). The palatine bones consist of a horizontal cephalogram arc:
plate and a vertical plate. The horizontal plates (1) • the posterior part of the hard palate (1);
meet in the midline and form the posterior part of • the posterior nasal spine (2);
the hard palate, and the posterior end of the hori • the pyramidal process (3), which forms the
zontal plates form the posterior nasal spine (4). anteroinferior part of the pterygoid fossa; and
• the sphenopalatine foramen (4), which is situated
at the roof of the pterygomaxillary fissure (5).
2.24 Photograph of the palatine bone.

1 horizontal plate of palatine bone
2 maxilla
3 sphenoid bone
4 posterior nasal spine
38
2.25 Radiograph of the lateral view of the palatine bone,

1 posterior part of hard palate
2 posterior nasal spine
3 pyramidal process of palatine bone
4 sphenopalatine foramen
5 pterygomaxillary fissure
NASAL CONCHAE

The nasal conchae are curved shelves of bone Above the posterior end of the middle nasal concha
covered by mucosa. They project from the lateral (2) is the sphenopalatine foramen (5). The nasal
nasal wall. They are divided into three parts accord conchae are separated from each other by the nasal
ing to their position: meatus (6).
• the inferior nasal concha (1) is the longest concha;
it lies near the nasal floor; Radiographic anatomy (2.27, p.40)
• the middle nasal concha (2) is almost as long as The inferior nasal concha (1), the middle nasal
the inferior nasal concha but it does not come concha (2), and the superior nasal concha (3) appear
quite as far forward; as light radio-opaque projections superimposed on
• the superior nasal concha (3) is about half the the radiolucent shadow of the maxillary sinus. The
length of the middle nasal concha; it lies above nasal meatus (4), which separates the nasal conchae
the posterior half of the middle nasal concha (2) from each other, can be identified as a radiolucent
anterior to the sphenoid sinus (4). line between the radio-opaque projections.
39
2.26 Photograph of the nasal concha.

1 inferior nasal concha
3 superior nasal concha
4 sphenoid sinus
5 sphenopalatine foramen
6 nasal meatus
2.27 Radiograph of the nasal concha.

1 inferior nasal concha
3 superior nasal concha
4 nasal meatus
ZYGOMATIC BONES
Anatomy (2.28) The frontal process (2) articulates with the frontal
Each zygomatic bone consists of a diamond-shaped bone (6) at the zygomaticofrontal suture (7),
body (1) and four processes: forming the lateral wall of the orbit. The temporal
• the frontal process (2); process (3) articulates with the zygomatic process of
• the temporal process (3); the temporal bone (8) at the zygomaticotemporal
• the maxillary process (4); and suture (9), forming the zygomatic arch. The maxil
• the jugular ridge (5). lary process (4) articulates with the zygomatic
40
process of the maxilla (10) at the zygomaticomax- Between the interior parts of the two lines, there is
illary suture (11), forming the infraorbital rim and another horizontal radio-opaque line, which rep
the orbital floor. The jugular ridge (5) is an eminence resents the maxillary process of the zygomatic bone
above the molar region; ir joins the maxilla at the (5). This line extends posteriorly and merges with
lateral wall of the maxillary sinus. the horizontal part of the zygomatic process of the
maxilla (6).
Radiographic a n a t o m y ( 2 . 2 9 )
The frontal process of the zygomatic bone (1) C e p h a l o m e t r i c l a n d m a r k s (2.30, p.42)
appears as two radio-opaque lines, one anterior and • Or - orbitale - the lowest point in the inferior
the other posterior. The anterior line is a curved line margin of the orbit, midpoint between right and
representing the anterior border of the lateral wall left images (bilateral).
of the orbit (2). The posterior line is a vertical line • Te - temporale - the intersection of the shadows
that extends downward from the junction with the of the ethmoid and the anterior wall of the
cribriform plate (3) and merges with the posterior temporal fossa (bilateral) (Sassouni).
border of the zygomatic process of the maxilla (4).
2.28 Photograph of the zygomatic bone.

1 zygomatic body
2 frontal process of zygomatic bone
3 temporal process of zygomatic bone
4 maxillary process of zygomatic bone
5 jugular ridge of zygomatic bone
6 frontal bone
7 zygomaticofrontal suture
8 zygomatic process of temporal bone
9 zygomaticotemporal suture
10 zygomatic process of maxilla
I I zygomaticomaxillary suture
2.29 Radiograph of the zygomatic bone.

1 frontal process of zygomatic bone
2 orbit
3 cribriform plate
4 posterior border of zygomatic process of maxilla
5 maxillary process of zygomatic bone
6 horizontal part of zygomatic process of maxilla
41
Orthodontic Cephalornetry

the zygomatic bone.
MANDIBLE
Anatomy (2.31)
The mandible is a horseshoe-shaped bone that mandibular foramen. The inferior dental canal
consists of a horizontal portion - the body (I) - and extends downwards and forwards, following the
the right and left vertical portions - the rami (2). curvature of the mandibular body to the mental
The posterior border of each ramus meets the foramen (6).
inferior border of the body at the mandibular angle
(3). The right and left sides of the mandibular body Radiographic anatomy (2.32, p.44)
meet each other at the chin point called the symph- Starting from the mandibular incisors, the most
ysis (4), on which there is an elevated area called the prominent incisor is traced. Anterior to the incisal
mental protuberance (5). On the superior aspect of root is a radio-opaque curve representing the
the body lies the alveolar process, which houses the external cortical plate of the symphysis (1). It curves
mandibular teeth. On the lateral surface of the posteriorly to the deepest part of the symphysis,
mandibular body there is the opening of the mental where the supramentale point (2) can be identified.
foramen (6), which lies below the premolar root This radio-opaque line then curves downwards and
area. forwards to the most prominent point, identified as
Posterior to the mental foramen is the external the pogonion point (3). The external cortical plate
oblique line, which passes posterosuperiorly to of the symphysis continues downwards and back
become the anterior border of the ramus, terminat wards to merge with the other radio-opaque line,
ing at the coronoid process (7). Posterior to the coro- which is posterior to the lingual aspect of the
noid process is the condylar process (8), which mandibular incisor and which represents the
articulates with the glenoid fossa of the temporal internal cortical plate of the symphysis (4).
bone (9). Lateral and posterior to the symphysis is the
At the centre of the medial surface of the ramus inferior border of the mandibular body, which can
there is the opening of the inferior dental canal - the be identified as a radio-opaque line that is usually
42
convex at the bicuspid area and concave at the antc- of the basilar part of the occipital bone (bilater
gonial notch. The inferior border of the mandibular al) (redefined by Coben after Bjork);
body meets the posterior border of the ramus at the B - Point B (or sm, supramentale) - the point at
angle of the mandible. the deepest midline concavity on the mandibu
The posterior border of the ramus extends up lar symphysis between infradentale and pogonion
wards and backwards to the condylar neck (5). It can (unilateral) (Downs);
be identified accurately up to the point where it is Co, condylion (or cd) - the most superior point
overlapped by the basisphenoid (6). In the lateral on the head of the condylar head (bilateral);
cephalogram, the condylar head is usually masked by Gn - gnathion - this is the most anteroinferior
either the ear-rod (7) or the basisphenoid (6). To point on the symphysis of the chin, and it is con
identify the condylar head more precisely, a lateral structed by intersecting a line drawn perpendic
cephalogram with the mouth open is recommended. ular to the line connecting Mc and Pog; however,
Anterior to the condyle is the coronoid process it has been defined in a number of ways, includ
(8), which appears as a triangular radio-opaque ing as the lowest point of the chin, which is syn
area. Its anterior border extends downward and onymous with menton;
merges with the anterior border of the ramus. Go - gonion - the constructed point of intersec
Between the condyle and coronoid process is the tion of the ramus plane and the mandibular
sigmoid notch (9), identified as a concave area. At plane;
the bicuspid area, the inferior dental canal (10) can Id - infradentale - the highest and most anterior
be seen as a radiolucent line extending upwards and point on the alveolar process, in the median
backwards along the curvature of the mandibular plane, between the mandibular central incisors
body to the centre of the ramus. (unilateral);
m - the most posterior point on the mandibular
Cephalometric landmarks (2.33, p.44) symphysis (unilateral);
• APMan - anterior landmark for determining the Me - menton - the most inferior midline point on
length of the mandible - it is defined as the per- the mandibular symphysis (unilateral);
pendicular dropped from Pog to the mandibular Pog - pogonion - the most anterior point of the
plane (Rakosi); bony chin in the median plane (unilateral);
• Ar - articulare - the point of intersection of the Pog' - pogonion prime - the point of tangency of
images of the posterior border of the condylar a perpendicular from the mandibular plane to the
process of the mandible and the inferior border most prominent convexity of the mandibular
symphysis (Coben).
2.31 Photograph o f the mandible.

1 mandibular body
2 mandibular ramus
3 mandibular angle
4 symphysis
5 mental protuberance
6 mental foramen
7 coronoid process
8 condylar process
9 glenoid fossa
43
2.32 Radiograph of the lateral view of the mandible. 6 basisphenoid

1 external cortical plate of the symphysis 7 ear-rod
2 supramentale 8 coronoid process
3 pogonion 9 sigmoid notch
4 internal cortical plate of the symphysis 10 inferior dental canal
5 condylar neck

the mandible.
44
Anatomy, Radiograpbic Anatomy and Cephalometric Landmarks
HYOID BONE
Anatomy (2.34)
The hyoid bone is a horseshoe-shaped bone sus to the body of the hyoid is the greater cornu (3),
pended in the neck. It consists of a body and two which appears as. a radio-opaque projection that
pairs of horns, the greater and lesser cornus. Each extends upwards and backwards to the cervical
greater cornu fuses with the body to form a free end area at the level of the third and fourth cervical
of the horseshoe. The lesser cornu projects superi vertebrae (4, 5). In children, the hyoid body (1)
orly at the junction of the body and the greater and the greater cornu (3) can be identified sepa
cornu. rately, whereas in adults these two parts are united.
Radiographic anatomy (2.35) Cephalometric landmark (2.36, p.46)

The body of the hyoid bone (I) appears as a radio- • hy - hyoid - the most superoanterior point on the
opaque, boomerang-shaped area situated inferior body of the hyoid bone (unilateral).
to the middle of the mandibular body (2). Posterior
2.34 Diagrammatic representation of the hyoid

LESSER CORNU bone.
GREATER CORNU
HYOID BODY
2.35 The hyoid bone in a

radiograph.
1 hyoid body
2 mandibular body
3 greater cornu
4 third cervical vertebra
5 fourth cervical vertebra
45
2.36 Cephalometric landmark related

t o the hyoid bone.
SUMMARY O F C R A N I O F A C I A L SKELETON dropping a perpendicular from point A to the

palatal plane (Rakosi);
Anatomy Ar - articulare - the point of intersection of the
The bones that make up the craniofacial skeleton images of the posterior border of the condylar
are shown in 2.37, p.48. process of the mandible and the inferior border
of the basilar part of the occipital bone (bilater
Radiographic anatomy al) (redefined by Coben after Bjork);
The radiographic appearance of the craniofacial B - Point B (or sm, supramentale) - the point at
skeleton is shown in 2.38, p.48. the deepest midline concavity on the mandibu
lar symphysis between infradentale and pogonion
Cephalometric landmarks (2.39, p.49) (unilateral) (Downs);
• A - Point A (or ss, subspinale) - the point at the Ba - basion - the median point of the anterior
deepest midline concavity on the maxilla between margin of the foramen magnum, located by fol
the anterior nasal spine and prosthion (unilater lowing the image of the slope of the inferior
al) (Downs); border of the basilar part of the occipital bone to
• Ans, anterior nasal spine (or sp, spinal point) - its posterior limit (unilateral) (Coben);
the tip of the bony anterior nasal spine, in the Bo - Bolton point - point in space (roughly at the
median plane (unilateral); it corresponds to the centre of the foramen magnum) that is located on
anthropological point acanthion; the lateral cephalometric radiograph by the
• APMan - anterior landmark for determining the highest point in the profile image of the post-
length of the mandible - this is defined as the per condylar notches of the occipital bone; since the
pendicular dropped from Pog to the mandibular postcondylar notches are close to the median
plane (Rakosi); sagittal plane, their shadows generally register on
• APMax - anterior point for determining the the lateral film as a single image (unilateral]
length of the maxilla - this is constructed by (Broadbent);
46
Anatomy, Radiograpbic Anatomy and Cephalometric Landmarks
• Cl -clinoidale - the most superior point on the point pterygomaxillare (pm), which represents the
contour of the anterior clinoid (unilateral); dorsal surface of the maxilla at the level of the
• Co-condylion (or cd) - the most superior point nasal floor, also resembles landmark Pns;
on the head of t h e condylar head (bilateral); • P o - porion (anatomic) - the superior point of the
• F - Point F (constructed) - the point a p p r o x i external auditory meatus (superior margin of
mating foramen caecum and representing the temporomandibular fossa which lies at the same
anatomic anterior limit of the cranial base, con level may be substituted in the construction of
structed as the point of intersection of a perpen Franfort horizontal) (bilateral);
dicular to the S-N plane from the point of • Pog - pogonion - the most anterior point of the
crossing of the images of the orbital roofs and the bony chin in the median plane (unilateral);
internal plate of the frontal bone (Coben); • Pog' - pogonion prime - the point of tangency of
• FMN - frontomaxillary nasal suture - the most a perpendicular from the mandibular plane to the
superior point of the suture, where the maxilla most p r o m i n e n t convexity of the m a n d i b u l a r
articulates with the frontal and nasal bones (uni symphysis (Coben);
lateral); unlike Na, F M N is on the anterior cranial • Pr - prosthion (or superior prosthion or
base, and it can therefore also be used for mea supradentale) - the lowest and most anterior
suring or defining the cranial base (Movers); point on the alveolar portion of the prcmaxilla;
• Gn - gnathion - the most anteroinferior point on it is in the median plane, between the upper
the symphysis of the chin; it is constructed by central incisors (unilateral);
intersecting a line drawn perpendicular to the line • Ptm - pterygomaxillary fissure - a bilateral
connecting M e and Pog; however, it h a s been teardrop-shaped area of radiolucency, whose
defined in a n u m b e r of ways, including as the anterior shadow represents the posterior surfaces
lowest point of the chin, which is s y n o n y m o u s of the tuberosities of the maxilla; the landmark is
with menton; taken where the t w o edges, front and back,
• Go-gonion - the constructed point of intersec appear to merge inferiorly;
tion of the ramus plane and the mandibular plane; • R O - roof of orbit - the uppermost point on the
• hy-hyoid - the most superoanterior point on the roof of the orbit (bilateral) (Sassouni);
body of the hyoid bone (unilateral); • S - sella - the point representing the midpoint of
• Id - infradentale - the highest and most anterior the pituitary fossa (sella turcica); it is a con
point on the alveolar process, in the median structed point in the median plane;
plane, between the m a n d i b u l a r central incisors • Sc - midpoint of the entrance to the sella - this
(unilateral); point represents the midpoint of the line con
• KR - the key ridge - the lowermost point on the necting the posterior clinoid process a n d the
contour of the shadow of the anterior wall of the anterior opening of the sella turcica; it is a t t h e
infratemporal fossa (bilateral); same level as the jugum sphenoidale and is inde
• m-the most posterior point on the mandibular pendent of the depth of the sella (Schwarz);
symphysis (unilateral); • SE - sphcnoethmoidal - the intersection of the
• Me- menton - the most inferior midline point on shadows of the great wing of the sphenoid and the
the mandibular symphysis (unilateral); cranial floor, as seen in the lateral cephalogram;
• Na - nasion - the most anterior point of the fron- • Si - floor of sella - the lowermost point on the
tonasal suture in the median plane (unilateral); internal contour of the sella turcica (unilateral);
• O p - opisthion - the posterior edge of foramen • SOr - supraorbitale - the most anterior point of
magnum (unilateral); the intersection of the shadow of the roof of the
• O r - orbitale - t h e lowest p o i n t in t h e inferior orbit and its lateral contour (bilateral) (Sassouni);
margin of the orbit, midpoint between right and • Sp - dorsum sellae - the most posterior point on
left images (bilateral); the internal contour of the sella turcica (unilateral);
• Pns - posterior nasal spine - the intersection of a • Te - temporale - the intersection of the shadows
continuation of the anterior wall of the ptery- of the ethmoid and the anterior wall of the
gopalatine fossa and the floor of the nose, marking infratemporal fossa (bilateral) (Sassouni).
the dorsal limit of the maxilla (unilateral); the
47
2.37 Photograph of the lateral aspect of

the craniofacial skeleton.
1 frontal bone
2 parietal bone
3 occipital bone
4 sphenoid bone
5 temporal bone
6 ethmoid bone
7 nasal bone
8 maxilla
9 zygomatic bone
10 mandible
2.38 Radiograph o f the lateral aspect of the craniofacial skeleton.

1 frontal bone
2 parietal bone
3 occipital bone
4 sphenoid bone
5 temporal bone
6 ethmoid bone
7 nasal bone
8 maxilla
9 palatine bone
10 zygomatic bone
I I mandible
48
Anatomy, Radiographic Anatomy and Cephalonwtric Landmarks
2.39 C e p h a l o m e t r i c landmarks of
craniofacial skeleton,
SOFT TISSUE PROFILE

The visible surface of the soft tissue facial profile Below the nasal base (9) is the philtrum (14) and the
extends from the hairline (trichion) (1) to the supe upper lip (15).
rior cervical crease (2). The three superposed levels In the inferior, mandibular level, there are the
mav be differentiated: lower lip (16) and the chin (17).
• rhe upper, frontal level, which belongs to the In a straight, harmonious profile, the nose, the
cranium and is located between the hairline (1) lips, and the chin have a balanced relationship. A
and the supraorbital ridge (3); line drawn from the glabella (5) to the most promi
• the middle, maxillary level, which is situated nent point of the chin (17) will intersect the middle
between the supraorbital ridge (3) and the of the nasal base (9). According to Ricketts (1968),
occlusal plane; and the lips are contained within the E line, the line from
• the inferior, mandibular level, which is located the tip of the nose (8) to the most prominent point
between the occlusal plane and the superior or the chin (17). The outlines of the lips are smooth
cervical crease (2). in contour. In relation to the E line, the upper lip
(IS) is slightly posterior to the lower lip (16) nnd the
In the upper, frontal level is the forehead (4), whose mouth can be closed without strain. According to
most prominent area is the glabella (5), and the Burstone et al (1978), anteroposterior lip position
supraorbital ridge (3). Variations in frontal protru can be also evaluated by drawing a line from sub-
sion in this area are due to frontal bossing, orbital nasale to soft tissue pogonion, and the amount of
hypoplasia, or both. lip protrusion or retrusion is measured as a per
In the middle, maxillary level, the profile extends pendicular linear distance from this line to the most
downwards and forwards from the root of the nose prominent point of both lips. In adults with har
(6) and the nasal bridge (7) to the tip of the nose (8), monious profiles and Class I occlusion, the most
then curves backward at the nasal base (9). In this prominent points of both upper and lower lips are
area, the nasal septum (10), the nostril (11), the ala usually 2-3 mm anterior to the line from subnasale
of the nose (12), and the cheek (13) can be seen. to soft tissue pogonion.
49
-*
There are many factors involved in lip protrusion. which is usually situated 10 mm behind and below
Lip disharmonies can be attributed either to incom the frontonasal suture. Below the eye is the contour
petent lip morphology (when the upper lip or the of the cheek (9), which can be identified as a radio-
lower lip or both are too short) or to functional opaque curve 1-2 mm behind the ala of the nose.
incompetence due to the protrusion of the upper
teeth. Variation in the inferior mandibular level is Cephalometric landmarks (2.42)
due to either a prominent chin or an absent chin. • G - glabella - the most prominent point in the
A prominent chin usually occurs in skeletal deep bite midsagittal plane of forehead;
patients, in whom the lower lip length is too long • Ils - inferior labial sulcus - the point of greatest
when compared to the lower facial height, thus concavity in the midline of the lower lip between
causing the curled appearance of the lower lip. labrale inferius and menton;
There is also a deep furrow between the lower lip • Li - labrale inferius - the median point in the
(16) and the chin (17). Absence of the chin usually lower margin of the lower membranous lip;
occurs in skeletal open bite patients when the lips • Ls - labrale superius - the median point in the
are forcibly closed and the mentalis muscle is dis upper margin of the upper membranous lip;
placed upwards. • Ms - menton soft tissue - the constructed point
For vertical facial relation, the harmonious profile of intersection of a vertical co-ordinate from
should have three equal areas: menton and the inferior soft tissue contour of the
• trichion (1) to lateral canthus (18); chin;
• lateral canthus (18) to the mouth (19); and • Ns - nasion soft tissue - the point of deepest con
• the curve of the ala of the nose (12) to the soft cavity of the soft tissue contour ot the root of the
tissue menton (20) (Ricketts, 1981). nose;
• Pn - pronasale - the most prominent point of the
Radiographic anatomy (2.41) nose;
The soft tissue profile appears as a light radio- • Pos - pogonion soft tissue - the most prominent
opaque area covering the bony structures of the point on the soft tissue contour of the chin;
face. It can be identified easily if the view box has • Sis - superior labial sulcus - the point of greatest
intense light and the bony structures are hidden by concavity in the midline of the upper lip between
black paper. The use of special filters during the subnasale and labrale superius;
radiological exposure of the patients can also • Sn - subnasale - the point where the lower border
provide a more clear imaging of the soft tissue of the nose meets the outer contour of the upper
profile in a lateral cephalogram. lip;
The soft tissue profile consists of the cutaneous • St - stomion - the midpoint between stomion
line of the forehead (1), the nasal bridge (2), the tip superius and stomion inferius;
of the nose (3), the base of the nose (4), the upper • Sti - stomion inferius - the highest point of the
and lower lips (5,6), the chin (7), and the throat. The lower lip;
other structures that can be identified are the eye (8), • Sts - stomion superius - the lowest point of the
the cheek (9), the ala of the nose (10), and the nostril upper lip.
( I I ) . The eye appears as a radiolucent area com
prising the upper and lower eyelids and the globe.
50
Anatomy, Radiographic Anatomy and Cephalometrk Landmarks
2.40 A n a t o m y o f t h e s o f t tissue
profile.
1 trichion
2 superior crease
3 supraorbital ridge
4 forehead
5 glabella
6 r o o t of the nose
7 nasal bridge
8 tip of the nose
9 nasal base
10 nasal septum
11 nostril
12 ala of the nose
13 cheek
14 philtrum
15 upper lip
16 lower lip
17 chin
18 lateral canthus
19 angle of the mouth
20 soft tissue menton
2.41 Radiograph of the

soft tissue profile.
1 forehead
2 nasal bridge
3 tip of the nose
4 base of the nose
5 upper lip
6 lower lip
7 chin
8 eye
9 cheek
10 ala of nose
1 1 nostril
2.42 Cephalometric landmarks related t o

the soft tissue profile.
SI
DENTITION R a d i o g r a p h i c a n a t o m y (2.44, p.54)

In the deciduous dentition (2.44A), the deciduous
A n a t o m y (2.43) teeth (1) appear as radio-opaque structures. Their
A specific characteristic of the development of the long axes are nearly perpendicular to the occlusal
dentition is that the crown of a tooth is calcified to plane and are parallel t o each other. The successors
the ultimate dimension before it emerges into the appear as r a d i o - o p a q u e follicles in the alveolar
oral cavity. The deciduous teeth emerge, while their bone. The p e r m a n e n t central incisors (2, 3) are
successors develop below. The eruption of the per situated lingually to the deciduous incisors (1). The
manent teeth mesial to the first molars is associated maxillary central incisors (2) lie beneath the nasal
with resorption of the roots of the predecessors and floor (4). Vertically the canines ( 5 , 6) are the teeth
their investing alveolar bone. that are placed furthest from the occlusal plane. The
In the deciduous dentition (2.43A), which usually maxillary canines (5) lie above or at the nasal floor
completes by the age of t w o and a half years, the (4). The mandibular canines (6) lie close to the lower
maxillary incisors (1) are related to the m a n d i b u - border of the mandibular body (7). The crowns o(
lar incisors (2) with an edge-to-edge bite. The buccal the bicuspids (8, 9) are formed beneath the roots
cusps of the maxillary molars ( 3 , 4) overlap the of the deciduous molars (10, 11). The first perma
buccal cusps of the m a n d i b u l a r molars ( 5 , 6). All nent molars (12, 13) are situated distally to the
maxillary teeth except the deciduous second molars deciduous second molars (11).
(4) occlude with the two opposing teeth. The distal In the mixed dentition (2.44B), the permanent
c o n t o u r s of the maxillary and m a n d i b u l a r second incisors (2, 3) e r u p t labially. Their inclination
molars (4, 6) are tangential to the perpendicular line relative t o the occlusal plane is more oblique than
of the occlusal plane. that of the deciduous incisors. The permanent
The mixed dentition (2.43B) begins with the canines (5, 6) erupt toward the roots of the perma
eruption of the permanent central incisors (7) and nent lateral incisors (14). The bicuspids (8, 9) erupt
the first molars (8, 9). The p e r m a n e n t central straight occlusally, corresponding with the resorp
incisors which are lingual to the predecessors erupt tion of the roots of the deciduous molars (10, 11).
in an oblique direction t o w a r d s the deciduous The first permanent molars (12, 13) drift mesially
incisors. After the exfoliation of the deciduous teeth, as they erupt into the oral cavity.
the p e r m a n e n t central incisors continue t o erupt In the p e r m a n e n t dentition (2.44C), all perma
labially a n d become upright later by the influence nent teeth erupt into the oral cavity. For cephalo-
of the opposing teeth and the musculature. Before metric analysis, the positions of the most prominent
the exfoliation of the deciduous second molars (4, incisors (2, 3) and the first molars (12, 13) are iden
6) the first permanent molars (8, 9) erupt with the tified. T h e maxillary incisors (2) lie between the
cusp-to-cusp relationship. labial and lingual aspects of the alveolar process (15,
In the permanent dentition (2.43C), all remain 16), which extend u p w a r d s from rhe cervical area
ing p e r m a n e n t teeth erupt a n d establish occlusal of the teeth a n d merge with the radio-opaque
contact with their counterpart teeth. The maxillary s h a d o w of the hard palate (17). T h e apex of the
teeth overlap the m a n d i b u l a r teeth in buccolabial central incisor is helpful in identifying the subspinale
direction. In centric occlusion all maxillary teeth point as it usually lies posterior to this point. The
except the central incisors occlude half a tooth distal first maxillary molars (12) are situated below the
to their opposing teeth. In normal occlusion the key ridge (18). Their apices may be masked by the
mesiolingual cusp of the maxillary first molar (8) shadow of the hard palate (17), by the inferior wall
occludes with the central fossa of the m a n d i b u l a r of the maxillary sinus (19), or by both these struc
first molar (9). tures. The mandibular incisors (3) lie between the
external and the internal cortical plates of the sym-
physis (20, 21). The apex of the mandibular incisor
is a helpful area to identify the supramentale point
as it usually lies posterior to and slightly above the
supramentale point.
52
Anatomy, Radiographk Anatomy and Cepbalometrk Landmarks
Cephalometric l a n d m a r k s (2.45, p.54) Isi - incision superius incisalis - the incisal edge
1
APOcc - anterior point for the occlusal plane - a of the maxillary central incisor;
constructed point, the m i d p o i n t of the incisor LI - mandibular central incisor - the most labial
overbite in occlusion; point on the c r o w n of the m a n d i b u l a r central
• Iia - incision inferius apicalis - the root apex of incisor;
the most anterior mandibular central incisor; if L6 - m a n d i b u l a r first molar - the tip of the
this point is needed only for defining the long axis mesiobuccal cusp of the mandibular first perma
of the tooth, the midpoint on the bisection of the nent molar;
apical root width can be used; PPOcc - posterior point for the occlusal plane -
• Iii - incision inferius incisalis - the incisal edge of the most distal point of contact between the most
the most prominent mandibular central incisor; posterior molars in occlusion (Rakosi);
• Isa - incision superius apicalis - the root apex of III - maxillary central incisor - the most labial
the most anterior maxillary central incisor; if this point on the c r o w n of the maxillary central
point is needed only for defining the long axis of incisor;
the tooth, the midpoint on the bisection of the U6 - maxillary first molar - the tip of the
apical root width can be used; mesiobuccal cusp of the maxillary first permanent
molar.
2.43 Anatomical characteristics of natural deciduous dentition

(A), mixed dentition (B) and permanent dentition (C).
1 deciduous maxillary incisor
2 deciduous mandibular incisor
3 deciduous maxillary first molar
4 deciduous maxillary second molar
5 deciduous mandibular first molar
6 deciduous mandibular second molar
7 permanent maxillary central incisor
8 permanent maxillary first molar
9 permanent mandibular first molar
53
Orthodontic Cephaiometry
2.44 Radiographic anatomy of natural deciduous dentition (A), mixed dentition (B) and
permanent dentition (C).
1 deciduous incisor
2 permanent maxillary central incisor
3 permanent mandibular central incisor
4 nasal floor
5 permanent maxillary canine
6 permanent mandibular canine
7 lower border of the mandibular body
8 first bicuspid
9 second bicuspid
10 deciduous first molar
I I deciduous second molar
12 permanent maxillary first molar
13 permanent mandibular first molar
14 permanent lateral incisor
15 labial aspect of the alveolar process
16 lingual aspect of the alveolar process
17 hard palate
18 key ridge
19 inferior wall of maxillary sinus
20 external cortical plate of symphysis
21 internal cortical plate of symphysis
2.45 Cephalometric landmarks related to the

dentition.
54
PHARYNX part of the ramus (3) and terminates at the level of

the inferior border of the sixth cervical vertebra (4)
Anatomy (2.46, p.56) where it is continuous with the oesophagus.
The pharynx is a median fibromuscular tube that At the roof and the upper part of the posterior
extends from the base of the skull. Jt is made up wall of the pharyngeal space, the adenoid (5) can be
from the sphenoid (1) and the occipital bones (2) to identified as a radio-opaque mass extending
the level of the sixth cervical vertebra (3), where it between the inferior surface of the sphenoid body
is continuous with the oesophagus (4). The pharynx (1) and the anterior arch of the atlas (6), which
is open anteriorly to the nasal cavity (5), the oral appears as a triangular radio-opaque area.
cavity (6), and the larynx (7). It is divided into three Anterior to the adenoid is the pharyngeal space
parts: the nasopharynx, the oropharynx, and the of the nasopharynx (7). This is a boomerang-
laryngopharynx. shaped, radiolucent area that extends from the
inferior surface of the sphenoid bone to the superior
Nasopharynx surface of the soft palate. The soft palate (8) appears
The nasopharynx (8) is the upper part of the as a light radio-opaque area with a boomerang
pharynx. It is situated behind the oral cavity (6) shape. It projects downward and backward from the
above the soft palate (9). Its superior border is the posterior part of the hard palate (9). Inferior to the
base of the skull (1, 2). In the posterior part of the soft palate is the palatine tonsil (10), which is a light
roof and the upper part of the posterior wall, there radio-opaque oval area.
is an accumulation of lymphoid tissue - the adenoid Below the soft palate (8) and the palatine tonsil
or pharyngeal tonsil (10) - which may be prominent (10) is the tongue (11), identified as a radio-opaque
in children but which becomes indistinct in adult curve extending to the level of the hyoid bone (12).
hood. In the lateral wall, 1.5 cm posterior to the Posterior to the pharyngeal part of the tongue (11)
inferior nasal concha (11), is the opening of the is the epiglottic fossa (13), seen as a triangular radi
udirory tube (12). The nasopharynx (8) extends olucent area. The epiglottic fossa separates the pha
downwards and is continuous with the oropharynx ryngeal part of the tongue (11) from the epiglottis
■(13) at the level below the soft palate (9). (14), which appears as a triangular radio-opaque area.
The radiolucent area between the soft palate (8)
Ore-pharynx and the superior surface of the epiglottis (14) is the
The oropharynx (13) is the middle part of the pharyngeal space of the oropharynx (15). Below the
pharynx situated between the soft palate (9) and the epiglottis (14) is the pharyngeal space of the laryn
superior border of the epiglottis (14). Anteriorly it gopharynx (16), which can be identified as a radi
is open to the oral cavity (6) and is bordered by the olucent area extending to the level of the sixth
posterior one third of the tongue (15). At the lateral cervical vertebra (4). When roentgenocephalomet-
boundaries of the opening of the oral cavity (6) into ric evaluation of the tongue is intended, its midline
the oropharynx (13), the palatine tonsils are lodged should be coated with a radio-opaque paste
inthetonsilar fossae. (Oesophague paste) for better imaging (lngervall
andSchmoker, 1990).
larpgopharynx
The laryngopharynx (16) is the lower part of the Cephalometric landmarks (2.48, p-57)
pharynx. It extends from the superior border of the • ans - anterior nasal spine;
epiglottis (14) to the inferior border of the sixth • apw - anterior pharyngeal wall;
ervical vertebrae (3), where it becomes continuous • hy - hyoid;
'th the oesophagus (4). The upper part of the • pns - posterior nasal spine;
aryngopharynx (16) is open anteriorly to the larynx • ppw - posterior pharyngeal wall;
7} via the patent inlet. • pt - posterior point of tongue;
• ptm - pterygomaxillary fissure;
Radiographic anatomy (2.47, p.56) • spw - superior pharyngeal wall;
'tarring from the junction of the anterior and • U - tip of uvula;
inferior surfaces of the sphenoid body (1), the roof • Uo - point on the oral side of the soft palate;
nd the posterior wall of the pharyngeal tract • U p - point on the pharyngeal side of the soft
ppear as a radio-opaque line that descends anterior palate;
the cervical vertebrae (2). It crosses the middle • ut - upper point of tongue.
55
2.46 Anatomy of pharynx.

1 sphenoid bone
2 occipital bone
3 the sixth cervical vertebra
4 oesophagus
5 nasal cavity
6 oral cavity
7 larynx
8 nasopharynx
9 soft palate
10 adenoid o r pharyngeal tonsil
1 1 inferior nasal concha
12 opening of the auditory tube
13 oropharynx
14 epiglottis
15 tongue
16 iaryngopharynx
2.47 Radiographs of the pharynx

1 sphenoid bone
2 cervical vertebra 10 palatine tonsil
3 mandibular ramus I I tongue
4 the sixth cervical vertebra 12 hyoid bone
5 adenoid 13 epiglottic fossa
6 anterior arch of the atlas 14 epiglottis
7 nasopharynx 15 oropharynx
8 soft palate 16 Iaryngopharynx
9 hard palate
56
Anatomy, Radiographic Anatomy and Cepbalometric Landmarks
2.48 Cephalometric landmarks related t o the pharynx.
ans
CERVICAL VERTEBRAE
The first and second cervical vertebrae (Cl and
Anatomy (2.49, p.59) C2) have distinctive morphology. The first cervical
Thecervical vertebrae make up the upper part of the vertebra (Cl) is known as the atlas (2.49B). It is the
vertebral column. There are seven cervical vertebrae only vertebra that has no body, and thus the spinous
(C1-C7). A typical cervical vertebra (2.49A) processes of Cl form a ring bone. The vertebral arch
consists of a body and a vertebral arch. can be divided into two parts: the anterior arch and
The body (1) is the anterior part of the vertebra. the posterior arch.
It resembles a segment of an ovoid rod. The verte The anterior arch (8) has the anterior tubercle (9)
bral arch attaches posteriorly to the body and sur for muscular attachment. The posterior arch (10)
rounds the spinal cord. Each arch consists of two has the posterior tubercle (11) instead of the spinous
pedicles and two laminae. The pedicles (2) arise process. The superior articular facets (12) are
from posterolateral aspects of the body (1). The concave with a kidney shape for the reception of the
laminae (3) spring from the pedicles. On each side occipital condyles of the skull. The inferior articu
of the junction between the pedicle (2) and the lar facets (13) are round and almost flat for articu
lamina (3) is a transverse process projecting later lation with the second cervical vertebra. In the
ally. The transverse processes (4) of the cervical ver lateral mass there is the transverse foramen (5).
tebrae each have a characteristic transverse foramen The second cervical vertebra (C2), known as the
(S), which transmits the vertebral artery to the brain. axis (2.49C), is characterized by the presence of the
At the junction of the pedicle (2) and the lamina (3) dens or odontoid process. The dens (14) is a tooth-
are the superior articular process and inferior artic like process that projects superiorly from its body
ular process, which bear articular facets (6) that (1) and articulates with the anterior arch of the atlas.
form synovial joints with the adjacent vertebrae. At The process represents the transposed body of the
the meeting of the two laminae (3), there is a spinous atlas and acts as the pivot around which the atlas
process (7) that projects posteriorly. rotates.
57
The remaining cervical vertebrae (C3-C7) intervertebral disc space (18), which appears as a
(2.49D) have the basic components of typical ver radiolucent strip. At the midpoint between the third
tebrae and closely resemble each other. The size of and the fourth cervical vertebrae is the hyoid bone
these vertebrae increases caudally as they extend (19), which is situated anteriorly.
from the occipital condyles (15) to the thoracic ver
tebrae (16). C e p h a l o m e t r i c landmarks (2.51, p . 6 l )
• cv2ap - the apex of the odontoid process of the
Radiographic anatomy (2.50, p.60) second cervical vertebra;
Anteroinferior to the occipital condyle (1), which • cv2ip - the most inferoposterior point on the
appears as a curved radio-opaque line, the anterior body of the second cervical vertebra;
arch of the atlas (2) can be identified as a small tri • cv2ia - the most inferoanterior point on the body
angular radio-opaque area. The apex of the triangle of the second vertical vertebra;
faces the posterior border of the mandibular ramus • cv3sp - the most superoposterior point on the
(3), while its base faces the odontoid process of the body of the third cervical vertebra;
axis (4). The central mass of the atlas, which bears • cv3ip - the most inferoposterior point on the
the inferior articular facet (5), appears as a radio- body of the third cervical vertebra;
opaque area superimposed on the radio-opaque • cv3sa - the most superoanterior point on the
shadow of the odontoid process (4). Posterosuperior body of the third cervical vertebra;
to the inferior articular facet (5) is the superior artic • cv3ia - the most inferoanterior point on the body
ular facet (6), which can be identified as a radio- of the third cervical vertebra;
opaque area. Its superior border is concave and • cv4sp - the most superoposterior point on the
corresponds with the contour of the occipital condyle body of the fourth cervical vertebra;
(1). Next to the superior articular facet is the poste • cv4ip - the most inferoposterior point on the
rior arch (7) with the posterior tubercle (8). At the body of the fourth cervical vertebra;
superior border of the posterior arch (7) is a groove • ev4sa - the most superoanterior point on the
for the vertebral artery and the first cervical nerve (9). body of the fourth cervical vertebra;
The odontoid process (4) and the body of the axis • cv4ia - the most inferoanterior point on the body
(10) appear as a triangular radio-opaque area. The of the fourth cervical vertebra;
odontoid process (4) represents the apex of the tri • cv5sp - the most superoposterior point on the
angular points toward the occipital condyle (I). The body of the fifth cervical vertebra;
spinous process of the axis (11) appears as a radio- • cv5ip - the most inferoposterior point on the
opaque projection extending posteriorly. body of the fifth cervical vertebra;
The radiographic appearances of the third • cv5sa - the most superoanterior point on the
cervical vertebra (C3) to the seventh cervical body of the fifth cervical vertebra;
vertebra (C7) are similar. The body of each of these • cv5ia - the most inferoanterior point on the body
cervical vertebrae (12) appears as a wedge-shaped of the fifth cervical vertebra;
radio-opaque area situated behind the pharyngeal • cv6sp - the most superoposterior point on the
space (13). Posterior to the body is the spinous body of the sixth cervical vertebra;
process (14). The transverse processes (15), the • cv6ip - the most inferoposterior point on the
superior articular process (16) and the inferior artic body of the sixth cervical vertebra;
ular process (17) appear as a radio-opaque area • cv6sa - the most superoanterior point on the
superimposed on the shadow of the body (12) and body of the sixth cervical vertebra;
the spinous process (14). The body of each cervical • cv6ia - the most inferoanterior point on the body
vertebra is separated from the adjacent ones by the of the sixth cervical vertebra.
58
Anatomy, Radiographic Anatomy and Cepbalometric Landmarks
B(a)
B(b)
2.49 Anatomy of the cervical vertebrae. (A) Typical cervical 7 spinous process
vertebra. (B) The first cervical vertebra (atlas) (a and b). (C) The 8 anterior arch of the atlas
second cervical vertebra (axis). (D) The lateral aspect of the 9 anterior tubercle
cervical vertebrae (CI-C7). 10 posterior arch of the atlas
1 body I I posterior tubercle
2 pedicle 12 superior articular facet
3 lamina 13 inferior articular facet
4 transverse process 14 dens or odontoid process of the axis
5 transverse foramen 15 occipital condyle
6 articular facet 16 thoracic vertebra
59
2.50 Radiograph of the lateral aspect of the cervical vertebrae (A 9 groove for the vertebral artery and the first cervical nerve
and B) (B r e p r o d u c e d by courtesy o f D r E Hellsing, Hudinge, 10 body of the axis
Sweden). 11 spinous process of the axis
1 occipital condyle 12 body of the third cervical vertebra
2 anterior arch of the atlas 13 pharyngeal space
3 mandibular ramus 14 spinous process of the third cervical vertebra
4 dens o r o d o n t o i d process of the axis 15 transverse process
5 inferior articular facet 16 superior articular process
6 superior articular facet 17 inferior articular process
7 posterior arch 18 intervertebral disc space
8 posterior tubercle 19 hyoid bone
60
Anatomy, Radiographic Anatomy and Cephalometrk Landmarks
2.5 I Cephalometrk landmarks of the cervical

vertebrae.
cv2ip
cv2ia V\.^*** cv3sp
c v 3 s a ^ V cv3 . p
<*3taWVlw4sp
cv4sa f \
cv4ia * ^ Z - ^ | cv5sp
cv5sa p
J . \ cv5ip
cv5iat^_^^ c v 6 s p
cv6sar^" /
Cv6ia£ -* cv6ip
REFERENCES
Athanasiou AE, Toutountzakis N , Mavreas D, Ritzau Coben SE (1986) Basion Horizontal: An Integrated
M, Wenzel A (1991) Alterations of hyoid bone Concept of Craniofacial Growth and Cephalometric
position and pharyngeal depth and their relationships Analysis. (Computer Cephalometrics Associated:
after surgical correction of mandibular prognathism. Jenkintown, Pennsylvania.)
Am] Orthod Dentofacial Orthop 100:259-65.
Downs WB (1948) Variations in facial relations:
Bjork A (1947) The face in profile. Suenska Tandlak their significance in treatment and prognosis. Am
TW40(suppl5B):32-3. J Orthod 34:812-40.
Broadbent BH Sr, Broadbent BH Jr, Golden W H DuBrul EL (1980) Sicher's Oral Anatomy. (CV
(1975) Bolton Standards of Dentofacial Mosby: St Louis.)
Developmental Growth. (CV Mosby: St Louis.)
Gjorup H, Athanasiou AE (1991) Soft-tissue and
Burstone CJ (1958) The integumental profile. Am dentoskeletal profile changes associated with
| J Orthod 44:1-25. mandibular setback osteotomy. Am J Orthod
Dentofacial Orthop 100:312-23.
Burstone CJ, James RB, Legan H, iMurphy GA,
Norton L (1978) Cephalometrics for orthognathic Graber T M (1972) Orthodontics, Principles and
surgery. / Oral Surg 36:269-77. Practice. (WB Saunders: Philadelphia.)
Coben SE (1955) The integration of facial skeletal

variants. Am J Orthod 41:407-34.
I 61
Orthodontic Cepbalotnetry
Hellsing E (1991) Cervical vertebral dimensions in Movers RE (1988) Handbook of Orthodontics.

8-, 11-, and 15-year-old children. Ada Odontol (Year Book: Chicago.)
Scand 49:207-13.
Rakosi T (1982) An Atlas and Manual of
Holdaway RA (1983) A soft-tissue ccphalometric Cepbalometric Radiography. (Wolfe: London.)
analysis and its use in orthodontic treatment
planning. Part L Am) Orthod 84:1-28. Ricketts RM (1968) Esthetics, environment and the
law of lip relation. Am J Orthod 54:272-89.
Ingervall B, Sehmoker R (1990) Effect of surgical
reduction of the tongue on oral stereognosis, oral Ricketts RM (1981) The Golden Divider. / Clin
motor ability, and the rest position of the tongue and Orthod 15:725-59.
mandible. Am / Orthod Dentofacial Orthop
97:58-65. Sassouni V (1955) Roentgenographic cephalomet
ric analysis of eephalo-facio-dental relationships.
Jacobson A, Caufield PW (1985) Introduction to Am J Orthod 41:734-42.
Radiographic Cephalometry. (Lea and Febiger:
Philadelphia.) Schwarz AM (1937) Lehrgang der Gebessregelung.
Ill Die schadelbezugliche Uniersuchung. IV Der
Mazaheri M, Krogman W M , Harding RL, Millard schddelbezugliche Befund. (Urban and Schwarzen-
RT, Mehta S (1977) Longitudinal analysis of growth berg: Berlin.)
of the soft palate and nasopharynx from six months
to six years. Cleft Palate J 14:52-62. Solow B, Tallgren A (1971) Natural head position
in standing subjects. Ada Odontol Scand
McMinn R M H , Hutchings RT (1977) A Colour 29:519-607.
Atlas of Human Anatomy. (Wolfe: London.)
Solow B, Tallgren A (1976) Head posture and cran-
Melsen B, Athanasiou AE (1987) Soft Tissue iofacial morphology. Am j Rhys Anthropoi
Influence in the Development of Malocclusion. (The 44:417-36.
Royal Dental College: Aarhus.)
Steiner CC (1962) Cephalometrics as a clinical tool.
In: Kraus BS, Riedel RA (eds) Vistas in
Orthodontics. (Lea and Febiger: Philadelphia)
131-61.
62
CHAPTER 3
Possibilities and Limitations of Various Cephalometric

Variables and Analyses
Rainer-Reginald Miethke
INTRODUCTION A N D GENERAL Before describing the specific measurements that

CONSIDERATIONS are, in our opinion, meaningful, it is useful to
describe how our analysis developed. The author of
If we assume that cephalometric analyses are this chapter started his training in a traditional
valuable rools in the comprehensive diagnosis of German orthodontic department where patients
malocclusions and skeletal malformations, it would were treated only with removable appliances. The
be logical to choose the ideal analysis from among head of the department was very active scientifical
the existing ones. The next questions to arise are: ly and, therefore, had used cephalometric evaluation
Do we do this? Do we really select the best cephalo from the beginning of his academic carreer. To inten
metric analysis of all? How do we decide that our sify his knowledge in this area, he once had traced
method is superior to the rest? What are the short cephalograms taken from 400 skulls and analysed
comings of the ones we decide not to use? them using Schwar/.'s method (Schwarz, 1937) (3.1).
If we answer with honesty the main question - After this and other experiences, he came to the con
why we choose 'our' cephalometric analysis and not clusion that the individual variability of all para
any other - we generally have to admit that we do meters was so large that cephalometric measurements
not decide; rather the decision is more or less forced could not help him significantly with the ortho
on us. We had instructors before, during, or after dontic diagnosis of individual patients. He taught
our postgraduate training who convinced us in one us the Schwarz analysis but without great enthusi
way or the other that they had the answer to the key asm.
question of which method of cephalometric evalu Our next exposure to ccphalometrics occurred
ation is best. We followed their advice - not a sci when we attended the first fixed appliance course,
entific approach to the solution of the given which was given in Berlin in 1971. There we were
problem! acquainted very systematically with a method called
Still, this seems to be the only feasible approach the 'Bergen analysis' (Hasund, 1974) only to find
because none of us can study, use, and gain suffi out later that it was basically nothing else than a
cient experience with all the existing analyses to be slightly modified Steiner analysis.
able to make a fully informed decision as to which Because the author felt his training in fixed appli
is the best system. Anyone who attempted this ances would never become adequate through
would have retired from orthodontics before he had attending continuing education courses, he went to
come to the final conclusion. the USA, the motherland of this treatment modality.
Let us come back to the basic question of which There he learnt and practised many different
is the best cephalometric analysis. The only true analyses. Routinely the department there used the
answer probably is: None or several! If one system analyses of Steiner (1953, 1960) and Downs (1948,
of analysis was absolutely superior to all the others, 1952, 1956). After returning to Germany, the
then it is likely that every responsible, knowledge author used these two analyses; however, gradual
able orthodontist would have decided to use this ly the original evaluations expanded. Influenced by
method exclusively. Since this is not the case, it lectures, courses, articles, and even discussions with
seems more likely that several evaluation methods colleagues, measurements of Jacobson (1975,1976),
for cephalometric X-rays are appropriate, ejpecial- Bjork (1947), Jarabak and Fizzell (1972), and
\l if they are used with common sense, experience, Hasund (Hasund et al, 1984) were added. So finally
and some critical distance. we seemed to have a very thorough and compre
hensive cephalometric analysis.
63
When the forms for this composite analysis had general agreement. At the same time, w e also
t o be reprinted, the a u t h o r t o o k a closer look at decided to bring all measurements into a more
them and realized that some measurements meant logical order and also t o add a graphical represen
more t o him than o t h e r s , and t h a t he primarily tation to the numerical analysis. The analysis thus
checked certain parameters to determine a patient's developed has been in use since then with only slight
problem. Because of this, the question of which modifications.
cephalometric parameters were the most useful was Before starting with cephalometrics, the clinician
discussed in a circle of experienced clinicians. It should consider the basic problem of whether to
turned o u t not t o be t o o difficult to c o m e t o a analyse cephalograms in the traditional way or in
3.1 Cephalometric analysis of Schwarz (1937)

w i t h r e s p e c t i v e average v a l u e s . T h e basic
reference line is the Frankfort horizontal plane,
which is labelled here as O A (Ohr-Augebene:
ear-eye plane).
3.2 Reference p o i n t s w h i c h w e r e d i r e c t l y digitized ( A ) o r 666 children and adolescents by Droschl (1984). (From Droschl,
calculated by the computer (B) during a cephalometric screening of 1984; reprinted with permission.)
64
Possibilities and Limitations of Variables and Analyses
a more modern way using electronic data process Another general question is: H o w do we interpret
ing (ED P). T h e general d e v e l o p m e n t goes t o t h e t h e results w e have gained t h r o u g h a cephalomet
inclusion of cephalometric analyses in EDP ric analysis? Commonly this is done by comparing
programs or p r o g r a m packages. But sometimes a the measurements of an individual patient with ideal
problem arises because the only programs that are or average values. However, a serious problem with
available are those developed by famous o r t h o d o n such d a t a is that one seldom k n o w s exactly w h a t
tists. If one of these analyses is identical with the inclusion criteria were used for the study from
buyer's idea, the constellation is perfect. A problem which the values for o u r c o m p a r i s o n are finally
arises, however, if the customer w a n t s to have a derived. Did they use patients with ' n o r m a l ' or
slight change in a marketed EDP analysis because 'ideal' occlusions? Since it is possible t o have a
many of the programs are inflexible. N o t all of the ' g o o d ' occlusion and yet still have an unattractive
big companies are willing to help or to give the user appearance, was this aesthetic aspect included in the
a possibility of changing the p r o g r a m himself. selection process? What was the age of the sample
Fortunately, this situation is becoming better, with and did it consist equally of both sexes? When was
an increase in the number of smaller companies that t h e s a m p l e collected; can w e a s s u m e t h a t average
care for personalized service, thus increasing the skull-face-dentition dimensions have not changed
competition. Finally, a n o t h e r alternative is to since then? A final question especially important for
develop an individual EDP cephalometric evaluation any orthodontist outside the USA is: H o w does my
that satisfies all personal ideas of an optimal population correspond with a sample which stems
program. from N o r t h America? But even within the USA this
That was what we did. Since preferences can problem exists, since there are some remarkable dif
change because of scientific progress, the program ferences between individuals in the n o r t h a n d t h e
was structured in such a way that additions or omis south (Taylor and Hitchcock, 1966).
sions can be easily accomplished. W i t h o u t being Droschl (1984) proposed a solution t o this
able to give any final advice t o a colleague w h o problem (3.2). H e evaluated Austrian children of
starts with o r t h o d o n t i c s a n d has to make the both sexes aged between six and 15. At 15, patients
decision to purchase a cephalometric EDP program, are considered as adults, though we k n o w by more
we would like him t o a c k n o w l e d g e a t least this recent studies t h a t g r o w t h c o n t i n u e s even beyond
problem and strive for its best solution under his this age (Behrents, 1989) (3.3). Droschl also
personal conditions. proposed cephalometric values for patients with
3.3 G r o w t h of an individual between 17 and 41 years as observed

by Behrents (1989). This adult's g r o w t h is expressed as a forward
rotation of the mandible (as well as the chin), which is typical in
males. T h e r e is always an increased p r o m i n e n c e of the nose,
independent of the patient's sex. (From Behrents, 1989; reprinted
w i t h permission.)
65
[
Orthodontic Qephalomeiry
Class II, Division 1 malocclusions. Since his sample demonstrated a relative stability of its size over time,
is well defined and is one that can be considered to we kept it constant for all age groups and only dif
be very close to the population of our area in central ferentiated between males and females.
Europe, it became the basis for the comparison data When using our cephalomerric analysis program,
of our analysis (Table 3.1). it will ask first for the name of the patient, his date
One problem remained in that, although Droschl of birth, his sex, and the date the cephalometric X-
had measured many parameters, he had not ray was taken in order to correlate the patient's data
included several that are part of our analysis. with the appropriate norm data.
However, as cephalomctrics is, to a large degree, Furthermore, the computer program corrects the
applied geometry, it was possible to deduce the measured values in relacion to the true vertical
missing measurements from other measurements, plane, which is by definition a plane perpendicular
though admittingly in a few cases approximations to the plane of the horizon of the earth (true hori
had co be made. At the end of this process, we had zontal). (It is the impression of the present author
data for comparison that marched our patients opti that the problem of the true vertical plane is often
mally as far as population, sex, and age were con made more complicated than necessary. With a flat
cerned. The only exception is the 'second floor and a cephalostat set up in a regular rectan
generation* Holdaway soft tissue angle (Holdaway, gular fashion, the lower border of the cassette or the
1983; Schugg, 1985), which has not been formally X-ray image is parallel to the true horizontal.
evaluated for a (central) European population, but Consequently, the anterior and posterior margins of
which has been at least roughly adopted to age and the X-ray cassette reflect the true vertical.)
gender by Zimmer and Miethke (1989). A This seems to be very reasonable and is acknowl
somewhat similar problem occurred with the age edged by several prominent orthodontic scientists
dependence of the Wits appraisal. However, since (e.g. Moorrees and Kean; 1958, Viazis, 1991;
a study by Bishara and Jakobsen (1985) (3.4) Lundstrom and Lundstrom. 1992).
Wits
Absolute Curvet for Mate* Absolute Curves for Females
10 ■ >o
• •
I
*...*..••" "♦"•■•♦..Jt
-5 ■
-T- T- T-V/-
5 7 11 13 15 IT
AGE AGE
© LFT • AfT m SFT * © LFT AFT SFT 1
3.4 The change of the W i t s appraisal over time for males and Basically, the W i t s appraisal is stable, especially in girls. Though
females as found by Bishara and Jakobsen (1985). males show a somewhat more obvious increase in the second half
LFT - long face type of t h e i r teenage years, the values r e t u r n later almost to their
A F T - average face type original level. (From Bishara and Jakobsen, 1985; reprinted with
SFT - short face type. permission.)
66
Table 3.1 Cephalometric standard values for all variables of the presented analysis. The upper horizontal column is indicating the
respective age; the column on the very right gives the standar deviation. The first horizontal line is valid for males, the second for females.
(Forfurther details, see Zimmer and Miethke, 1989).
67
W H Y USE CEPHALOGRAMS? patients are interested in their profile, i.e. in the

relative prominence of the maxilla (or, more pre
The answer to the question of why we use cephalo- cisely, of the upper lip as the representation of their
grams is probably that they enable the user to reach maxilla). Often, when the numbers gained by
a better diagnosis, which will in turn lead to more cephalometry do not correspond with clinical judge
comprehensive treatment of patients, with more ment, a correction of the original values according
stable results. In Western societies, comprehensive to the true vertical plane reveals much more mean
management includes aesthetics, and it is here that ingful results.
the true vertical correction of cephalometric mea A correction in relation to the true vertical has
surements becomes most valuable. For example, one absolutely mandatory requirement: every
cephalometric assessment may indicate that a cephalogram has to be taken in natural head
patient's maxilla is retruded while clinical evalua position. If this was not accomplished, extraoral
tion gives a different impression (3.5). How can this photographs that were taken in this surprisingly
happen? If, for instance, a patient has a skull con reproducible head posture (Moorrees and Kean,
figuration with a low-positioned sella, the reading 1958; Solow and Tallgren, 1971; Siersbaek-Nielsen
for the SNA angle will be small even if the maxilla and Solow, 1982; Cooke and Wei, 1988a; Cooke,
itself is correctly positioned in space. No patient is 1990) could be used for a subsequent reorientation
interested in the position of his sella, but almost_all of a cephalogram according to the true vertical (Jost-
B
K.Nadine KModine K,Nadine
* 2412/975 * 24.12.1975 * 24121975
= 290V985 = 29.01)985 = 29.0JM85
3.5 Natural head position and its in (B) The same tracing as in (A) with the (C) Obviously, in this patient the cant of
fluence on cephalometric analyses. (A) By Steiner analysis values. This data indicates, the anterior cranial base is remarkable (75,
simply looking at the tracing of this patient, for example, a retruded maxilla (SNA = standard value 85"). After correction in
one gets the impression of an almost 76) and mandible (SNB = 73 ) as well as a relation to the true vertical, the SNA now
normally positioned maxilla and mandible steep occlusal plane (24 , standard value measures 86°, SNB 83", and SN-OcP 14*,
with a more or less normal vertical facial 14°). which in our opinion is more in accordance
dimension. with the patient's actual appearance.
68
Brinkmann et al, 1989). Onlyjn natural head posi computer it corrects all linear measurements (e.g.
tion does a patient's a p p e t e n c e correspond to Wits appraisal, li-APog) to their original size. Thus,
reality, and the true vertical correction leads to more small errors due to image magnification - which will
reasonable cephalornctric readings (3.6). not affect angular measurements - can be compen
'Another important requirement is that all sated for. This is even more important for repetitive
cephalornctric X-rays should be taken with a mil assessments than for single ones, though it should
limeter scale (3,7). If this scale is read into the never be completely ignored.
3.6 Extraoral photographs of a patient w i t h her head slightly bent forward (A) and backward (C). Only with natural head position/
posture (B) does the profile assessment become definite.
3.7 If cephalograms are taken with a millimeter scale, as shown here,

even linear measurements f r o m different X-rays can be c o m p a r e d
because a correction t o the original (natural) size becomes feasible. In
o u r analysis, this correction is automatically accomplished by EDP
69
REFERENCE PLANES TRUE VERTICAL PLANE
The last problem that needs to be discussed before It was stated above that the problem of a constant
we will go into our specific analysis is which refer reference plane cannot be solved. This is not
ence plane or structure should a clinically mean absolutely correct. It can be solved if the true vejtical
ingful analysis be based on. The literature is full of plane is used. The true vertical plane is a constant
opposing statements. That is why the various ref and is perpendicular to the true horizontal, which
erence lines still compete with each other. It is also is a constant.. Some clinicians have acknowl
unlikely that this problem can be solved. One system edged this fact and developed a cephalornetric
is more or less as good or poor as any other, and assessment that is based on this reference plane
none is completely reliable because each is subject (Michiels and Tourne,J990; Viazis, 199J) (3.9).
ed to a large individual variability (3.8). What can However, the analysis of Michiels and Tourne only
be done to diminish this problem? The answer is to considers the spatial position of A, B, and Pog, and
choose measurements that are based on different ref furthermore it offers norms derived from only 13
erence planes; in this way it is hoped to compensate
females; on the other hand, the problem with the
for pronounced variations in one or the other ref
Viazis analysis is that it is based on the Bolton stan
erence lines, as if a measurement error is averaged.
dards, in which natural head position was never a
3.8 Variation of S N and FH in patients w i t h normal occlusions 3.9 Cephalornetric analysis by Viazis (1991) with ten variables.
f r o m t h e D o w n s series; s u p e r i m p o s i t i o n o n t h e palatal plane based on the t r u e vertical w i t h respect t o the t r u e horizontal. Red
(ANS-PNS). (From Thurow, 1970; reprinted with permission.) lines indicate skeletal measurements, blue lines dental variables,
and green lines the t w o soft tissue parameters. (From Viazis, 1991;
reprinted w i t h permission.)
70
serious consideration - in other words, the short SPECIFIC CONSIDERATIONS OF A

coming of the Viazis method is a lack of the equiv CEPHALOMETRIC ANALYSIS
alent norm data.
Almost the same is true for a summary five-factor The analysis we feel comfortable with at present is
cephalometric analysis described by Cooke and Wei divided into four fields or areas (3.11). These are:
[1988b) (3.10). The basis of this method is also • sagittal basal relationships;
natural head position but instead of being related to • vertical basal relationships;
the true vertical, it is related to the true horizontal • dentoalveolar relationships; and
plane (HOR). The angles NA and NB to HOR are • memos, i.e. important evaluations without proper
determined in the same way by Lundstrom and measurements.
Lundstrom (1989), as is the position of the chin and
the upper and lower lip as well as the incisor appear As stated above, in cephalometric analyses the cal
ance by Bass (1987|. Finally, the analysis of Spradley culated data is compared with other data. This data
etal(198l) is limited only to soft tissue points in the for comparison can be called by a number of names
lower facial third; somewhat similar is the cephalo — ideals, optimals, averages, means, norms, stan
metric evaluation which was suggested by Lund dards. The answer as to which is the best term could
strom and Cooke (1991). take much space but would probably still not satisfy
everybody, as it is almost a philosophical problem.
For the sake of simplicity, this data is here called
'standards', in the hope that this term is somewhat
non-committal and that it leaves room for individ
ual interpretation according to one's standpoint.
One could criticize us for relating a certain
variable to an author who did not describe it in the
first place. This may be correct, though in some
cases is it extremely difficult to identify the authen
tic originator. Therefore, we chose to ascribe every
assessment to the person with whom it is commonly
associated but who at the same time defined the
relevant reference points and planes most precisely
and gave the most thorough explanation of its
clinical importance.
A final criticism could be that readers do not
agree with some of the abbreviations selected
(SN-SGn instead of y-axis, etc.). We accept this crit
3.10 Five-factor summary analysts as described by C o o k e and icism, though we made these choices to give our
Wei (1988b). All measurements are based on the t r u e horizontal. analysis a certain homogeneity in its layout.
This plane was demonstrated t o be six times less variable than any
intracranial reference. A r e q u i r e m e n t f o r this is, however, that
every cephalogram be taken in natural head position. (From C o o k e
and Wei. 1988b; reprinted w i t h permission.)
71
Freie Universit&t Berlin

Fachbereich Zahn-, Mund- und Kieferheilkunde
Abt. fur Kieferorthopadie und Kinderzahnheilkunde
Cephalometric analysis
Name :
Birthday -
ID number : /
Variable: Stan TV 1.Ceph 2.Ceph 3.Ceph 4.Ceph Diff. Diff.

dard
FH-TV 92°
SN-TV 85° *
Sagittal basal relationships

SNA 82°
SNB 79° *
NPog-FH 83°
ANB 3°
WITS -1mm
NA-APog 3°
N'Pm'-DtUl 12°
vertical basal relationships

SN-SGn 66°
SN-NL 7°
SN-ML 30°
ArGoMe 124°
SGorNMe 68%
SN-OcP 14°
Dento-alveolar relationships
li-ML 96°
li-APog 2mm
li-ls 130°
Memo
1. Nasio labial angle 4. Morphology of the mandible
2. ls-lip line 5. Tonsilia pharyngea
3. Palatal spongeous bone 6. Tonsillae palatinae
3.1 I Form used for the analysis described in this chapter. The left upper corner shows personal data. The columns of the list contain
(left to right): the variable to be measured; the standard value for comparison; and the values that are corrected for the true vertical
(TV). These columns arc followed by those with the actual measurements ( I . Ceph, etc.) and the ones with the differences between any
two cephalograms (Diff)- The division of the form into four areas is clearly recognizable. (For further details, see text.)
72
ASSESSMENT OF SAGITTAL BASAL • actual reading < standard (eventually

RELATIONSHIPS (3.12) negative reading) - concave facial profile
(related to osseous structures), mesial relation
The following list consists of the parameters (abbre ship of mandible relative to maxilla.
viated) that are measured in the sagittal plane, the 7. N'Pm'—DtUl (Holdaway) — soft tissue convexi
persons to whom they are attributed, and the inter ty in relation to the projection of the most
pretation of the measurement results. The results are anterior part of the skull base onto the frontal
measured in millimeters for the Wits appraisal; the soft tissues and soft tissue promentale (g);
other results are angles, measured in degrees. All • actual reading > standard — convex (soft
values arc stated to one decimal place, which is tissue) facial profile, distal relationship of
almost more than adequate. Though every computer mandible relative to maxilla;
calculates easily up to eight digits, this is only fake • actual reading < standard (theoretically
precision because of the well-known limitations of negative reading) - concave (soft tissue) facial
the material (X-ray cephalograms) and the method profile (related to soft tissues), mesial relation
(evaluation of cephalograms) itself. ship of mandible relative to maxilla.
B. SNA (Steiner) - position of maxilla to skull First, it is obvious that this analysis is principally
base (a); based on very conventional measurements, which
• actual value < standard - retrognathic enhances communication. Further, it could be spec
maxilla; ulated that these measurements have some merits
• actual value > standard - prognathic maxilla. since they have been used for a long time.
1, SNB (Steiner) - position of mandible to skull Further, it is easy to reckon that the idea of dif
base (b); ferent reference planes was indeed realized: the
• actual value < standard - retrogenic Steiner angles are related to the SN plane, those of
mandible; Downs to the Frankfort Horizontal respectively to
• actual value > standard — progenic mandible. the anterior border of the skull base as well as to
3. NPog-FH (Downs) — position of mandible in each other (NA-APog), the Wits appraisal to the
relation to the Frankfort horizontal plane (c); occlusal plane, and the Holdaway soft tissue eval
• actual value < standard - retrogenic uation (like the NA-APog angle) to the extension of
mandible; the skull base onto the forehead, the chin, and the
• actual value > standard - progenic mandible. upper lip.
4. ANB (Steiner) - relation of maxilla and Such cross-evaluation with different reference
mandible to each other (d); planes is important; this can be demonstrated with
• actual value > standard - distal relation of two examples:
mandible relative to maxilla; 1. If one takes only the ANB angle to measure the
I • actual value < standard (eventually negative

reading) - mesial relation of mandible relative
to maxilla.
5. WITS (Jacobson) - relation of maxilla and
relative position of maxilla and mandible to each
other, one must realize that any different hori
zontal or vertical position of point N and the
location of the points A and B in the vertical
mandible to each other (e); plane will have an influence on the size of this
• actual reading > standard - distal relation of angle and not on the actual sagittal relation of the
mandible relative to maxilla; two jaws (Hussels and Nanda, 1984) (3.13). The
• actual reading < standard (eventually same holds true for a rotation of the occlusal
negative reading) - mesial relation of mandible plane: backward rotation of the occlusal plane
relative to maxilla. has a decreasing effect on the ANB angle,
6. NA-APog (Downs) - relation of maxilla and forward rotation has an increasing effect on the
mandible to each other as well as to the most ANB angle, though the sagittal basal relation
anterior part of the skull base (f); ships remain constant. Since the weakness of this
• actual reading > standard - convex facial measurement is known by many prudent ortho
profile (related to osseous structures), distal rela dontists, there have been attempts to individu
tionship of mandible relative to maxilla; alize the ANB angle, thus making it more
73
74
3.13 Schematic drawing of the effect on the A N B angle if a

certain parameter is changed while the others are held constant:
forward or backward rotation of the occlusal plane (A), vertical
difference in height of point A (B), vertical variation of point N (C),
and deviation in horizontal position of point N (D). (From Hussels
and Nanda,l984; reprinted with permission.)
* •
N N'
Variable Standard Patient I Patient II Patient III Patient IV
Angle Clas I HI ill 1
ANB angle (°) 7.8 1.0 0.9 -0.5
Wits appraisal (mm) 1.4 -8.1 -6.5 2.4
SN-ML 0 44.5 42.3 41.0 25.5
|SG:NMe(%) 57.1 62.6 58.7 70.4
' NL-ML 0 24.0 34.0 31.0 31.8 24.8
SN-OcP (°) 13.5 23.9 22.4 22.8 9.4

i
Table 3.2 List of four patients who in a study on this subject were found to have the largest ANB-Wits appraisal differences (with adult
unisex standards for comparison). It becomes obvious that these patients had either a Class III malocclusion (patients II and III) or
demonstrated a pronounced vertical deviation (being excessive in patients I to III and deficient in patient IV). Patient I was. despite her
nije ANB angle, considered Class I (with an open bite). In general, the Wits appraisal agreed more with the clinical classification.
75
independent of variations t h a t are n o t directly severe vertical discrepancies (Table 3.2). There
connected to the sagittal jaw relationship fore, it is reasonable to assess the sagittal jaw base
(Kirchner and Williams, 1993). Panagiotidis and relationship with measurements that are based on
Witt (1977) give an e x a m p l e of this a p p r o a c h . different reference planes. Further, it is important
They recommend t h e calculation of the repre to look with special care at those patients where
sentative ANB angle hy the formula -35.16 + 0.4 there are contradictory results in the anteropos-
(SNA) + 0.2 ( M L - S N ) . T h e only problem with terior jaw relation.
this procedure is that it is not very easy to use and Above all, it is important to make the final decision
it is therefore n o t likely to be regularly used by a b o u t the existing sagittal basal problem after a
clinicians. t h o r o u g h clinical e x a m i n a t i o n . This advice is in
2 . If, for instance, t h e ANB angle a n d the Wits accordance with that of Bittner and Pancherz
appraisal both measured the true relative sagittal (1990), w h o stated that 'sagittal and vertical dental
relationship of the mandible t o the maxilla, their and skeletal intermaxillary malrelationships (as
correlation coefficient should be 1.0. In their detected on cephalograms) were only partly reflect
study, Miethke and Heyn (1987) found that this ed in the face' (3.14). However, facial appearance is
correlation in fact varies between 0.24 and 0.85 w h a t most patients are really interested in.
with an average of 0.8. This means t h a t after a The angle of facial convexity and the soft tissue
simple statistical rule of t h u m b barely t w o thirds profile evaluation d o not seem very meaningful to
of the variations are explained by the t w o vari us any m o r e . T h e N ' P m ' - D t U l angle is recorded
ables; the rest is due to chance. In the same study, mainly so t h a t o u r analysis c o n t a i n s at least one
it also became obvious that these t w o measure measurement related to soft tissue. But both mea
ments were most contradictory in patients with surements are, according to o u r very personal ex
severe skeletal problems. This was mainly due to perience, on the verge of being omitted.
S A G I T T A L J A W B A S E R E L A T I O N S H I P
N o . % ( A N B - A n g l a |
ao
Validity
ED v * « - v »^l
6 0 _
E3 high
«»o -
2 0 _
Clas
11
3.14 In this study by Bittner and Pancherz (1990), the validity of the sagittal basal relationship was assessed when seven investigators
inspected photographs of 172 children. It becomes obvious that only patients w i t h a Class II anomaly are easily detected. The failure race
in patients with a Class I o r a Class III malocclusion is high. (From Bittner and Pancherz, 1990; reprinted w i t h permission.)
76
ASSESSMENT OF VERTICAL BASAL • actual value > standard - increased (lower

RELATIONSHIPS (3.15) anterior) vertical facial height.
12. SGo: NMe (Jarabak) - ratio of posterior to
The vertical evaluation consists of the following anterior facial height (m:m');
measurements, again — as above - with its originator • actual value < standard - increased total
Jmd its interpretation; the measurements are anterior vertical facial height;
percentages for the faciaJ height index; all the others • actual value > standard - decreased total
are angles given in degrees: anterior vertical facial configuration.
8. SN-SGn (Brodie) - chin position in relation to 13. SN—OcP (Steiner) - cant of occlusal plane to
skull base (h); skull base (n);
• actual value < standard - decreased vertical • actual value < standard - decreased vertical
facial height; dentoalveolar dimension;
• actual value > standard - increased vertical • actual value > standard - increased vertical
facial height. dentoalveolar dimension.
. SN-NL (Hasund et al) - cant of maxilla to skull
base (i); The last measurement is not strictly a skeletal mea
• actual value < standard - decreased upper surement. It is related to occlusion and would there
facial height; fore be better listed as a dentoalveolar assessment.
• actual value > standard - increased upper However, as aU the other tooth-reVated measure
facial height. ments are purely sagittal, it seemed more logical to
10. SN-ML (Hasund et al) - cant of lower border add it at the very end of the vertical parameters.
of mandible to skull base (k); Again it can be noted that the different measure
• actual value < standard - decreased vertical ments depend on various references. Four of them
facial height; are based on the SN plane (SN-SGn, S N - N L ,
• actual value > standard — increased vertical SN-ML, and SN-OcP), whereas the other two have
facial height. a relation in itself- the gonial angle in the mandible,
11. Ar-Go-Me (Bjork) - angle between ramus and the facial ratio in the general vertical structure of the
corpus mandibulae (1); face.
• actual value < standard - decreased (lower We have often found- and probably this experi
anterior) vertical facial height; ence is shared by many clinicians - that one specific
3.15 All vertical basal and dentoalveo

lar parameters measured. For abbrevia
tions the readers are r e f e r r e d t o the
text.
77
assessment of a patient will indicate deficient vertical Basically it can be solved by not paying too much
skull architecture while another assessment will attention to any particular measurement, but instead
point in the opposite direction. For instance, Duter- finding out about the general trend of the vertical
loo et al (1985) make a distinction between skulls skull structure. This can be accomplished in differ
with a small and a large divergency (3.16). However, ent ways. The simpliest is to overview all numeri
the most hypodivergent skull (Skull 1) demonstrat cal values and re-evaluate them as a whole. Another
ed a larger angle SBa-NL than the most hyperdi- way is to have a graphical presentation as in the
vergent skull (Skull 2). What can be a solution to polygon devised by Vorhies and Adams (1951). One
this dilemma? critical look at this will show whether the vertical
3.16 Though in an investigation by D u t e r l o o et al (1985), Skull I

(A) was characterized as having a relatively small divergency, it
demonstrated a larger SBa-NL angle than Skull 2 (B), which was
considered t o have a relatively large divergency. (From Duterloo et
al, 1985; reprinted w i t h permission.)
78
values tend to be more on one 'shoulder1 or the other. most objective method of describing the overall sev
The best approach is probably to establish an overall erity of a patient's vertical problem. The only dis
vertical index. The original idea for such a summary advantage of this procedure is that it takes more time
assessment seems to go back to Schopf (1982) (3.17) and effort than an average evaluation and, therefore,
and was further developed by us (Heyn, 1986). As will probably not be accepted for regular use by the
seen in Table 3.3, a particular vertical measurement majority of clinical orthodontists. An evaluation
is credited with a certain value, which can be positive index could also advantageously be developed for
or negative depending which vertical extreme it is the assessment of the sagittal basal relationship in
tending towards. The resulting value may well be the cephalograms.
3.17 Graph (redrawn) developed by

Schopf (1982) to assess the general ver
tical facial configuration. In this particular
patient, four out of six parameters are in
dicating an above-average facial structure.
le 3.3 Evaluation list in which every measurement is credited with a certain number (rating) to assess the overall vertical basal
duration of an individual patient. Plus and minus values will either balance or enforce each other. This approach dates back to 1986, a
wat which we still used the sum angle (NSBaGoMe) of Bjork, which we have subsequently stopped using.
79
Orthodontic Cepkalometry
GROWTH PREDICTIONS called a prediction, though a more apt term might

be 'guessing'. This is especially valid if such a
Up to here, the term 'growth' has not been used in forecast is founded just on clinical experience.
this representation.The reason is twofold: The outcome may be more reliable if it results
1. Often cephalograms are taken in adults where the from a very large computer data base, though
term in its original meaning cannot be applied, even in such cases doubts are advisable
even though up-to-date information confirms (Greenbcrg and Johnston, 1975; Witt and Koran,
that growth almost never ceases completely, as 1982). In a revealing study, Baumrind et al (1984)
already stated above. demonstrated that vertical growth prediction was
2. It seems very dubious to make a statement about not better than chance even when performed by
growth, which is a four-dimensional process presumably very experienced clinicians with a
(sagittal-vertical-transverse change over time) on mean duration in clinical practice of 28 years.
the basis of a two-dimensional image, especially A growth prediction with a certain clinical impact
since it excludes time, the most important para is feasible, however, when two cephalograms with
meter. To make a statement about the further a due time interval are taken from the same patient.
development of an anatomical entity is often Then the development in sagittal and vertical dimen-
3.18 Superimposition on the areas of the cranial floor, which are 3.19 In this eight-year-old patient, the occipital part of the head
marked by red lines, according to Steuer (1972) and Riedel (1972). cannot be seen, so no statement about her cephalic type is
In this girl, the maxilla between the age 12 and 13 has grown possible. Even if her nose tip were right next to the right margin o(
slightly mesial and remarkably caudal. Since the mandible is the film, it would still be doubtful if the patient's whole head would
influenced by the maxillary growth and translation as well as by its have been imaged. What is described here is even truer for adults.
dentoalveolar changes, no information can be gained directly about
the predominant mandibular growth direction. Overall, this patient
obviously shows a rather vertical growth pattern. The vertical lines
indicated by the arrow do not belong to the cranial base but are
the wings of the sphenoid bone. Because of their distinct vertical
i
course, they definitely help to orientate the two tracing on each

other.
80
sion can be evaluated either by comparing respec fulness. However, our favourite vertical assessments
tive (numerical) values or graphically by superim- are the facial ratio and the gonial angle. Both seem
position (3.18). Again, some scepticism is to have the highest practical importance. They
warranted, since there is no guarantee that a specific appear to err less than other values, and a possible
growth direction is valid during the whole devel explanation is:
opmental process. The work of Linder-Aronson et • the facial ratio depends not on three reference
Jal (1986) in particular has proved that in some points but on four. It is possible that the inclusion
patients vertical growth can change - either diminish of one more anatomical structure lessens the like
or increase. Nonetheless, most patients follow their lihood of a deviation that is derived by chance.
original growth path. Furthermore, the linear measurements of the pos
However, the only absolutely correct growth terior and the anterior facial height actually take
evaluation remains a retrospective one. Because of place in the vertical plane.
the above-mentioned possible complications, we • the gonial angle is related to the mandible, a
have decided not to use the term 'growth'. Instead, structure that contributes remarkably to the
| we use terms such as face or skull structure or con vertical growth process. An anatomical compo
figuration, because these descriptions are more nent such as this is a more sensible parameter
neutral and thus more relevant. than structures that depend on the anterior
For a similar reason we stay away from the cranial base (SN), which is located far away from
expressions brachycephalic and dolichocephalic. the (lower) visceral skull. This is in keeping with
Originally these anthropological terms included the Ricketts (1972), who recommends reliance on the
(overall skull depth (anteroposterior dimension), mandibular arc (angle) (3.20). The only objection
.which is almost never imaged in an average cephalo- to this angle is that point Xi is much more diffi
jgram (3.19). Furthermore, a brachycephalic or cult to determine (Miethke, 1989).
(dolichocephalic characterization has to include an
(evaluation of skull width (frontal plane), which is We are often asked why the Bjork sum angle is not
[impossible to deduce from a standard cephalomet- used in our analysis. The answer is quite simple: the
ric X-rav. sum angle equals the angle SN-ML adding 360°
As noted above, some of the sagittal basal rela (Reck and Miethke, 1991) (3.21). Thus, by mea
tionships have lost for us some of their previous use suring SN-ML, we indirectly included the Bjork
sum angle in our analysis.
s ^
^?o[y — ^ H- »
<^x^\ *ViV-
" ^ ^ n\ t t
Go ^tt, ) II 0°
Me
3.20 The mandibular arc (angle) is based 3.21 Schematic drawing of the geometric relation between the angle SN-ML and the
on the reference points DC, Po (PM), and sum angle of Bjork (Jarabak). (For further details, see Reck and Miethke, 1991.)
I Xi. The accuracy and reproducibility of the
bst point in particular is very low. (Redrawn
(from Ricketts, 1972.)
81
ASSESSMENT OF DENTOALVEOLAR
RELATIONSHIPS (see 3.15) T h e first aspect that becomes o b v i o u s is that this
part of o u r analysis is extremely short. However,
O u r cephalometric evaluation of the dentition there is nothing w r o n g with this - if shortness were
involves only the following three measurements an indication of concentration, it would be advan
(abbreviations, originators, and interpretations as tageous. Tweed's original analysis (1969) consisted
above): also of only three measurements (3.22). Was it there
14. li—Ml, (Downs) - axial inclination of lower fore worse than o t h e r analyses? Were treatments
incisors in relation to mandibular plane (o); based on this analysis inferior or less stable - if the
• actual value < standard - retroinclination of analysis was used with a critical mind? We feel that
incisors in the mandible; the measurements listed above are, in general, suf
• actual value > s t a n d a r d - proclination of ficient. Again - as mentioned previously - there is
incisors in the mandible. ample space at the end of this part of o u r analysis
15. l i - A P o g ( M c N a m a r a ) - position of lower w h e r e further parameters could be added if felt
incisors relative to anterior border of maxilla appropriate.
and mandible (p); Also it will be noticed that the evaluation of the
• actual value < s t a n d a r d - retroposition of incisors in the mandible is in the centre of attention.
mandibular incisors; This seems to be reasonable, since modern ortho
• actual value > s t a n d a r d - anteroposition of dontics focuses on this criterion (Miethke and
mandibular incisors. Behm-Menthel, 1988).
16. l i - l s (Downs) - axial inclination of lower and Again, there a r e two reference planes that are
upper incisors to each other (q); independent of each other:
• actual value < standard - protruded position • the mandibular plane and
of upper and lower incisors to each other; • the plane that describes the anterior border of
• actual value > standard - retruded position of both jaws (A-Pog plane).
upper and lower incisors to each other.
3.22 The Tweed analysis originally inclu

ded only these three measurements. It is
o b v i o u s l y c e n t r e d a r o u n d t w o highly
c r i t i c a l p a r a m e t e r s : the p o s i t i o n of the
mandibular incisors (over basal bone), and
t h e angle F M A , w h i c h r e p r e s e n t s the
(anterior) vertical dimension of the maxilla
and the m a n d i b l e . ( F r o m T w e e d , 1969;
reprinted with permission.)
82
Additionally the angular and the linear measure panoramic X-ray can easily fulfil the same purpose,
ment are thought to 'control' one another. as one can see the posterior border of the mandibu-
The inclination of the maxillary incisors can lar and maxillary dentition (ramus ascendens and
easily be assessed indirectly through the interincisal maxillary tuberosity) as well as one can on a head-
angle, and their position can be assessed indirectly plate (3.24).
through the overjet (3.23). Finally, one may criticize on the basis that all den-
The measurements consider only anterior and not toalveolar assessments are purely sagittal. However,
sterior teeth because we feel that the anterior this is not really true, since the cant of the occlusal
ent of the dentition is much more critical as far plane (to SN) is giving us a sufficient indication of
ssuccess and stability of orthodontic treatment is the overall situation of the teeth and the alveolar
concerned. However, there is nothing wrong with processes in the vertical plane.
an evaluation of the molar position. Besides, any
3.23 In this patient with a Class II Division 2 malocclusion, the

M—ML angle amounts t o 91.9" (age- and sex-corrected standard
92.0"). The interincisal angle totals 159.8" (compared t o standard
130.0"); t h e r e is no o v e r j e t . C o n s e q u e n t l y , the p o s i t i o n and
inclination of the maxillary incisors can be indirectly assessed as
palatally inclined and located.
53 B
3.24 Orthopantomogram of a 15-year-old female. There seems

j to be sufficient space according t o the patient's age f o r the third
! molars to erupt later (A). This impression is confirmed on clinical
examination (B). There is extra space distal t o the second molars,
! whidi is seen better on the right than o n the left side (owing t o
nrror position).
83
NON-METRIC ASSESSMENTS OF THE 17. Nasiolabial angle - angle between columella

SKULL A N D SOME SURROUNDING and philtrum of upper lip.
ANATOMICAL UNITS
Ideally this angle should be 90° to 100° (Brown and
At this point the metric evaluation of cephalograms McDowell, 1951). This angle is age-dependent; it is
in our analysis is concluded. Nevertheless, it would small in very young children (87.5° in newborns)
not be appropriately complete without the follow (3.25) and increases remarkably in teenagers
ing observations. They are listed under the headline (111.5°), getting only slightly bigger in twenties
'Memo', which implies that they should not be over (112° on the average) (Miethke, 198Q) (3.26). This
looked even if they are not measured in degrees and means that there is a difference between the average
millimetres or calculated in percentages. So the of our population and the ideal. Expert texts
topics (17-22) listed below have to be checked off continue to explain that even a nasiolabial angle of
either taking a mental note or adding a free formu 120° can be acceptable; for instance, Brown and
lated text: McDowell (1951) state that this can look 4piquante'
in some faces.
B
3.25 Average (B) as well as minimum (A) and maximum (C) nasiolabial angle in newborns.
A B C
3.26 Average (B) as well as minimum (A) and maximum (C) nasiolabial angle in adults (dental students).
84
Overall, the message is that if this angle is initially than average skull configuration, and the higher
small, the facial balance could be improved by ratio (three quarters) in patients with a more pro
choosing a treatment approach that would increase nounced decrease in facial height. We do this
it (Lo and Hunter, 1982). On the other hand, if the because lip length is almost impossible to alter, and
nasiolabial angle is large in the beginning, treatment a necessary vertical change in the incisor position is
should not aim to increase it. often compromising the patient's appearance.
Ir is beyond the scope of this text to go into For example, patients with an excessive vertical
details about whether extractions of maxillary teeth skull structure often have a very minor overbite,
I
have an influence on this angle. There are doubts_as sometimes a manifestly open bite. At the same time
to whether the angle can be influenced by orthp- their upper lips (if not both lips) are short, so that
clontic means atone (Paquette et al, 1992; "Young these patients tend to have a 'gummy' smile (3.28).
and Smith J_993) but there can be no doubt that A relative intrusion of the upper incisors, which
orthognathic surgery (combined with orthodontic would bring them into a favourable alignment with
treatment) is able to alter it. the upper lip, would worsen the overbite situation.
Finally, age (see above) and also a patient's sex The only solution in these cases is to intrude these
(females often prefer to have fuller lips than males) teeth just as much as necessary (the two thirds goal)
and establish a good, functioning overbite (with an
should never be overlooked when a particular nasi
incisor guidance) by rotating the whole lower dental
olabial angle is considered as a support for a specific
arch counterclockwise, and t o supplement this with
therapeutic approach.
some extrusion of the anterior mandibular teeth.
18. Is - lip line - relation of the most caudal part of Any orthodontist should realize at this point this
the upper lip to the labial surface of the maxil true dilemma. Let us describe it with another
lary (central) incisors. example. A patient whose skull structure is lower
than average is prone to have a deep bite and rather
Probably it is a somewhat fruitless discussion long lips. The first treatment option, therefore, is to
whether the relaxed upper lip should cover three extrude the posterior teeth, thus indirectly opening
quarters or two thirds of the upper anteriors or leave the bite and 'shortening* the lips. Many eminent
about a 2-mm 'show', as stated by different ortho orthodontists object strongly to this approach
dontists (Arnett and Bergman^JSSS) (3.27). Our because they claim that such an extrusion is not
point of view is that it should be within this range. feasible in that it is very likely to relapse because the
For practical purposes, we take the lower value (two facial musculature works against any vertical
thirds) into consideration in patients with a higher increase, whether in growing children or in adults.
I
3.27 Attractive tooth/lip line relationship with the lips slightly
apart.
$5
Therefore, they demand to solve the existing deep trading good morphology against a good smile
bite problem by an intrusion of the incisors. But do (3.29) because, if the anterior teeth are hidden behind
they consider what happens to the tooth-lipline rela- the lips, a patient gets the 'disastrous' appearance of
tionship at the same time? Acting this way means an old person (Perkins and Stale_y,J_993).
3.28 (A) Eight-year-old patient w i t h a s h o r t upper lip and a eruption of posterior teeth, intrude her upper anterior teeth in
considerable 'gummy' smile. (B) A l t h o u g h , this patient d e m o n - harmony with her lip length, and establish sufficient overbite by a
strates hardly any overbite, it w o u l d be, aesthetically, completely counterclockwise rotation of her mandible supplemented possibly
unacceptable t o deepen her bite by (maxillary) incisor extrusion. with minor extrusion of her lower incisors.
Instead, every e f f o r t should be made t o c o n t r o l the patient's
3.29 Even when this patient gives a full smile, very little of his r a t h e r long lips, giving him an unpleasing, almost senile look.
maxillary anterior teeth shows (A). A t the same time this patient Instead, everything should be attempted t o open his deep bite
exhibits a deep bite which should not be corrected by intrusion of i n d i r e c t l y by an increase in v e r t i c a l d i m e n s i o n (extrusion of
the incisors (B). This would make his teeth disappear behind his posterior teeth).
86
The author of this text does not have the final tively, the ultrasonographycally measured mor
solution to this problem. However, if one believes it phology of the masseter muscle and a specific
is possible to influence 'growth 1 , would it then be vertical skull configuration (Ruf, 1993).
completely absurd to include muscles as well as Overall, the relationship of the (maxillary) incisors
bone? If we take adaptation into account could this to the (upper) lipline should be evaluated, even if the
not even occur to a certain degree in adult patients? clinical consequences are not easy to solve.
How do many experienced maxillofacial surgeons
approach the problem of a vertical facial deficien- 19. Palatal spongeous bone - cancellous bone
I a and a deep bite? Do they not also increase the behind the maxillary incisors.
posterior vertical dimension? Even if, in all these cir
cumstances, some relapse evolves, at least this could Many orthodontists agree that teeth should only be
be considered as a compromise between the optimal moved through spongeous bone. Many feel that if
and the possible. Furthermore, it should be pointed teeth contact cortical bone either root resorption or
t out that a recent doctoral thesis has failed to prove

[adistinct correlation between EMG activity respec
a perforation of the bony cortex (or both) may be
the result (Ten Hoeve and Mulie, 1976) (3.30).
3.30 Example t o demonstrate the rela

t i o n between the a m o u n t o f palatal b o n e
and possible r o o t resorption. (A) Cephalo-
g r a m of a p a t i e n t in w h o m maximum
retraction of the incisors was planned. The
incisors are located directly anterior t o the
palatal cortical plate. (B) A superimposition
o n the maxilla shows that the front teeth
were distalized w i t h o u t any intrusion. The
tracing f r o m the treatment result (broken
lines) implies that the incisors are almost
w i t h i n t h e c o r t i c a l b o n e . ( C ) Periapical
radiographs of (right) maxillary incisors at
the beginning of treatment. (D) The same
t e e t h as in (C) at the end of r e t r a c t i o n
therapy. Probably because these teeth have
contacted the c o r t e x o f the hard palate,
some remarkable apical r o o t r e s o r p t i o n
has occurred.
(Courtesy of D r L Alverado de Scholz.)
87
Therefore, the amount of spongeous bone that is mum distalization of the anterior dental segment is
palatal to the maxillary incisors determines the required (so-called maximum anchorage cases) but
amount they can be ideally retracted. Admittedly in whom the amount of spongeous bone behind the
this information can also be gained by a model incisors is not adequate? John H. Hickham taught
analysis, but only partially. The slope of the anterior us to answer the previous question with these
part of the palate is often simply a reflection of the words: 'You have to get them up to get them back'
incisor inclination, although the amount of (Hickham, 1978). Every intrusion brings the
spongeous bone that is palatal to the incisors varies incisors into a position where more spongeous bone
from patient to patient, even among patients with for tooth movements is available (3.32).
an identical incisor position. Therefore, varying Even if there is only limited scientific proof, it
amounts of complication-free retraction are feasible seems that one contributory factor for root resorp-
(3.31). What about those patients in whom maxi- tion is too intimate a contact between the (palatal)
E, Bettina
* 26.02MB
— WJ2.1985
- 1109.1986
2-3
3.31 Midsagittal sections through models of different patients.

Although the incisor inclination does not vary remarkably, there
are obvious differences in the spaces behind their r o o t s . I t is
impossible t o state which of these spaces are occupied by the
gingival tissue o r h o w thick the palatal c o r t i c a l plate is in any
individual patient. Even so, this may prove that, w i t h the same
t o o t h position, the slope of the palate varies, as does the amount
of spongeous bone behind the maxillary anterior teeth.
3.32 Adult patient with maximum anchorage requirements at the

beginning of treatment. Although some mesial molar movement
has o c c u r r e d , the incisors have obviously been retracted (and
uprighted). The distalization did not result in any r o o t resorption,
though the cortex of the palate was adjacent t o the incisor roots.
W e believe that this uneventful retrusion was only feasible because
it was accompanied by an intrusive component.
SK
cortex and the roots of the respective teeth demonstrate certain peculiarities in the morphology
(Wehrbein et al, 1990). Therefore, it should be of their mandibles, as well as their whole skulls
decided if a maximum retrusion of the incisors can (3.33). Since these peculiarities remain after puberty,
be attempted, and if so, how it can best be accom they can be distinguished in adults as well as children.
plished. The cephalogram will give valuable hints Why worry about the vertical dimension in
for the solution of this critical clinical problem. adults, where growth will not change it any more?
This concern seems indicated since any therapy with
20. Morphology of the mandible - typical structural extrusive components will have much more exten
features of the lower jaw. sive consequences in patients with vertical excess.
Their bite opens sometimes very fast, followed by a
Through his classical implant studies, Bjork (1969) tongue position between upper and lower incisors
found that patients with different vertical growth which again has a negative effect on the overbite
3.33 The morphological characteristics of

the mandible that are supposed to indicate
p r e d o m i n a n t g r o w t h d i r e c t i o n (skull
c o n f i g u r a t i o n ) . (A) The shape of the
condylar process and the course of the
mandibular canal are rated with a number
between +3 or -3 depending on which
e x t r e m e they are tending t o . Left
•3 ♦2 ♦1 -1 -3 horizontal, right vertical g r o w t h (skull
configuration), (B) The arrows point t o
areas of the mandible with pronounced
bone apposition (+) or resorption (-), and
respective thickness of bone tissue. Left
horizontal, right vertical g r o w t h (skull
configuration). (After Segner and Hasund,
1991; reprinted with permission.)
89
(3.34). In short, this can easily become the begin • allergic rhinitis/nasal hyperactivity; and
ning of a vicious circle. T h a t is why attention has to • chronic rhinosinusitis.
be paid to the vertical skull configuration, even in
adults. T h e o r d e r of frequency varies depending on envi
Bjork's structural analysis can be used to evaluate r o n m e n t a l and other general conditions, and it
a patient's c e p h a l o g r a m and it is just a n o t h e r varies according to a patient's age; however, one or
attempt to make double sure and triple safe not to more of these four aspects is usually the cause.
miss a patient's vertical problem. Under this premise, it makes sense to evaluate the
size and formation of the tonsilla pharyngea, which
2 1 . Tonsilla pharyngea - size of pharyngeal can be well distinguished on a lateral cephalogram
adenoids relative to upper airway diameter. (3.35). It is not safe to assume, however, that there
is an airflow inhibition if the area between the
Only few o r t h o d o n t i s t s and scientists d o u b t t h a t a d e n o i d s and the soft palate is n a r r o w e d . This is
there is a cause-effect relationship between mouth because t h a t the cephalogram provides a two-
breathing and the vertical development of the skull, dimensional view of a three-dimensional anatomi
the face and the dentition (CKRyan et al, 1982; Vig, cal structure, in which only these surfaces that are
1991), w h e r e a s the majority of clinicians a n d tangentially hit by the X-rays are imaged - mostly
researchers believe t h a t they have good proof that those structures in the midsagittal plane. This means
this relationship exists (for e x a m p l e , Linder- t h a t the adenoid masses to both sides of the
A r o n s o n , 1970; Woodside et al, 1991). With this midplane can be much smaller than they appear on
relationship in mind, it is w o r t h remembering that a cephalogram, and thus they can compensate for
the four most important reasons for inhibited nasal apparent constriction. This is one reason why we do
breathing are: not measure any distance in this area numerically,
• enlarged pharyngeal (and eventually palatal) as other analyses recommend. Nevertheless, we feel
tonsiLs; that this assessment has the same importance to us
• deviations of the nasal septum; as if we evaluated it quantitatively.
3.34 A 32-year-old patient w i t h m i n o r o v e r b i t e w h o seeked

o r t h o d o n t i c t r e a t m e n t f o r cross-bite c o r r e c t i o n of upper left
lateral incisor (A). She presented w i t h an additional cross-bite of
the right first molars and a moderate curve of Spee (B). Mainly
because of levelling with extrusive mechanics and also because o1
some c o r r e c t i o n of the lateral cross-bite, the anterior overbite
changed t o an open bite. Though not completely contraindicated
(because the upper left lateral incisor has t o be moved labially) it
will be difficult t o close the bite again. It is easy t o imagine that
now a tongue interposition exists (C).
90
Any patient in whom an obstruction of the upper c e p h a l o g r a m s and a reasonable referral policy
nasal airways is suspected (whether from clinical should be practised.
inspection or radiography) should be referred to an
ENT specialist w h o can ascertain w h e t h e r or not 2 2 . Tonsillae palatinae - estimated size of palatal
such an obstruction is present. tonsils.
It is often best to approach E N T colleagues with
questions that require exact answers a b o u t the Finally, the palatal tonsils should b e evaluated.
existing airflow condition (Jonas and M a n n , 1988; Although the palatal tonsils seldom obstruct the
Zimmerand Miethke, 1989). This approach almost airway (the main exception being the clinical con
always results in a written reply that satisfies us and dition described as 'kissing tonsils', in which grossly
that can be kept in the patient's records. enlarged tonsils almost meet in the middle of the
Even if the influence of adenoids on the breath oropharynx), they can, even under less extreme cir
ing mode is not yet absolutely clarified and even if cumstances, inhibit breathing during sleep (sleep
the definition of mouth a n d nasal breathing may be a p n o e a ) (3.36). M u c h has been w r i t t e n recently
very difficult to accomplish with scientific precision, a b o u t this condition, and it is a problem that can
; we feel it is our duty as dental surgeons t o follow all have serious consequences to health (Knobber and
traces which may be unfavourable for the develop Rose, 1985; Potsic and Wetmore, 1990).
ment of our patients. Even if inhibited nasal breath Nocturnal breathing obstruction is one reason for
ing does not influence the n o r m a l g r o w t h of the inspecting the tonsils on c e p h a l o g r a m s . A n o t h e r
orofacial structures, we still strongly believe that it reason is that hypcrplastic lymphatic tissue in this
has an impact on the general development of a child. area occupies space that actually should be filled by
Therefore, adenoid size should be checked in the posterior part of the tongue. This can lead to an
3.36 Enlarged tonsillae palatinae with typical signs of (chronic)

inflammation in an 11-year-old boy. Although these tonsils do not
inhibit his breathing during the day. it was considered that they
were the cause of his sleep apnoea.
JJ5 Eight-year-old patient w i t h obviously enlarged adenoids

(verified by ENT specialist). Although her lips are closed o n this
rephalogram, they are m o r e o f t e n apart. T h e r e f o r e , she was
considered a mouthbreather. H e r vertical skull configuration is
somewhat excessive (e.g. large gonial angle), but her overbite is
Kill sufficient.
91
altered tongue position and function. A more wall. McNamara states that a distance up to 14 mm
forward position or an anterior function of the is normal, but that anything above this might be the
tongue is often related to the development or pro result of oversized tonsils if the measurement has not
gression of a Class III malocclusion or an open bite been falsified by tongue movements (as happens, for
(Fischer and Miethke, 1988) (3.37). Studies have instance, during swallowing).
suggested that this deviation from normal is one This is not the only problem in assessing the size
factor that causes relapse after a correction of the of the tonsils. Another is that the palatal tonsils can
anomalies mentioned above (Grunert and Krenkel, almost never be seen directly on a cephalogram
1991), although no sound scientific proof is yet because of their indistinct structure. Instead of mea
available. suring the tonsillae palatinae, cephalograms in fact
The idea of assessing the size of the palatal tonsils measure the amount that the radix of the tongue is
is not new. Several clinicians and researchers have displaced from where it is believed it should be.
suggested a great number of measurements for this Because of these problems, it is probably more rea
purpose (for example Bergland, 1963; Linder- sonable to leave the evaluation of tonsil size to a
Aronson, 1970). One of the latest, best-known common sense clinical guess.
approaches is that suggested by McNamara and Therefore, even if the size of the tonsillae palati
Brudon (1993). It is advocated to measure the nae is stated in the cephalogram report, it is worth
distance between the intersection of the inferior correlating this result with the clinical evaluation,
border of the mandible with the dorsum of the especially in patients who have sleeping disorders
tongue to the closest point of the posterior pharynx and a tendency towards a Class III or an open bite.
3.37 Eight-year-old boy with a Class III and an open bite; ANB =
2,5", Wits appraisal = -5 mm. The typically enlarged tonsils are
depicted with a broken line. The distance between the dorsal
pharynx wall and the intersection of the tongue with the lower
border of the mandible amounts to 16 mm.
92
GRAPHICAL REPRESENTATION OF or in patients who undergo orrhognathic surgery

NUMERICAL FINDINGS IN therapy as well as orthodontic treatment. In the
CEPHALOMETRY first case, however, we can practically never be
sure how much of the skeletal change should be
The idea of presenting the numerical findings of a attributed to our treatment and how much t o
cephalometric analysis in a graphical formula has independent growth.
long been advocated (Vorhies and Adams, 1951),
We feel rhat such a graphical representation has A graphical representation is shown in 3.38. The
several advantages: graph is automatically plotted as soon as the numer
1. Intellectual abilities of individual practitioners are ical data is calculated. For repeated analyses the
different. Some prefer a more abstract and theo same document can be fed into the plotter again.
retical approach, while others prefer a more Critical readers now may ask the questions: Why
concrete, practical approach. Some orthodontists so much fuss? What is characteristic of the 'wiggle-
can be fully informed by looking at the measure gram' you have developed? At the beginning of the
ments that result from their analysis, whereas form, the name, date of birth, and code number of
others find it quicker and easier when the mea the patient is found. The graph, by means of spaces,
surements are expressed graphically. reflects the separation of the different fields
Despite the fact that some orthodontists may (sagittal-basal, vertical—basal, and dentoalveolar
prefer a graphical presentation of cephalometric relationships). The internal structure of the graph is
data, every orthodontist is able to follow a such that the spaces between all values of each mea
numerical analysis. This is not the case, however, surement are very specific. Thus it is guaranteed in
with experts from other medical specialities, and an adult patient (15 years and over) that:
their understanding of the problems revealed by • all standards will form a straight vertical line in
a cephalometric analysis is remarkably improved the centre of the representation; and
by a graphical representation. • the double plus and minus standard deviation is
I. This aspect becomes even more important when represented by two dotted straight lines on either
lay persons - patients and their parents, relatives, side of the standard.
and friends - are confronted with a cephalomet
ric analysis. A numerical analysis is almost never The standard value is always marked individually
comprehensible to people who have not been by the plotter with a small black cross. This value
medically trained. Even if they cannot fully depends on the patient's age and sex. If the patient
understand a graphic representation of the same is not yet fully grown (as conventionally defined)
analysis, they will certainly be able to get a better this cross will be (slightly) off centre.
understanding of the situation. This better under The lines that represent the twofold standard
standing will produce a patient or parent who is deviation are not always absolutely straight vertical
much more our ally than enemy. Some prerequi lines, as this is also age- and sex-dependent.
sites must be fulfilled to accomplish this better However, their deviation from ideal straight lines
understanding, and these are described at the end is usually hard to reckon. In any case, the ±2
of this list. standard deviation field includes all cephalometric
■(.Possibly the most important reason to have access values that can be defined as physiological (i.e.
i to a graphical representation of the cephalomet- normal).
Iricanalysis is that, by studying it carefully, one If the standard is in the middle and the two outer
becomes more self-critical and modest. This is lines mark the normal variation the lay person better
true under the condition that the graph of our understands how far away the patient in question is
. analysis shows the results of repeated cephalo- from the ideal, where the specific problems are, and
grams at the same scale. Most probably one will why these require a certain treatment procedure.
| recognize from this that there are very little The same holds true of course to a varying degree
changes in all the skeletal parameters and at best for non-orthodontic medical specialists.
I some remaxkabie differences .;.v fita isfewdjrJ cAvrr- Tite orthodontist WI'IY see wi'tn one glance even
I
more. From the organization of the individual mea
acteristics. Real, dramatic changes of skeletal surements all values that indicate a Class II (sagittal
basal assessment,) and open bite tendency (vertical
measurements can only be found in growing
93
—
Frele Unlvorsitit Berlin Name: S, V; m
Fachborolch Z a h n - , M u n d - u n d Kt o f o r h e i l k u n d o ID-No.: /
flbt. fur K l e f o r o r t h o p a d l o u n d K 1 n d o r z ahnho 1 I k u n d o Birthday: 0 5 . 12.64
Graph i c r e p r e s e n t a t ion of cephalometrfc analysis
SNR
SNB
NPog-FH
RNB
WITS
NR-RPog
N'Pm'-DtUl
SN-SGn
SN-NL
SN-ML
RrGoMe
SGo:NMe
SN-OcP
IBB.9 .
I i -ML
130 12B LIB 100
6.i ; -2,1
1i-RPog X \
IB * 5 B
112.1 ■ 1 9.B 147.4
l i - l s •Jl 1 !■•• .-1 i 1
SB 30 MB" 150 1GB 17B
Ceph 1 from 29.B6.B7, age 22 years
3.38 Graphic representation of the cephalometric analysis described in the t e x t A l l necessary personal data is listed at the upper right
corner. In the lower left corner, it is stated when different cephalograms were taken, and how old the patient was each time. "Hie
numbers below each horizontal graph indicate the scale. The numbers above the graphs in the centre reflect the standard values. The
numbers left and right of the dotted vertical lines represent the values of the plus o r minus twofold standard deviation. The data shown
here was derived from a patient with an ideal occlusion and a normal extraoral feature. Surprisingly o r not, all parameters apart from
N P o g - F H are very close t o their respective standards.
94
Frele Unlversitat Berlin Name: M . r F.; m

F»chboro1ch Z i h n - , M u n d - u n d K t d e r n e ( I k u n d o ID-No.: /
Rbt. f u r K i o f o r o r t h o p a d l e und K l n d « r z a h n h a I 1kundo Birthday: 01.06.77
Graphic r e p r e s e n t a t i o n o f cephalometr1c analysis
SNA
SNB
NPog-FH
RNB
WITS
NR-flPog
N'Pm'-DtLM
SN-SGn
SN-NL
SN-ML
RrGoMe
SGo:NMe
SN-OcP
li-ML
li-flPog
H-ls
Coph 1 f r o m 1 2 . 0 7 . B 9 , age 12 years
]U9 Typical graphical representation of cephalometric data from a 12-year-old male patient with a Class II Division I malocdusion that
■ aggravated by an open bite. The curve that connects all individual values is strictly on the left side. It sometimes even crosses over the
unfold standard deviation (dotted) line.
95
Frele Universitht Berlin Name: R. , B. ; ui

F a c h b o r o l c h Zahn- , Mund-und K i e f orho 1 1 kunde ID-No.: /"
R b t . tQr K i a f a r o p t h o p l d t o und Kinderzahnhe11kunde Birthday: 12.03.79
Graphic representation of cephalometr i c analys is
SNR
SNB
NPog-FH
RNB
WITS
NR-RPog
N'Pm'-DtUl
SN-SGn
SN-NL
SN-ML
RrGoMe
SGorNMo
SN-OcP
1 I -ML
1i-RPog
l i - l s
Ceph 1 from 18.04.32, age 13 years
3.40 Graphical representation of cephalometric analysis of a 13-year-old female. The patient was diagnosed to have a Class III anomaly
with a negative overjet. The vertical basal relationship was decreased. Upper and lower incisors were lingually inclined. Again with one
glance the patients main problems become evident.
96
basal assessment) with a proclination of the incisors One reason not to use this graphic representation
will result in a line off-centre to the left (3.39). Class as a routine form is that, unfortunately, the mesh
III patients with a tendency to deep bite and very diagram is difficult to produce. It takes time and
upright incisors are indicated by an off-centre line skill to come up with an acceptable result. Part of
to the right (3.40). Surprisingly or not, many the difficulty is due to the fact that not every square
patients fit quire well in one of the two above men of the mesh contains a reference point (Landau et
tioned categories. Of course in Class II division 2 al, 1988). This means that the anatomical structures
patients the curve will swing after the sagittal basal in such a square have to be connected to squares
field from the left side to the right and remain there. that contain a reference point by free-hand drawing.
Curves that result from cephalograms taken at The more important reason not to use the
different times can be colour coded. Moorrees mesh routinely is that we became acquaint
ed with the Jacobson templates, and we feel that for
our purposes these can replace the mesh analysis.
The Jacobson templates are tracings to scale of
NON-NUMERICAL individuals with ideal occlusions and a pleasing
CEPHALOMETRIC ANALYSES appearance (3.42). All one has to do is to superim
pose the appropriate template on the actual tracing
There have long been approaches aimed at making or even the original X-ray image of a specific
an individual's morphological deviations from the patient. This superimposition takes place in the
norm even more visual by an adequate distortion of nasion-sella—basion triangle. On the nasion-basion
the patient's actual cephalometric tracing (Moorrees plane, a perpendicular line through the sella is con
1953,1991) (3.41). structed, and this line bisected; the resulting mark is
iC-.«fi«B)
PROPORTiONATI
TEMPLATE
J.4I Moorrees mesh analysis of a patient with a mucolipidosis III 3.42 Jacobson p r o p o r t i o n a t e template o f a small white
[diagnosis not verified): Class II sagittal-basal relationship with an (Caucasian series) person with normal occlusion and pleasing
| unproportional face height probably due t o a deficient posterior aesthetics. ( F r o m Jacobson, Proportionate Templates, Nola
facial length. Maxillary hypoplasia, remarkable bimaxillary Orthodontic Specialities; reprinted with permission.)
protrusion, steep inclination of the anterior cranial base and spatial
decrease between (posterior) nasal floor and basis cranii. Since in
the Moorrees analysis the profile is t o the left, it is oriented here
MM same way. The drawing on the lower right side indicates the
rectangle size; solid lines indicate original mesh size, broken lines
ndicate individual patient's size.
97
the starting point of the superimposition (3.43). This Differences also exist between various popula
midpoint is used mainly to average the error that tions, and this is why Jacobson developed additional
might be the consequence of a deviation in one of templates for American blacks. Differences that are
the three planes in the patient who is to be due to age and sex are reflected by a series of tem
compared with the standard. Beside this basic super- plates for children and adolescents (3,44). This
imposition, many others are feasible (Bench, 1972); series is to be used with common sense because head
e.g. on the maxilla and the mandible to find out size can vary widely within one age group. If an
about the dentoalveolar situation, on the soft tissue extremely small or large patient is compared with
to assess it. The Jacobson template analysis is com an age-matched template of average skull size, gross
mercially available and comes with an extensive deviations would be indicated everywhere, devia
description of how to use it. tions that in reality do not exist. To compensate for
It seems to be a problem to superimpose a this type of error, it is necessary to use a template of
template on different patients because the head size an older or younger child with a head size that
varies remarkably. However, this is not a structur matches the patient being examined. The compari
al problem but one of proportional enlargement or son will then lack some accuracy, but if this analysis
diminution. Therefore the templates come in four is used with critical common sense it can yield useful
sizes (small, average, large, and extra large). The results.
first step of its user is to find the template that fits Besides this restriction we feel that the Jacobson
best. This is done principally by comparing the template analysis is very advantageous for beginners
nasion-basion base line. Then the two other planes in the field of cephalometry, for communication
(NS and SBa) are included in this process of com with maxillofacial surgeons, for communication
parison until the template in which the anterior skull with patients, and even for experienced clinicians to
base corresponds optimally with that of our partic get an immediate overview about the major problem
ular patient is found. of a patient.
3.43 Superimposition of Jacobson template and individual tracing

(X-ray). First, NBa are aligned, then the template is moved up o r
down keeping NBa parallel until the mid S-J points (see 3.42) of
the tracing (X-ray) and the template are at the same level. (After
Jacobson, Proportionate Templates, Nola Orthodontic Specialities;
3.44 Jacobson proportionate template of a 10-year-old boy with

normal occlusion and favourable facial features. (After Jacobson,
Proportionate Templates, Nola Orthodontic Specialities; reprinted with
permission.)
98
CONCLUSION • have obviously escaped the general attention so

far, since they are seldom quoted elsewhere;
The primary intention of this chapter has not been > are relatively new and can serve well as a starting
to convince readers that our analysis is the optimal point for an extensive investigation of the litera
one, but to make the reader more critical of what he ture;
has done so far. We know which the best analysis * a personal affection to - mostly articles with the
for us at this time is, but we do not know which the present author as the (co)author.
best cephalomctric analysis in absolute terms is.
However, we are convinced that there are aspects
(hat characterize a cephalometric analysis that is Arnett GW, Bergman RT (1993) Facial keys to
superior to others. orthodontic diagnosis and treatment planning - part
A cephalometric analysis with a reasonable II. Am} OrthodDentofacial Orthop 103:395-41 1.
clinical base should:
• use reference points that are clearly defined and Bass NM (1987) Bass orthopedic appliance system.
easy to locate; Part 2. Diagnosis and appliance prescription. J Clin
• rely on more than one bone reference plane, since Orthod 21:312-20.
these planes are themselves variables;
• consider natural head position because resulting Baumrind S, Korn EL, West EE (1984) Prediction of
values then often reflect the actual appearance of mandibular rotation: An empirical test of clinical
the patient better; performance. Am J Orthod 86:371-85.
be clearly structured in skeletal and dentoalveo-
lar assessments and always distinguish between Behrents RB (1989) The consequences of adult cran-
the different planes (sagittal, vertical, transverse); iofacial growth. In: Orthodontics in an Aging
include as few measurements as possible, so that Society. Carlson DS (ed). Monograph 22.
an optimal overview is maintained at any time; Craniofacial Growth Series. (Center for Human
include a graphic representation, which is useful Growth and Development, The University of
for immediate understanding and which enhances Michigan, Ann Arbor.)
communication with non-orthodontic colleagues
and with patients; and Bench RW (1972) Seven-position serial cephalo
■ • be structured so that it can be changed without metric appraisal of normal growth and/or treatment.
difficulty when better insight requires an adap Proceedings. (Foundation for Orthodontic
tation. Research): 137-61.
w?ith rhis in mind, our very final advice is to use the Bergland O (1963) The bony nasopharynx. Acta
w >halometric analysis our readers have selected as
[thebest onc(s) with critical distance, common sense,
Odontol Scand 21(suppl 35).
and experience. Or, as the teachers of the author of Bishara SE, Jakobsen JR (1985) Longitudinal
this textbook chapter put it in a very short and changes in three normal facial types. Am j Orthod
drastic form: You cannot go by numbers! 88:466-502.
Bittner C, Panchcrz H (1990) Facial morphology

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Foodside DG, Linder-Aronson S, Lundstrom A,

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■OrtbodDentofacial Orthop 100:1-18.
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seitenbildanalyse der Abteilung fur Kieferorthopadie
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3:33-48.
CHAPTER 4
Cephalometric Methods for Assessment of

Dentofacial Changes
htnir E Bishara and Atbanasios E Athanasiou
INTRODUCTION the infant face is transformed into that of the adult

face by increases in size, by changes in proportion,
(During the last hundred years, orthodontics has pro and by adjustment in position. Today, Hellman's
cessed from being a simplistic treatment modality statement is universally accepted.
(for aligning teeth to a science of therapeutic inter- Cephalometry has significantly increased our
'ventioii in the complexities of the cranial, facial, and understanding of normal facial growth as well as the
(dental structures. The study of the morphological outcome of orthodontic treatment, particularly
relationships of the various parts of the face has alsothrough the use of cephalometric superimpositions.
[developed from its early period of craniometry - an A cephalometric superimposition is an analysis of
janthropologic three-dimensional method of mea lateral cephalograms of the same patient taken at dif
suring the skull and head - to roentgenographic ferent times. These superimpositions are used to
I cephalometry - a two-dimensional radiographic evaluate a patient's growth pattern between different
study of the skull. More recently, attempts have been ages and to evaluate changes in the dentoalveolar and
| made to digitize the investigative methods used and basal relationships after a course of orthodontic or
reconstruct three-dimensional images of the head surgical treatment. However, if such superimpositions
and face through the use of computers and serial are to be meaningful, the appropriate procedures
jtomograms (Marsh and Vannier, 1990). must be exxecuted in a technically accurate and bio
[ In 1931, Broadbent in the USA and Hofrath in logically sound manner. Furthermore, such cephalo
Germany introduced the technique of radiograph- metric procedures and evaluations should be
tic cephalometry. Since then, clinicians and research considered in the light of:
ers have adopted and routinely used this valuable • rhe pretreatment objectives;
| tool on orthodontic patients in order to analyse • the orthodontic treatment modalities used; and
j underlying dentofacial relationships. In addition, • the long-term follow-up of the treatment results
I cephalometrics is used to gain a better understand- during the retention and post-retention periods.
[ing of the facial changes that accompany growth
[ and/or orthodontic treatment.
Since the early application of cephalometry for METHODS OF ASSESSING DENTO
studying dentofacial growth, there have been dis FACIAL CHANGES
agreements about how and when the dimensions of
die face change. Brodie (1941) and Broadbent When evaluating the dentofacial changes that occur
i (1941) felt that dentofacial growth patterns are as a result of growth or treatment, orthodontists are
established at a very early age and thereafter are interested in observing specific areas of alterations
[subject to proportional changes. Downs (1948) and (Kristensen, 1989). As a result, cephalometric super-
Ricketts (1975) pointed out that several angles and impositions involve the evaluation of:
(dimensions change with age but in an orderly and • changes in the overall face;
[progressive manner. However, the view that there • changes in the maxilla and its dentition;
lire no differential growth rates in the face was not • changes in the mandible and its dentition;
shared by everyone. The concept that had been • amount and direction of condylar growth; and
expressed earlier by Hellman (1935) suggested that • mandibular rotation.
105
\
An early method used to determine the changes placement of metallic implants in the maxilla and
that occur in the dentofacial complex was the com mandible for subsequent use as stable structures has
parison of linear and angular measurements from been advocated by researchers (Bjork, 1968) (4.1).
consecutive cephalograms. The major disadvantage For fairly obvious reasons, it is n o t recommended
of this method is that it does not accurately portray that such implants be used routinely as a means of
the actual changes in the dentofacial structures; determining the changes t h a t occur as a result of
rather it reflects the relative changes between specific growth and treatment. However, information
cephalometric l a n d m a r k s located on the radi- gathered from earlier implant studies (Bjork, \%3)
ographic profiles of various bones. As an example, a s well a s studies o n h u m a n a u t o p s y materials
the angle SNA not only represents the changes at (Melsen, 1974; Melsen and Melsen, 1982) are useful
point A, but also the spatial changes that occur at in identifying which areas are relatively stable (i.e.
areas where the changes are of relatively small mag
sella and at nasion. Of course, if numerous angles,
nitude). O n the other h a n d , cephalometric super-
lines, a n d ratios a r e measured and calculated, an
impositions performed on patients w h o have
understanding of the changes in the facial structures
completed their g r o w t h are likely to be more
is conceptually possible. Such a process, however, is
accurate.
time consuming and clinically impractical.
The use of serial superimpositions from cephalo In addition to quantitative information, cephalo
grams that have been taken at different times is one metric superimpositions can provide important
method for accurately determining the relative qualitative information. However, for these judge
changes in the face. For a meaningful interpretation ments to be useful, they have t o be obtained from
of these superimpositions, they have to be registered consecutive cephalograms taken under identical
on stable reference areas. Unfortunately, areas in the conditions of magnification, head position, and
craniofacial complex that d o not change during the radiological exposure; furthermore, the tracing of
period of growth c a n n o t be easily identified. The the superimpositions must be accurate. According
4.1 The p l a c e m e n t o f m e t a l l i c implants in the maxilla and

mandible has been used t o create stable structures. (A) Implants
are inserted in four regions of the mandible: one in the midline of
the symphysis, t w o under the first o r second premolar or first
molar on the right side, one on the external aspect of the right
ramus, and one under the second premolar on the left side. (BJ
Implants are inserted in four zones in the maxilla: before eruption
of the permanent incisors, one on each side of the hard palate,
behind the deciduous canines, after eruption of the permanent
incisors, one o n each side of the median suture, under the anterior
nasal spine, and t w o o n each side in the zygomatk process of the
maxilla. (After Bjork, 1968; reprinted with permission.)
106
Ceph lometric Methods for Assessment of Dentofacial Changes
to Broadbent et al (1975), when tracing serial films, EVALUATION OF T H E OVERALL

one may start with the youngest pair and follow the C H A N G E S I N T H E FACE
child rovvards maturity, or start at the most mature
stage and work backwards. Either method allows
the examiner to observe gradual morphological BACKGROUND
changes. The benefits of sequential progression or
regression are forfeited if the cases are not traced in Cranial structures have traditionally been used for
order. these superimpositions based on the fact that both
It is of great importance that exactly the same the neurocranium and its related cranial base
structures and their corresponding radiographic achieve most of their growth potential at a relatively
shadows be traced in the consecutive cephalograms early age. At birth, the intersphenoidal and intereth-
that are to be evaluated. One of the prerequisites of moidal synchondroses are closed. By six or seven
tracing is ro locate precisely the outlines of the years of age, the only synchondrosis remaining open
relevant structures and to eliminate the confusing, is the spheno-occipital synchondrosis. As a result,
unusable details. there is relatively little anteroposterior change in the
ethmoidal portion of the anterior cranial base
Colour coding f o r t r a c i n g (Knott, 1971). From this age onwards, any changes
border to facilitate identification of consecutive that occur on the bone surfaces are due to remodel
cephalograms the following colour code has been ling. Therefore, this part of the cranial base is con
suggested by the American Board of Orthodontists sidered to be relatively stable.
11990):
i •pretreatment - black;
f progress- blue; SUPERIMPOSITION METHODS
j 'end of treatment - red;
j ' retention - green. Broadbent triangle
The Broadbent triangle (Na-S-Bo) and its registra
tion point R were among the first structures used for
superimpositions to determine overall changes. With
this method, the two tracings are oriented so that
the R points are registered and the Bolton planes
(Bo-Na) are parallel (Broadbent, 1931) (4.2).
Sella-nasion line
Another method of superimposition orients the two
tracings on the Sella-nasion line with registration at
sella (American Board of Orthodontics, 1990) (4.3).
This method provides a composite view of the
amount of growth change during the period
between the two films; it is reasonably accurate as
long as the growth change at nasion follows the
linear extention of the original sella-nasion line.
The major disadvantage of these methods of

superimposition is that they incorporate areas of the
42 Use of the Broadbenc triangle (N-S-Bo) and its registration cranial base that continue to change during most of
pontR (arrow) for superimposition to determine overall changes. the growing years. Growth at the spheno-occipital
tai this method, the two tracings are oriented with the R points synchodrosis (Khott, 1971) as well as bone remod
ngistered and the Bolton planes (Bo-N) parallel. (After Broadbent eling at Nasion and Sella are responsible for these
1975: reprinted with permission.) changes. Nasion is displaced forward during remod-
107
eling but with no consistent superioinferior direc growth. According to Coben (1986), the relation
tion. Most of the changes in the position of nasion ships among the position of the head in normal
are due to the enlargement of the frontal sinus, and posture, the visual axis of the eyes, and the anterior
consequently the upward or downward migration cranial base do not change. As a result, serial
of the frontonasal suture would result in superim- tracings should be registered at basion and oriented
position errors (Nelson, 1960; Knott, 1971). Sella with the S-N planes parallel. The line from basion
turcica also undergoes eccentric remodelling during drawn parallel to the original Frankfort horizontal,
adolescence and beyond, and this results in signifi or the mean Frankfort horizontal of the several radi
cant changes in the configuration of the fossa ographs, establishes the constant SN-FH relation
(Melsen, 1974). As a result, the position of the ship and the Basion Horizontal plane of the series.
midpoint of the sella turcica (point sella) moves Each subsequent co-ordinate tracing film may be
either downwards and backwards or straight down superimposed by simply aligning the co-ordinate
wards. Similarly, Bolton point is frequently obscured grids that have been especially designed for this
by the mastoid process in the teenage years purpose (Coben 1979) (4.4).
(Broadbentetal, 1975).
Basion-Nasion plane
Basion H o r i z o n t a l The use of Basion-Nasion plane as an area of reg
Cohen (195J, 1986) presented the Basion istration for overall evaluation of the dentofacial
Horizontal concept. The Basion Horizontal is a changes has been suggested by Ricketts et al (1979).
plane constructed at the level of the anterior border According to Ricketts, if the superimposition area
of the foramen magnum parallel to Frankfort hor is the Ba-Na line with registration at CC point (the
izontal. With this method, basion is used as the point where the basion-nasion plane and the facial
point of reference for the analysis of craniofacial axis intersect), it is possible to evaluate changes in
4.4 According t o the Basion Horizontal concept, serial tracing!

should be registered a t basion and o r i e n t e d w i t h S-N planes
parallel. T h e line f r o m basion d r a w n parallel t o the original
F r a n k f o r t h o r i z o n t a l o r the mean F r a n k f o r t horizontal of the
several radiographs establishes the constant S N - F H relationship
and the Basion Horizontal plane of the series. Each of the two
4.3 O r i e n t a t i o n o f three subsequent tracings o n the sella-nasion subsequent co-ordinates o n the tracing may be superimposed ty
m e r e l y aligning the specially designed c o o r d i n a t e grids. This
line and with registration at sella. This example corresponds t o the
example c o r r e s p o n d s t o the p r e t r e a t m e n t (black) and end of
pretreatment (black), end of treatment (red), and retention (green)
treatment (red) phases of an orthodontic patient.
phases of orthodontic therapy.
108
Cephalometric Methods for Assessment of Dentofacial Changes
facial axis (BA-CC-GN), in the direction of chin REFERENCE STRUCTURES FOR OVERALL
>wth, and in the upper molar position (4.5). FACE SUPERIMPOSITIONS
Melsen (1974), on the other hand, has observed
it the position of Basion is influenced by the Nelson's (1960) cephalometric study and Melsen's
lodeling processes o n the surface of the clivus (1974) histological investigation identified various
id on the anterior border of the foramen magnum, bony surfaces in the anterior cranial base that are
well as by displacement of the occipital bone. suitable for accurate superimpositions. These
^placement of the occipital bone is associated with surfaces undergo relatively minimal alterations
growth in the spheno-occipital synchondrosis. during the growth period and have been called
Isen's histological investigation revealed appo- stable structures or reference structures. They
>n on the anterior border of the foramen include (4.6):
ignum, with simultaneous resorption on the inner • the anterior wall of sella turcica;
rface of the basilar part of the occipital bone and • the contour of the cribiform plate of the ethmoid
tsition on its outer surface. bone (lamina cribrosa);
• details in the trabecular system in the ethmoid cells;
Because nasion, sella, and basion move during • the median border of the orbital roof; and
rowth, the methods of overall super imposition on • the plane of the sphenoid bone (planum sphe-
S-Na or Ba-Na lines have a low degree of validity, noidale).
although they have high degree of reproducibility For registration purposes, Nelson (1960) recom
(Kristensen, 1989). (See chapter 5 for a discussion mended the use of the midpoint between the right
of validity and reproducibility of methods.) and left shadows of the anterior curvatures of the
great wings of the sphenoid bone where they intere-
sect the planum.
4.6 Bony surfaces in the anterior cranial base that are suitable for
accurate superimposition. These surfaces undergo relatively
minimum alterations during growth and are called stable structures
or reference structures. They include:
1 the anterior wall of sella turcica
2 the contour of the cribriform plate of the ethmoid cells (lamina
cribrosa)
15 For superimpositions, Ricketts used the BA-NA line with 3 details in the trabecular system in the ethmoid cells
jnpscration at CC point (point where the BA-NA plane and the 4 the median border of the orbital roof
fid axis intersect). Changes in the facial axis (BA-CC-GN), in 5 the plane of the sphenoid bone (planum sphenoidale).
I (he direction of the chin point and in the upper molar position, can
Kt evaluated. (After Ricketts et al, 1979; r e p r i n t e d w i t h
■mission.)
109
Orthodontic Qephalometry
STEP-BY-STEP EVALUATION OF W H A T CAN W E LEARN FROM

THE OVERALL FACE OVERALL SUPERIMPOSITIONS?
The approach for the overall superimposition on Cranial base superimpositions provide an overall
stable cranial structures includes the following steps assessment of the growth and treatment changes of
(4.7): the facial structures, including the amount and
1. Place tracing paper on the first cephalogram and direction of maxillary and mandibular growth or
stabilize it with tape. Use black tracing pencil to displacement, changes in maxillary-mandibular
complete the tracing, which should include as relationships, and the relative changes in the soft
many of the above-mentioned stable structures as tissue integument (specifically the nose, lips, and
possible. chin). In addition, cranial base superimpositions
2. Trace the second cephalogram with either a blue provide information on the overall displacement of
or red tracing pencil, depending on whether it is the teeth. As mentioned before, this technique will
a progress or post-treatment record. not identify specific sites of growth, but it will
3. Superimpose the second tracing on the first one, provide a quantitative directional appraisal of the
again using as many as possible of the stable translatory changes that have occurred in the
structures of the cranial base that have been various facial structures.
clearly identified from both cephalograms.
Register on the midpoint between the right and
left shadows of the greater wing of the sphenoid ASSESSMENT OF CHANGES IN
as they intersect the planum sphenoidale. TEETH POSITION
Stabilize the tracing with tape.
It needs to be realized that the cranial base super-
This method of overall superimposition presents a impositions do not provide for an assessment of the
high degree of validity and a medium to high degree changes in the position of the teeth within the
of reprod ucibility. maxilla or mandible. In order to obtain this infor
mation, maxillary and mandibular superimpositions
are required.
110
Cepbalometric Methods for Assessment of Dentofacial Changes
53
1
1 -52
' Jilm
4H|
■P m ^WB
■
a
^^ jfl
Îftb— ""^^^H
4.7 A step-by-step approach for the overall superimposition on stable cranial

structures. (A) Pretreatment cephalogram; (B) Pretreatment tracing on cephalo-
gram; (C) Pretreatment tracing; (D) Progress cephalogram; (E) Progress tracing on
cephalogram; (F) Progress tracing; (G) Superimposition of pretreatment and
progress tracings.
E.H.
Pre-Trealmeni
Progress
111
MAXILLARY SUPERIMPOSITIONS 3. Superimposition along the palatal plane regis

tered at the pterygomaxillary fissure (Moore,
Background 1959) (4.10).
The purpose of maxillary superimpositions is to 4. Superimposition on the outline of the infratem-
evaluate the movement of the maxillary teeth in poral fossa and the posterior portion of the hard
relation to the basal parts of the maxilla. A number palate (Riedel, 1974) (4.11).
of methods for superimposing the maxillary struc 5. Superimposition registering the maxilla on the
tures have been suggested, including the following: common Ptm co-ordinate, maintaining the Basion
1. Superimposition along the palatal plane regis Horizontal relationship (Coben, 1986) (4.12).
tered at anterior nasal spine (ANS) (Broadbent, 6. Superimposition on the best fit of the internal
1937; Moore, 1959; Salzmann, 1960; Ricketts, palatal structures (McNamara, 1981) (4.13).
1960, 1972,1981; McNamara, 1981) (4.8). 7. Superimposition on metallic implants (Bjork and
2. Superimposition on the nasal floors with the films Skieller, 1976a, b) (4.14).
registered at the anterior surface of the maxilla 8. The structural superimposition on the anterior
(Downs, 1948; Brodie, 1949) (4.9). surface of the zygomatic process of the maxilla
(Bjork and Skieller, 1976a, b; Luder, 1981) (4.15).
4.8 Maxillary superimposition along the palatal plane registered at 4.9 S u p e r i m p o s i t i o n o n the nasal f l o o r s w i t h the traci
ANS. registered at the anterior surface of the maxilla.
4.10 Maxillary superimposition along the palatal plane registered 4.1 I Maxillary superimposition registered on the outline of the
at the pterygomaxillary fissure. infratemporal fossa and the posterior p o r t i o n of the hard palate.
112
4.13 Maxillary superimposition on the best fit o f the internal

palatal structures. (After McNamara, 1981; r e p r i n t e d w i t h per
mission.)
412 Superimposition registering the maxilla on the c o m m o n Ptm

pordinate and maintaining the Basion H o r i z o n t a l relationship.
k illustrates the maxillary contribution t o midface depth and the
■rizontal and vertical changes of the palate and the maxillary
■notion relative to both Ptm and the foramen magnum plane of
orientation (Basion Horizontal).
NSLg 3 —i
NSLA ■ . *
\ P
rrr
■
.
\Ji -
II ^
v y
4.15
■
/ \f
The structural superimposition on the anterior surface of
.
the zygomatic process of the maxilla.
14 Maxillary superimposition o n metallic implants. G r o w t h of

maxilla and the dental arch is analysed by means of implants.
BterBjork, 1968; reprinted with permission.)
113
The various methods of maxillary superimpositions basal part of the bone. However, this method of
that use either the palatal plane between the anterior maxillary superimposition is characterized by a low
nasal spine and the posterior nasal spine (ANS-PNS degree of validity and only a medium degree of
line) or the best fit on the maxilla are compromised reproducibility (Kristensen, 1989).
by the remodelling of the palatal shelves. It has been On the other hand, Bjork and Skieller (1977b),
shown that the hard palate undergoes continuous using implants, suggested the use of a structural
resorption on its nasal surface and apposition on the method of superimposition in order to evaluate
oral side, making most of these methods of super- maxillary growth and treatment changes (4.15),
impositions unsatisfactory/ (Bjork and Skieller, With this approach, the tracings are superimposed
1977a, b) (4.16). Furthermore, registration on either on the anterior contour of the zygomatic process of
ANS or PNS should be avoided, since both these the maxilla, which shows relative stability after the
structures are known to undergo significant antero- age of eight. The second film is oriented so that the
posterior remodelling (Bjork and Skieller, 1977a). resorptive lowering of the nasal floor is equal to the
The best fit method provides a higher degree of apposition at the orbital floor.
validity than the ANS-PNS line, since the palatal Nielsen (1989) examined the validity and relia
structures used for superimposition incorporate the bility of the structural method of superimposition
4.16 Mean growth changes from four years until adult age in nine
boys, measured f r o m the lateral implants. (After Bjork and Skieller,
1977a; reprinted w i t h permission.)
Su - sutural lowering of the maxilla
O - apposition at the floor o f the o r b i t
A - appositional increase in height of the alveolar process
Re - resorptive lowering of the nasal floor
C - apposition at the infra zygomatic crest
114
and compared it to the implant and best fit methods. between the structural and the implant methods in
Hie best fit superimposition w a s made as the the vertical plane. In the horizontal direction,
optimal fit of the hard palate with the nasal floors however, the structural method on average demon
aligned and registered at ANS. The various super- strated a posterior displacement of the reference
impositions were constructed from tracings points by an average of 0.5 mm.
obtained from cephalograms taken on 18 subjects As a result, it has been concluded that the struc
at 10 and 14 years of age. Nielsen found that the tural method for superimposing head films is a valid
best fit method significantly underestimates the and reliable method for determining maxillary
vertical displacement of both the skeletal and dental growth and treatment changes (Nielsen, 1989). The
landmarks as a result of the remodelling of the major disadvantage of using the structural method
maxilla (4.17, 4.18). The study further demon is that the zygomatic process of the maxilla is char
strated that, with both the implant method and the acterized by double structures, which makes it dif
structural method, ANS showed twice as much ficult to identify accurately and hence to trace the
vertical displacement as PNS. On the other hand, no construction line. As a result, this method has a low
statistically significant differences were found degree of reproducibility.
IMPLANT-BEST FIT DIFFERENCES (TIMEPOINT II) STRUCTURAL-BEST FIT DIFFERENCES {TIMEPOINT
PNS PNS
1.39 ANS
t 0.94
initial * Initial
Best Fit n Best Fit

0-—™ implant I Structural
4.17 Mean and standard deviations of differences in displacement 4.18 Mean and standard deviations of differences in displacement
ofikeletal and dental landmarks between the implant and the best of skeletal and dental landmarks between structural and best f i t
It super-impositions during a four-year p e r i o d ( N = I 8 ) . ( A f t e r supe rim positions during a four-year period ( N = I 8 ) . (After Nielsen,
tfelsen, 1989; reprinted with permission.) 1989; reprinted with permission.)
115
W H E R E T O SUPERIMPOSE I N T H E T h e structural m e t h o d of maxillary superimposi

MAXILLA? tions has a medium t o high degree of validity and
low degree of reproducibility (Kristensen, 1989).
Two methods for superimposing the maxillary struc
tures are recommended - the structural method and Modified best fit method of superimposing the
a modified best fit method. maxillary structures
If the details of the zygomatic process of the maxilla
The structural m e t h o d of superimposing the are not clearly identifiable, a modified best fit
maxillary structures method is recommended. The superimpositions are
The use of the structural method is recommended if made on the nasal and palatal surfaces of the hard
the details of the zygomatic process of the maxilla palate in an area that is not significantly influenced
are clearly identifiable in both cephalograms. T h e by incisor tooth movement. The approach for max
approach for maxillary superimpositions on stable illary superimpositions by means of the best fit
structures includes the following steps (4.19): method include the following steps (4.20):
1. Place a cellophane tracing paper on each cephalo- 1. Trace t h e maxillary structures, including the
gram. Trace the anterior contour of the zygomatic outline of the palate, the first permanent molars,
process and construct a line that is tangential to the entrance of the incisal canal (when it can be
it. When two contours are present, bisect them to visualized), and the most labially positioned
trace the midline between them. central incisor on the t w o consecutive cephalo
2. O n each c e p h a l o g r a m , trace the c o n t o u r of the grams, using the appropriate colours.
palate, the maxillary first molar, the most labially 2. Place t h e second tracing over the first one and
positioned central incisor, the zygomatic process, adjust it to have the following structures arranged
the floor of the orbit, N - S line, a n d the con in a best fit alignment:
struction line (which is a line tangential t o the • the contour of the oral part of the palate;
anterior contour of the zygomatic process). The • the contour of the nasal floor; and
tracing from the first cephalogram is d r a w n in • the entrance of the incisal canal.
black and the tracing from the second tracing in
blue or red depending on whether it is a progress Stabilize the two cephalograms together by means
or post-treatment record. of a tape.
3. The two tracings should be superimposed on each As stated earlier, when using the best fit method,
o t h e r on t h e construction line to determine the it needs t o be remembered t h a t the downward
a m o u n t of apposition at the floor of the orbit. remodelling of the nasal floor should be accounted
Move the superimpositions so that the amount of for from the overall superimpositions on the cranial
resorption at the nasal floor is equal to the appo base. Furthermore, the molar eruptions are under
sition at the floor of t h e orbit. Stabilize the estimated by 3 0 % and the incisor eruptions are
tracings together with a tape. underestimated by 5 0 % .
4 . T h e a m o u n t of maxillary rotation can be esti The best fit method has a low degree of validity
mated from the two N - S lines. The angle formed and a medium degree of reproducibility (Kristensen,
between the lines expresses t h e rotation of the 1989).
maxilla. For instance, if the two lines cross ante
riorly then the rotation has taken place in an
anterior direction.
I 16
4.19 A step-by-step approach for maxillary superimpositions on

G.R.
Pre-Trcatment stable structures. (A) Pretreatment cephalogram (maxillary area);
Pose-Treatment (B) P r e t r e a t m e n t m a x i l l a r y t r a c i n g o n c e p h a l o g r a m ; (C)
P r e t r e a t m e n t m a x i l l a r y tracing; ( D ) P o s t - t r e a t m e n t m a x i l l a r y
cephalogram; (E) Post-treatment maxillary tracing on cephalogram;
(F) Post-treatment maxillary tracing; (G) Superimposition o n stable
structures of pretreatment and post-treatment maxillary tracings.
117
4.20 A step-by-step approach for a modified best fit

method of maxillary superimposition. (A) Pretreatment
c e p h a l o g r a m ( m a x i l l a r y a r e a ) ; (B) Pretreatment
maxillary tracing o n cephalogram; (C) Pretreatment
maxillary tracing; (D) Progress maxillary cephalogram;
(E) Progress maxillary t r a c i n g on cephalogram; (F)
Progress maxillary tracing; (G) Best fit superimposition
of pretreatment and progress maxillary tracings.
118
MANDIBULAR SUPERIMPOSITIONS Stable structures for superimposition on the

mandible
Background From their implant studies, Bjork (1963,1969) and
the purpose of mandibular superimpositions is to Bjork and Skieller (1983) have indicated that the fol
evaluate the movement of the mandibular teeth in lowing structures are relatively stable and could be
Relation to the basal parts of the mandible. A used for superimposition purposes (4.21):
wumber of areas have been suggested for superim- 1. The anterior contour of the chin (area 1).
Ipositions (Salzmann, 1972), including: 2. The inner contour of the cortical plates at the
• the lower border of the mandible; inferior border of the symphysis and any distinct
I a tangent to the lower border of the mandible; trabecular structure in the lower part of the sym
and physis (area 2),
• the constructed mandibular plane between 3. Posteriorly, the contours of the mandibular canal
Menton and Gonion. (area 3) and on the lower contour of a mineral
ized molar germ (area 4). The latter structure can
)wever, these methods are not very accurate in only be used from the time of initial mineraliza
escribing the changes within the mandible itself, tion of the crown until the beginning of root for
mse of the significant remodelling that occurs at mation. Before and after these two stages of
mandibular border (Bjork, 1963). development, it was observed that the tooth germ
Superimposition on the mandibular plane is a significantly changes its position (Bjork and
I method of low degree of validity, but of high degree Skieller, 1983).
|of reproducibility (Kristensen, 1989).
4.21 The structures in the niandibular corpus used f o r mandi

bular superimpositions. (After Bjork, 1969; r e p r i n t e d w i t h per
mission.)
119
Step-by-step approach for mandibular to the stable structures listed earlier, and it therefore
superimpositions exhibits great variation. This remodelling is char
The recommended approach for mandibular super- acterized by apposition in the anterior part and
impositions by using stable structures includes the some resorption in the posterior part, i.e. the gonion
following steps (4.22): area (Bjork, 1969).
1. On each of the two cephalograms, trace the fol
lowing structures using the appropriate colours: Evaluation of a m o u n t and direction o f
• the symphysis with the inner cortical bone; condylar growth and evaluation of mandibular
• the inferior and posterior contour of the rotation
mandible; Condylar growth can be evaluated from the
• the point Articulare; mandibular tracing if the head of the condyle can be
• the anterior contour of the ramus; clearly identified. Since the condyles are difficult to
• the mandibular canal; identify on a lateral cephalogram taken in centric
• third molar tooth buds before root formation; occlusion, a supplementary lateral cephalogram,
• the most labially positioned lower incisor; and taken with the mouth maximally open, can provide
• the first molars. the best imaging of the condylar head. In order to
2. If the four stable structures described earlier are avoid exposing the patient to extra radiation, point
all clearly identifiable on the cephalogram, they Articulare can be used as a substitute for this eval
should all be used for superimposition purposes. uation^ Changes at Articulare will reflect approxi
However, in some patients the third molars are mate changes of the condylar area and provide some
congenitally missing, while in others tooth devel information concerning the amount and direction
opment might not yet have shown crown miner of condylar growth. The recommended approach
alization or the roots may have already started for assessing true mandibular rotation includes the
forming. In these cases, the third molar tooth following steps (4.23):
germ is not a useful structure for superimposition 1. On each of the two cephalograms trace the fol
purposes. Similarly, the outline of the mandibu lowing structures using the appropriate colours:
lar canal is often difficult to identify in consecu • the symphysis with cortical bone;
tive lateral cephalograms. A further problem is • the inferior and posterior contour of the
that the shadows of the right and left sides can mandible;
overlap, further confusing the picture. As a result, • the point Articulare;
the only surfaces that can be reliably and consis • the anterior contour of the ramus;
tently used for the purpose of superimposition are • the mandibular canal;
the inner cortical structure of the inferior border • third molar tooth buds before root formation;
of the symphysis and the anterior contour of the • the most labially positioned lower incisor;
chin. • the first molars; and
3. Place the last cephalogram on the first one and • the N - S line.
adjust it in relation to the stable structures of the 2. If the four stable structures described earlier are
mandible. Then stabilize the two cephalograms all clearly identifiable on the cephalogram, they
together with tape. should all be used for superimposition purposes.
3. Place the last cephalogram on the first one and
The method of using stable structures for mandibu adjust it in relation to the stable structures of the
lar superimpositions is characterized by medium to mandible. Then stabilize the two cephalograms
high degree of validity and medium to high degree together by means of a tape. The true mandibu
of reproducibility (Kristensen, 1989). lar rotation can be evaluated by the changes in
When the stable structures that are intended to the N - S lines between the two consecutive
be used for superimposition are not easily identifi mandibular tracings. The angle expresses the
able, the lower border of the mandible can be used amount of mandibular rotation. For instance, if
for orientation purposes. However, it needs to be they cross anteriorly, the mandible has rotated
realized that the lower border of the mandible anteriorly.
undergoes significant remodelling when compared
120
A.D.
Progress
fvy \
V K
\
V 3 |fl
1/
i 11
4.22 A scep-by-step approach for mandibular superimposicions on stable structures:

A.D.
(A) Pretreatment cephalogram (mandibular area); (B) Pretreatment mandibular tracing
P re-Treatment
on cephalogram; (C) Pretreatment mandibular tracing; (D) Progress mandibular
Progress
cephalogram; (E) Progress mandibular tracing on cephalogram; (F) Progress mandibular
tracing; (G) Structural superimposition of pretreatment and progress mandibular
tracings.
121
■ i -
r..*. C.R.
3 h o TrrulBCnt — - ^H
W' -'ijMisM ^BjkfW?
^B
£j* A
w ~^B jj
^MH r ■
tf ^hiî
II V
■ A ^ . • JK
£■ f^~>A * V
C.R.
jiSil—
4.23 A step-by-step approach for determining mandibular rotations. (A) Pretreatment

C.R. cephalogram; (B) Pretreatment tracing o n cephalogram including mandibular area and N-S
Pr» ICMtSMt -
Pom t r c . K w o t line (NSL1); (C) Pretreatment tracing including mandibular area and N - S line (NSL1); (D)
P o s t - t r e a t m e n t c e p h a l o g r a m ; (E) P o s t - t r e a t m e n t t r a c i n g o n cephalogram including
mandibular area and N-S line (NSL2); (F) Post-treatment tracing including mandibular area
and N - S line (NSL2); (G) Structural superimposition o f pretreatment and post-treatment
Mi
mandibular tracings. T h e true mandibular rotation can, thus, be evaluated by the changes
in t h e N - S lines between the t w o consecutive mandibular tracings. The angle expresses
the amount o f mandibular r o t a t i o n . If they cross anteriorly, the mandible has rotated |
anteriorly.
122
r
CONCLUSION
\c Methods for Assessment of Dentofacial Changes
Bjork A, Skieller V (1976) Postnatal growth and

I In this chapter an attempt has been made to present development of the maxillary complex. In:
| the scientific basis on which accurate superimposi- McNamara JA Jr (ed) Factors Affecting the Growth
jfions can be made. If the tracings are not accurate of the Midface. Monograph No. 6. (University of
and the superimpositions and registrations are not Michigan: Ann Arbor) 61-99.
made on radiographic structures that have been
proved to be relatively stable and reliable, the super- Bjork A, Skieller V (1977a) Growth of the maxilla
impositions can be manipulated to show anything in three dimensions as revealed radiographically by
the operator wants to show. the implant method. Br J Orthod 4:53-64.
Short of using metallic implants, superimposi
tions performed using the suggested approaches rep Bjork A, Skieller V (1977b) Roentgencephalometric
resent the best available methods for interpreting the growth analysis of the maxilla. Trans Eur Orthod
changes in the dentofacial complex that have Soc 7:209-33.
mccurred as a result of growth or treatment.
To perform an accurate superimposition, one has Bjork A, Skieller V (1983) Superimposition of
to have an excellent knowledge of the anatomy of profile radiographs by the structural method. In:
the dentofacial and cranial structures as well as of Normal and Abnormal Growth of the Mandible.
die radiographic interpretation of these structures. Eur J Orthod 5:40-6.
This is essential, since the radiograph is a two-
Mimensional image of three-dimensional structures, Broadbent BH (1931) A new X-ray technique and
(and the view it provides in profile. Without such its application to Orthodontia. Angle Orthod
Knowledge and understanding, radiographic inter 1:45-66.
pretations become a guessing game rather than the
pence that cephalometrics is supposed to be. Broadbent BH (1937) Bolton standards and tech
[Furthermore, the scientific knowledge should be nique in orthodontic practice. Angle Orthod
[supplemented by the manual skills needed to draw 7:209-33.
pe structures that have been identified accurately.
Broadbent BH (1941) Ontogenic development of
occlusion. Angle Orthod 1 1 : 2 2 3 ^ 1 .
REFERENCES
Broadbent BH Sr, Broadbent BH Jr, Golden WH
[American Board of Orthodontics (1990). Exami- (1975) Bolton Standards of Dentofacial
mtkm Information Manual. (American Board of Developmental Growth. (CV Mosby: St Louis.)
.Orthodontics: St Louis.)
Brodie AG (1941) On the growth pattern of the
Bjork A (1963) Variations in the growth pattern of human head from the third month to the eighth year
[the human mandible: Longitudinal radiographic of life. Am J Anat 68:209-62.
study by the implant method. / Dent Res
12:400-11. Brodie AG (1949) Cephalometric roentgenology:
history, technics and uses. J Oral Surg 7:185-98.
■Study of facial growth in children. Am J Phys Coben SE (1955) The integration of facial skeletal
mbropol 29:243-54. variants. Am) Orthod 41:407-34.
Bjork A (1969) Prediction of mandibular growth Coben SE (1961) Growth concepts. Angle Orthod
fetation. Am J Orthod 55:585-99. 31:194-201.
123
Orthodontic Cephdlometry
Coben SE (1979) Basion Horizontal coordinate

tracing films./ C/m Orthod 13:598-605. Melsen B, Melsen F (1982) The postnatal develop
ment of the palatomaxillary region studied on
Coben SE (1986) Basion Horizontal: An integrat human autopsy material. Am] Orthod 82:329-42.
ed Concept of Craniofacial Growth and
Cephalometric Analysis. (Computer Cephalometric Moore AW (1959) Observations on facial growth
Associated: Jenkintown, Pennsylvania.) and its clinical significance. Am J Orthod
45:399-423.
Downs WB (1948) Variations in facial relations:
their significance in treatment and prognosis. Am Nelson T O (1960) Analysis of facial growth utiliz
J Orthod 34:812-40. ing elements of the cranial base as registrations. Am
J Orthod 46:379.
Downs WB (1952) Cephalometrics in case analysis
and diagnosis. Am} Orthod 38:162-82. Nielsen IL (1989) Maxillary superimposition: A
comparison of three methods for cephalometric
Hellman M (1935) The face in its developmental evaluations of growth and treatment change. Am]
career. Dental Cosmos 77:685-99. Orthod Dentofac Orthop 95:422-31.
Hofrath H (1931) Die Bedeutung der Rontgenfern Ricketts RM (I960) The influence of orthodontic
und Abstandandsaufname fur die Diagnostic der treatment on facial growth and development. Angle
Kieferanomalien. Fortschr Ortodont 1:232-57. Orthod 30:103-32.
Knott VB (1971) Changes in cranial base measures Ricketts RM (1972) An overview of computerized
of human males and females from age 6 years to cephalometrics. Am] Orthod61:1-28.
early adulthood growth. Growth 35:145-58.
Ricketts RM (1975) New perspectives on orienta
Kristensen B (1989) Cephalometric Superim- tion and their benefits of clinical orthodontics - Part
position: Growth and Treatment Evaluation. (The 1. Angle Orthod 45:238-48.
Royal Dental College: Aarhus.)
Ricketts RM (1981) Perspectives in the clinical
Luder HU (1981) Effects of activator treatment - application of cephalometrics. Angle Orthod
evidence for the occurrence of two different types of 51:115-50.
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Ricketts RM, Bench RW, Gugino CF, HilgersJJ,
Marsh JL, Vannier MW (1990) Three-dimensional Schulhof RJ (1979) Bioprogressive Therapy. (Rocky
imaging from CT scans for evaluation of patients Mountain Orthodontics: Denver, Colorado.)
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Meulen J, Mazzola RR (eds) Craniofacial Riedel RA (1974) A postretention evaluation. Angle
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Salzmann JA (1960) The research workshop on
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51:269-300. Salzmann JA (1972) Orthodontics in Daily Practice.
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Melsen B (1974) The cranial base. Acta Odont
Scand 32(suppl 62).
124
CHAPTER 5
Sources of Error in Lateral Cepbalometty

Vincenzo Macri and Athanasios E Athanasiou
NTRODUCTION clusion has to be drawn from cephalometric data, it

is equally important to consider both the validity
According to Moyers et al (1988), cephalometrics is and the reproducibility of the method used.
aradiographic technique for abstracting the human
head into a geometric scheme. Cephalometric radi
ography may be used: VALIDITY
• for gross inspection;
P to describe morphology and growth; Validity, or accuracy, is the extent to which - in the
|* to diagnose anomalies; absence of measurement error - the value obtained
• to forecast future relationships; represents the object of interest (Houston, 1983).
• to plan treatment; and Both what is being measured and the method of
• to evaluate treatment results. measurement have to be taken into account. Some
cephalometric landmarks and planes do not agree
Gross inspection does not require identification, with the anatomical structures they are meant to
tracing, or measurement of the various dentoskele- represent because they have been chosen for con
ialand soft tissue relationships, since it consists of venience of identification rather than on grounds of
a visual examination of the X-ray image only. All anatomic validity. Variations in skeletal structure
the other functions listed above are principally con can affect the identification of these landmarks, and
cerned with the identification of specific landmarks their inconsistency as reference points during
and with the calculation of the various angular and growth or treatment can be misleading.
linear variables that are described by means of these
landmarks. The last three functions require more
complex mathematical and statistical calculations REPRODUCIBILITY
orspecific reference planes for superimposition tech
niques. Reproducibility, or precision, is the closeness of suc
All these procedures are potentially affected by cessive measurements of the same object (Houston,
several sources of error whose influence can vary to 1983). If a certain measurement is persistently over
agreat extent. Unfortunately, many of these sources estimated or under-estimated, a systematic error or
of error are inter-related in such a way that a clear- bias is introduced. If no systematic error is present,
cut distinction cannot be easily made. However, in the cluster of observations will be randomly dis
| this chapter such a separation has been attempted tributed around the true value to express the
with the aim of better presenting the sources of error random error (McWilliams, 1983).
iincephalometry. The term reliability is used as a synonym for
Since cephalometry deals with geometric con- reproducibility, but it is sometimes also used in a
jstructions and calculations, it presupposes the accep- broader sense that encompasses both validity and
jtance of some conventions related to the type of reproducibility (Houston, 1983).
analysis chosen. Subsequently, if any consistent con
125
ERRORS O F C E P H A L O M E T R I C focus-film distance of more than 280 cm does not

MEASUREMENTS significantly alter the magnitude of the projection
error (Carlsson, 1967; Ahlqvist et al, 1986, 1988).
Cephalometric measurements on radiographic The use of angular rather than linear measurements
images are subject to errors that may be caused by: is a consistent way to eliminate the impact of mag-
• radiographic projection errors; r> nification (Adams, 1940), since angular measures
• errors within the measuring system; and remain constant regardless of the enlargement
• errors in landmark identification. factor.
Distortion
RADIOGRAPHIC PROJECTION ERRORS Distortion occurs because of different magnifica
tions between different planes. Although most of the
During the recording procedure, the object as landmarks used for cephalometric analysis are
imaged on a conventional radiographic film is sub located in the midsagittal plane, some landmarks
jected to magnification and distortion. and many structures that are useful for superim
■
posing radiographs are affected by distortion, owing

Magnification to their location in a different depth of field. In rhis
Magnification occurs because the X-ray beams are instance, both linear and angular measurements will
not parallel with all the points in the object to be be variously affected.
examined. The magnitude of enlargement is related Linear distances will be foreshortened, an effect
to the distances between the focus, the object, and that can be compensated for if the relative lateral
the film (Adams, 1940; Brodie, 1949; Hixon, 1960; displacement of the landmarks and their distance
Bjork and Solow, 1962; Salzmann, 1964). The use from the midsagittal plane are known. A combina
of long focus-object and short object-film distances tion of information from lateral and frontal films
has been recommended in order to minimize such has been proposed (Broadbcnt, 1931; Savaraetal,
projection errors (Franklin, 1952; Nawrath, 1961; 1966), but only a few landmarks can be located on
van Aken, 1963) (5.1, 5.2). However, although rel both projections.
atively long focus-film distances are favourable, a
5.1 Effect of focus-film distance on radio-

graphic magnification. (After Franklin, 1951
AMooe y
V
2h
*8 *"CDC
7 /■¥ y. /*Aa#'S/(0 0/j roe T/OM
J*f
'S 3S X
126
r Sources of Error in Lateral Cephalotnetry
Projected angular measurements (e.g. the gonial It is convenient, therefore, to average and trace
ein a lateral headplate) are distorted according as a single image those structures whose images are
r
to the laws of perspective (Slagsvold and Pedersen, doubled and exhibit an apparent asymmetry (e.g.
1977). Furthermore, landmarks and structures not the mandibular ramus and corpus, the pterygoid
situated in the midsagittal plane are usually bilat space, and the orbits). However, this type of tracing
eral, thus giving a dual image on the radiograph. is inadequate to describe a head that is truly asym
The problem of locating bilateral structures sub metrical (Grayson et al, 1984). In addition, in cases
jected to distortion can t o some extent be compen- of mild asymmetry it is difficult, using a lateral
sated for by recording the midpoints between these cephalogram, to differentiate between geometric dis
structures. %\atera\ structures m the symmetric Yicad" tortion and true subject asymmetry (Cook, 1980).
do not superimpose in a lateral cephalogram. The
Misalignment or tilting of the cephalometric com
fan of the X-ray beam expands as it passes through ponents (e.g. the focal spot), the cephalostat, and
the head, causing a divergence between the images t h e film with respect t o each other, a s well as rota
of all bilateral structures except those along the tions of the patient's head in any plane of space, will
central beam. introduce another factor of distortion (5.3).
5.2 Effect o f o b j e c t - f i l m distances o n

radiographic magnification and sharpness.
(After Franklin, 1952; reprinted w i t h per
mission.)
u&oeaAf'c raojicrtoM or e+stcr * wo** *M*C ruajecTfo" or OMJtcr *r

•^cMt'Sto &MTA**C*Z 0SOM SM.A*.
/.AM*** nA>mmtftCAr>o*/ or is**** SMf.
5.3 Directions of possible misalignments

of the patient's head. (After Ahlqvist e t al,
1986; reprinted w i t h permission.)
127
Orthodontic Cepkatometry
Malposition of the patient in the cephalostat ERRORS W I T H I N THE MEASURING

produces an asymmetric distortion for both linear SYSTEM
and angular measurements on lateral cephalograms
(Baumrind and Frantz, 1971b) (5.4). By using a In conventional cephalometry, the development of
mathejmatic model, however, Ahlqvist et al ( 1 9 8 3 , computerized equipment for electronic sampling of
1986) demonstrated that minor malpositions in the l a n d m a r k s has greatly speeded up data collection
cephalometric devices are of little importance for the and processing a n d has reduced the potential for
total projection error. The same model was applied h u m a n measuring errors. The first computerized
t o determine linear a n d angular distortion due to measuring devices were electromechanical and had
incorrect patient positioning (Ahlqvist et al, 1988). built-in sources for parallax and mechanical errors
The resulting projection error seemed in n o instance (Butcher a n d Stephens, 1 9 8 1 ; Cohen and Linney,
t o be of major concern, as angle distortion never 1984).
exceeded ± 0.5° for rotations of the head up to ± 5°. N o w d a y s , the general diffusion of digitizers and
Larger rotations of the head are unlikely, as they recording tablets has virtually eliminated these
would be obvious to the examiner (Spolyar, 1987). problems. The accuracy of the digitizer determines
In several clinical studies in which errors between the m i n i m u m measuring e r r o r possible with this
single tracings from duplicate radiographs were system. The errors related t o the recording proce
compared to errors arising from double tracings of dure have t w o c o m p o n e n t s : the precision with
single radiographs, the differences found were small which a marked point on the film or tracing can be
(Bjork, 1 9 4 7 ; Solow, 1966; M i t g a a r d et al, 1974; identified by the cross-hair of the recording device,
H o u s t o n et al, 1986). Therefore, if proper care in and the errors of the digitizing system (Eriksen and
obtaining radiographic records is taken, the errors Solow, 1991). An accuracy of 0.1 mm is desirable,
introduced during this phase can be regarded as neg without any distortion over the surface of the digi
ligible for r o u t i n e clinical purposes. In o r d e r to tizer (Houston, 1979).
control errors during radiographic projection, the Although errors of digitizers have been consid
relationships a m o n g the X-ray target, the head ered to be small, it has been shown that digitizers
holder, and the film must be fixed (Coben, 1979). may suffer from varying degrees of scaling errors
The metal markers in the ear-rods must be aligned, a n d fields of non-linearity (McWilliams, 1980;
and it is good practice t o include a metal scale of Kriksen a n d Solow, 1991). Eriksen and Solow
k n o w n length at t h e midsagittal plane to provide (1991) have described specific procedures for testing
permanent evidence of the enlargement of each radi and correcting the digitizers before any routine use
ograph (Houston, 1983). For special research appli in cephalometric research. Errors of scaling can be
cations, projection errors can be also reduced by a corrected by setting switches in the control unit of
c o m b i n a t i o n of stereo head films a n d t h e use of the digitizer or by scaling the incoming x—y co-ordi
osseous implants (Rune et al, 1977). nates by a software programme. Non-linearities can
be corrected by including the DXji and DYji
5.4 The effect of head rotation on the

value of an angle assumed to be measured
in the midsagittal plane. The angle
forehead-nose-chin appears progressively
more obtuse as the head rotates from the
true midsagittal plane. In addition, the
more acute the true angle is, the greater
the distortion will be. (After Baumrind and
Frantz. 1971b; reprinted with permission.)
128
Sources of Error in Lateral Cephatometry
latriccs in the digitizing programme and adjusting tracing of an indistinct structure might help in the
le recorded co-ordinates by the weighted mean of identification of a related landmark (e.g. tracing an
che DXji and DYji values of the four points that incisor's root might help in the identification of the
.'limit the square in which the recorded point is landmark incisor apex).
situated. Finally, weighting should depend on the There is no doubt that electronic plotting devices,
location of the recorded point within the square. which make repetitive measurements faster and less
If these requirements are met, measurements per tedious and which introduce facilities like error
formed by digitizer arejnore reliable than those checking routines, can greatly reduce the random
obtained with any manual device, owing to the cephalornetric errors.
superior accuracy of the digitizer (Richardson,
1981). Moreover, the use of a digitizer allows direct
registration of landmarks on the cephalogram, thus ERRORS IN LANDMARK IDENTIFICATION
eliminating the need for tracing procedures.
Whether this has removed a possible source of error Landmark identification errors are considered the
is still a matter of debate. major source of cephalornetric error (Bjork, 1947;
Richardson (1981) and Cohen (1984) claimed Hixon, 1956; Savara, 1966; Richardson, 1966,
lat direct observation on untraced lateral head- 1981; Carlsson, 1967; Baumrind and Frantz, 1971a;
iates resulted in an increased reliability in Sekiguchi and Savara et al, 1972; Gravely and
landmark location, though the differences compared Benzies, 1974; Mitgaard et al, 1974; Cohen, 1984).
paper tracings were not big and represented only Many factors are involved in this uncertainty. These
small part of the total error in landmark location. factors include:
)th authors traced only the landmarks and not the • the quality of the radiographic image;
latomic outlines. When these were traced • the precision of landmark definition and the
louston, 1982), the tracings sometimes showed a reproducibility of landmark location; and
lightly higher reproducibility, possibly because the • the operator and the registration procedure.
t)A'4*
**4*
Effect of focal spot size on radiographic sharpness. A ' and B' represent areas of radiographic penumbra with
sequent loss of sharpness. (After Franklin, 1952; reprinted with permission.)
129
Quality of the radiographic image the film-cassette system and the kV-level used. High
In principle, the quality of a radiograph is expressed kV values tend to level out any differences in radi
in terms of sharpness - blur and contrast - and noise ation absorption, thus reducing the difference in
(Rossmann, 1969; McWilliams and Welander, 1978; grey levels between various tissues. Noise refers to
Hurst et al, 1979; Broch et al, 1981; Kathopoulis, all factors that disturb the signal in a radiograph.
1989). It may be related to:
Sharpness is the subjective perception of the dis • the radiographic complexity of the region (i.e. the
tinctness of the boundaries of a structure; it is radiographic superimposition of anatomical
related to blur and contrast. structures situated in different depth planes) - this
Blur is the distance of the optical density change is known as noise of pattern, structure, or
between the boundaries of a structure and its sur anatomy; or
roundings (Haus, 1985). It results from three • receptor mottle - this is known as quantum noise.
factors, namely geometric unsharpness, receptor It depends on the sensibility and the number of
unsharpness, and motion unsharpness. radio-sensitive grains present in the film.
Geometric unsharpness is directly related to the
size of the focal spot (5.5) and to the focus-film In principle, structured noise can be reduced by the
distance. Receptor unsharpness depends on the use of cephalometric laminography (Ricketts, 1959),
physical properties of the film and the intensifying but in conventional cephalometry it is unavoidable.
screen. Combinations of fast films and rare earth These types of errors can be minimized by films
intensifying screens are used to reduce the radiation of high quality (Houston, 1983).
exposure, but produce images with poorer defini In recent years, the application of digital tech
tion. It is still a matter of controversy whether the nology to conventional radiography has changed the
loss of sharpness from this source results in signifi parameters of image quality by making it possible
cant differences in the reproducibility of landmark to process the image in order to enhance sharpness
identification (McWilliams and Welander, 1978; and contrast and to reduce noise. It has been argued
Stirrups, 1987). that the main advantage of digital processing may
Movement of the object, the tube, or the film be a reduction in radiation dose due to lower
during exposure results in image blur. By increasing exposure times (Wenzel, 1988). Furthermore, the
the current, it is possible to reduce the exposure contrast and density of a single underexposed image
time, thus reducing the effect of movement. Blur can be adjusted for several diagnostic tasks, thus
from scattered radiation can be reduced using a grid reducing the number of examinations. Jager et al
at the image receptor end. In clinical orthodontic (1989b) presented digital images in which resolu
practice, however, the major parameters that influ tion and the discrimination of anatomical structures
ence the sharpness of cephalograms are the focus- were improved after digital filtering. This improve
to-film distance (geometric unsharpness) and the ment was claimed to be particularly appreciable for
voltage capacity (kV) of the cephalometric equip underexposed radiographs.
ment (motion unsharpness).
Contrast is the magnitude of the optical density Precision of landmark definition and
differences between a structure and its surroundings. reproducibility of landmark location
It plays an important role in radiographic image A clear, unambiguous definition of the landmarks
quality. Increased contrast enhances the subjective chosen is of the utmost importance for cephalo
perception of sharpness, but excessive contrast leads metric reliability. Definitions such as 'the most
to loss of details, owing to blackening of regions of prominent' or 'the uppermost' should always be
low absorption and reverbering of regions of high accompanied by the reference plane that they are
absorption. The contrast is determined by: related to. If the conditions required to record some
• the tissue being examined; landmarks - e . g . Mips in repose', 'centric occlusion',
• the receptor; and or 'head posture' - are ambiguous or neglected, an
• the level of kV used. invalidation of the measurement involved can occur
(Wisth and Boe, 1975; Spolyar, 1987). As it has been
In clinical practice, the most important parameters pointed out by several investigators (Richardson,
influencing the contrast of cephalometric films are 1966; Baumrind and Frant?., 1971a; Broch et al,
130
Sources of Error in Lateral Cephalometry
[1981; Stabrun and Danielsen, 1982; Cohen, 1984; imposed structure. This may cause, for example, dif
I Miethke, 1989), some cephalometric landmarks can ficulty in accurately locating the cusps of posterior
I be located with more precision than others. teeth or the lower incisor apex (Miethke, 1989).
Geometrically constructed landmarks and land- Furthermore, the distribution of errors for many
marks identified as points of change between con landmarks is systematic and follows a typical
vexity and concavity often prove to be very pattern, some landmarks being more reliable in
unreliable. The radiographic complexity of the either the vertical or horizontal plane, depending on
'region also plays an important role, making some the topographic orientation of the anatomic struc
landmarks more difficult to identify. For these tures along which their identification is assessed
reasons, the validity of the use of some cephalo (Baumrind and Frantz, 1971a). The validity of indi
metric landmarks has often been questioned vidual landmarks will also depend on the use the
(Moorrees, 1953; Graber, 1954; Salzmann, 1964; orthodontist is making of them (e.g. some land
Richardson, 1966; Broch et al, 1981). Miethke marks are designed to assess angular measurements,
others to assess linear measurements).
! (1989) found that the landmarks that can be local
ized most exactly are incision superior incisal and Baumrind and Frantz (1971b) pointed out that
incision inferior incisal, with a value of the mean x the impact that errors in landmark location have on
and y standard deviations as polar co-ordinates of angular and linear cephalometric measurements is
0.26 mm and 0.28 mm respectively. A value of up a function of three variables:
to 2.0 mm was observed in the majority of the 33 1. The absolute magnitude of the error in landmark
landmarks in this study, which were, on this basis, location.
considered to be of acceptable reproducibility. 2. The relative magnitude or the linear distance
About 25% of the reference points showed a vari between the landmarks considered for that
ation amounting to more than 2.0 mm (Table 5.1). angular or linear measurement.
Anatomical porion and cephalometric landmarks on 3. The direction from which the line connecting the
the condvle cannot be located accurately and con- landmarks intercepts their envelope of error.
sistently on lateral cephalograms taken in the closed-
mouth position (Adenwalla et al, 1988). The envelope is the pattern of the total error distri
Landmarks located on structures that lie within bution. Since cephalometric landmarks have a non-
the confines of the skull have a greater likelihood of circular envelope of error, the average error
being confounded by noise from adjacent or super- introduced in linear measurements will be greater if
Table 5. \ Value of vector V (the expression of the mean x and y

standard deviations as polar co-ordinates) in mm for all assessed
cephalometric landmarks as expression of the precision in
localization. A smaller value for vector V corresponds to greater
precision in definition of the landmark (Miethke. 1989).
131
the line segment connecting them to another point location were generally the same. An exception were
intersects the wider part of the envelope. For measures of face height, which were more reliable
example, a greater error is expected when point A for hard tissues. When analysing cephalometric
is used to assess the inclination of the maxillary data, errors in landmark location for points or lines
plane rather than to assess the maxillary prog- common to more measurements can generate mis
nathism, as the direction of the former line is hori leading topographic correlations, which may
zontal to and thus intersects the envelope of error in obscure or exaggerate a true biologic correlation
its broader side (5.6). Therefore, the various (Bjork and Solow, 1962; Solow, 1966; Houston,
cephalometric measurements used have different 1983) (5.7).
reliability since their landmarks, angular measure Errors in landmark identification can be reduced
ments, or linear measurements are influenced by if measurements are replicated and their values
errors of different origin and whose magnitude averaged. Consecutive evaluation of one cephalo-
greatly varies. gram at random showed that the localization of a
When the reliability of cephalometric soft tissue landmark is more exact the second time than at the
measurements was studied by analysing compara first judgement (Miethke, 1989). The more the
ble hard and soft tissue measures (Wisth and Boe, replications, the smaller the impact of random error
1975), it was found that the errors of landmark on the total error becomes. There is, however, a
5.6 Effect of a non-circular envelope of landmark error on the

. t
i c o m p u t a t i o n of values o f a r e p r e s e n t a t i t i v e m e a s u r e . The
i scattergram of e r r o r for 100 estimates of nasion is shown, with
i
i boxes indicating zones I, 2, and 3 standard deviations of the
i estimating e r r o r in the x and y directions taken separately. It may
I
be observed that the errors are greater in the vertical direction
/
iI than in the horizontal d i r e c t i o n . For this reason, other factors
being equal, a greater e r r o r will be introduced in the computation
•< of the angle sella-nasion-pogonion by the line segment from sella
■
(A) than by the line segment from pogonion (B). (After Baumrind
J '
A and Frantz, 1971a; reprinted with permission.)
Lm
i
• 1 •
ID
5.7 Topographic c o r r e l a t i o n can arise

through random errors in the location of a
point or line common t o both
m e a s u r e m e n t s . For e x a m p l e , in (a), if
repeated measurements are made of A and
B, the dividing line between them varying at
r a n d o m , t h e r e w i l l be a negative
correlation between their lenghts. In (b).
t w o angular measures share a common line
and random e r r o r s in its orientation will
lead t o a negative c o r r e l a t i o n between
t h e m . O t h e r p o s i t i v e and negative
topographic correlations can arise in this
manner. (After H o u s t o n , 1983; reprinted
w i t h permission.)
132
Sources of Error in Lateral Cepbalometry
practical limit to repeated assessment of cephalo- Another kind of bias can be introduced because
grams, especially for clinical routine. Even for the of subconscious expectations of the operator when
purpose of scientific research, if cross-sectional or assessing the outcome of the scientific research (i.e.
serial measurements from two groups must be the outcome of different treatment results).
compared, duplicate measurements are sufficient Randomization of record measurements or double
(Miethke, 1989). More replications should instead blind experimental designs can be used for reducing
be performed for the evaluation of individual such bias.
changes (Baumrind and Frantz, 1971b; Gravely and When serial records are being analysed, it has
Benzies, 1974; Houston, 1983). been suggested that all the records of one patient
For specific landmarks, the application of alter should be traced on the same occasion (Houston,
native techniques of radiological registrations can 1983). This minimizes the error variance within
minimize errors in landmark identification. For individual observers, although it increases the risk
■example, if the mandibular condyle is to be used as of bias. Since serial tracing must maintain precise
an important landmark in cephalometric studies, an common landmarks in regions without change
open-mouth cephalogram should be taken. during treatment or growth, landmark location in
Subsequent superimposition on the respective such regions can be identified in one of the cephalo-
! cephalogram in the centric occlusion position can grams and transferred to the other cephalograms of
provide the most accurate and reliable measurement the patient by use of templates of the corresponding
(Adenwalla et al, 1988). Also, if porion is defined structure (e.g. incisal edges of maxillary and
as a machine point rather than an anatomical point, mandibular incisors) (Gjorup and Athanasiou,
higher reliability should be anticipated (Baumrind 1991).
and Frantz, 1971a). After collection, cephalometric measurements
should be checked for wild values (Houston, 1983).
The operator and t h e registration procedure These values can be expressions of normal variation,
Several studies have pointed out that operator's but sometimes can be attributed to incorrect identi
alertness and training and his or her working fication of a landmark or misreading of an instru
conditions affect the magnitude of the ment.
cephalometric error (Kvam and Krogstad, 1972;
Gravely and Benzies, 1974; Houston, 1983). These
I parameters influence landmark identification in a ERRORS IN GROWTH PREDICTION

fashion directly related to the difficulty of A N D SUPERIMPOSITION
identifying each individual landmark. In TECHNIQUES
cephalometric studies, the error level, specific to the
operator, has to be established, if any meaningful Growth prediction has been attempted by several
conclusion is to be drawn from the data presented. methods. Growth prediction is quite difficult for a
The most important contributions to improve number of reasons (Ari-Viro and Wisth, 1983).
ment in landmark identification are experience and Among these factors are:
calibration (Houston, 1983). In studies that • the wide range of morphological differences;
compare two groups of radiographs, the operator • the varying rates and directions during the
can introduce different types of systematic error (or growth period;
bias) depending on the design of the study. One type • the varying influence of modifying environmen
of operator bias is the operator's variability, which tal factors;
involves both inter-observer variability (the dis • the variation in the timing of the different areas
agreement among observers for the Identification of of active growth; and
a particular landmark) and intra-observer variabil • the lack of correlation between the size of the
ity (the disagreement within the same observer over facial structures at an early age and the ultimate
a period of time owing to changes in his or her iden adult size.
tification procedure). A good method to reduce this
error consists of calibration and periodical recali- Rakosi (1982) has given some good examples of the
bration tests to establish specific confidence limits sources of error in growth prediction, including:
of reproducibility for each observer (Houston, 1983; • variable growth rate in regional growth sites;
Houston etal, 1986).
133
Orthodontic Cephalotnetry
• g r o w t h pattern not being fully taken into lar a n d maxillary g r o w t h r o t a t i o n s (Bjork and
account; and Skieller, 1 9 7 2 ; Skieller et al, 1984). However, a
• the relationship of form and function. clinical test t o determine the effectiveness of a
n u m b e r of experienced clinicians at predicting
Variable g r o w t h r a t e in regional g r o w t h s i t e s m a n d i b u l a r rotations showed that, independently
The mean annual rate of increase in the base of the of the prediction method used, no judge performed
maxilla between the ages of eight and 14 is approx significantly better t h a n chance (Baumrind et al,
imately 0.8 m m , c o m p a r e d to 1.9 m m in the 1984). The method of structural growth prediction
m a n d i b u l a r base. During t h e same period, the introduced by Bjork (1963) has been investigated in
growth ratio of the S - N length t o the m a n d i b u l a r another study that used t w o sets of lateral cephalo-
base ranges from 1:1.35 to 1:1.65 and that of S-Ar grams of 4 2 children, taken four years apart before
t o A r - G o is approximately 1:1.3. and after the pubertal growth period (Ari-Viro and
Wisth, 1983). T h e r e was n o absolute correlation
Growth pattern not being fully taken into between the scores for the different criteria and
account mandibular growth rotation during the four years
M a n y methods d o not include consideration of the of observation.
growth p a t t e r n , and patients a r e assessed only in According to the authors, this does not mean that
relation to a population mean. Usually growth rates the method is useless, but in cases showing relatively
vary quite considerably for different growth types. small rotational changes the method does not work
Generally speaking, horizontal growth changes are well. In this investigation, n o study of the structur
more predictable than vertical changes. al characteristics was performed in cases showing
extreme anterior or posterior g r o w t h rotation.
T h e r e l a t i o n s h i p of f o r m a n d function Therefore, the main error in growth prediction pro
T h e inter-relationship of form a n d function is n o t cedures is the lack of validity of any m e t h o d until
taken i n t o consideration. For example, soft tissue now proposed, when it comes to prediction of the
influences in a patient with m a n d i b u l a r retrog- individual. In the light of these results, it is even
nathism can alter a tendency for compensatory pro- doubtful if cephalometric films contain enough
clination of the lower incisors to a dysplastic information a b o u t future growth to ever be of pre
retroclination (Melsen and Athanasiou, 1987). dictive value.
The simplest method of prediction assumes that

growth will take place as a linear expansion along LONGITUDINAL CRANIOFACIAL
the long axis of the structures being examined and ANALYSIS
that its a m o u n t is quantified as averaged growth
increments added progressively through time Longitudinal craniofacial analysis is based on super-
(Johnston, 1975; Popovich and T h o m p s o n , 1977). imposition procedures that vary according t o struc
The major limitation of this method is that individ tures used as references within the skull. A number
ual variability is not taken into account (Greenberg of m e t h o d s for growth analysis have been devel
and J o h n s t o n , 1975; Schulhof and Bagha, 1975). oped, based on axiomatic rules for superimposition
Individualized prediction has been attempted by on selected reference points and lines, including
analysing the existing facial pattern. However, the cranial base superimposition on N - S , N-Ba,
relationship of existing facial dimensions and of Ptm-vertical, basion-horizontal, Bolton-nasion line,
previous growth changes to future growth has not maxillary superimposition on P N S - A N S , and
been found to be of predictive value (Bjork and mandibular superimposition on mandibular plane,
Palling, 1 9 5 5 ; Harvold, 1 9 6 3 ; H i x o n , 1972) with XI point, and symphysis (Broadbent et al, 1975;
some exceptions in children with extreme skeletal Ricketts et al, 1 9 7 9 ; Bjork and Skieller, 1983;
patterns (Schulhof et al, 1977; N a n d a , 1988). Baumrind et al, 1 9 8 3 ; C o b e n , 1 9 8 6 ; Movers et al,
Prediction of growth direction, particularly for 1988).
m a n d i b u l a r r o t a t i o n , has also been attempted in Any variation due to remodelling processes that
implant studies analysing certain structural features have affected the reference structures can dramati
(Bjork, 1968), a n d a qualitative relationship has cally change the o u t c o m e of the superimposition
been described between these features and mandibu and lead to erroneous conclusions about the vectors
134
of growth. Therefore, it is important to choose struc ing pin holes, the blink method, or the subtraction
tures subjected to as little remodelling change as technique. When tested, however, all these methods
possible in order to ensure the validity of the meth showed an appreciable error and none of them was
od. In the absence of implants to be used as refer significantly more accurate than the others
ences, some structures of the cranial base have been (Houston and Lee, 1985).
found to be stable through time (Melsen, 1974) (5,8). A study by Fisker (1979) evaluated the repro
The reproducibility of the superimposition along ducibility of superimpositions on different cranial
the chosen reference structures is another source of structures. Superimposition on structures in the
error (5.9). The precision of tracing superimposi- cranial base proved to have the greatest repro
rions for different reference planes and lines has ducibility. Least reliable was the superimposition on
been found to be very unsatisfactory (Baumrind et zygomatic process. An increase in the interval
al, 1976); precision depends also on the amount of between the recording of the head films in the same
time between the films to be superimposed series appeared to lead to an increase in the error of
(Pancherz and Hansen, 1984). the method when orientating on the zygomatic
Regardless of the reference planes used, several process, the palatal structures and the mandible. The
techniques have been claimed to improve the repro expediency of using repeated separate measurements
ducibility of superimposition, such as best fit direct of the same dimension on the cephalograms was
supermimposition, tracing superimposition, punch- also concluded by the same investigation.
1
//?c _rr^^
r ^ -j"1
s
-A**
'^c
$
vt :
i
v\
I
;
j
\
:<=r—
1/
J ^* ^w A*"
l * ^L
t *|
'•'
I '** v
* * ■
»* J
* f
■* rr
* f
*
■
*
*
*
1
II
'
ft
5.8 Diagrammatic representation of g r o w t h remodelling in the

cranial base. The variation in the age at which g r o w t h ceases in the
different segments is not indicated. (After Melsen. 1974; reprinted
with permission.)
5.9 Errors in superimposition that are due either t o displacement

and remodelling o r t o p o o r reproducibility of the reference points
o r structures may give a false impression of facial g r o w t h . A small
rotation at sella can produce an evident displacement at Menton.
(After Houston and Lee. 1985; reprinted w i t h permission.)
135
CONCLUSION REFERENCES
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140
CHAPTER 6
Posteroanterior (Frontal) Cepbalometry

Atbanasios E Athanasiou and Aart JW Van der Meij
INTRODUCTION TECHNICAL ASPECTS
Malocclusions and dentofacial deformities consti
tute three-dimensional conditions or pathologies. CEPHALOMETRIC SET-UP
Although all orthodontic patients deserve an
equally comprehensive three-dimensional diagnos In order to produce a posteroanterior cephalogram,
tic examination, assessment of posteroanterior and the same equipment that is used for lateral cephalo
basilar cephalometric views are of particular impor metric projections, as described in chapter 1, is
tance in cases of dentoalveolar and facial asymme utilized. The basic apparatus consists of a head-
tries, dental and skeletal crossbites, and functional holder or cephalostat, an X-ray source, and a
mandibular displacements. The transverse dimen cassette holder containing the film.
sion of a patient who seeks orthodontic treatment Different ways of producing cephalograms by
requires a diagnostic protocol that includes sys means of different set-ups and patient positioning
tematic evaluation of: in the cephalostat have been described and are still
• the soft tissues, by means of clinical examination used. In all instances, the patient is in an upright
and photography; position, either standing or sitting, and is facing the
• the dentofacial skeleton, by means of pos film, because this provides the best quality rendi
teroanterior cephalograms and submental vertex tion of the facial structures that are of primary
X-rays; and interest in orthodontics.
• the dentition, by means of dental casts, occluso- In all techniques, it is of paramount importance
grams and sometimes occlusal X-rays. that the connection between the X-ray source and
the cassette holder containing the film is rigid, in
Since facial asymmetries and crossbites are very order to maintain a constant relationship of the X-
often associated with dysfunction of the stomatog- ray beam perpendicular to the surface of the
nathic system, an important component of the dif cassette (Manson-Hing, 1985).
ferential diagnosis should be the assessment of The initial unit described by Broadbent (1931)
functional and structural status of the patient by consisted of a set-up in which two X-ray sources
means of history, clinical and instrumental func with two cassettes were simultaneously used, so
tional evaluation, occlusal splints, imaging of the that lateral and frontal cephalograms were taken at
tempromandibular joint, and laboratory tests the same time. In this technique, the patient was
(Athanasiou, 1993). placed with the Frankfort horizontal plane parallel
Since the advent of cephalometric radiography, to the floor. The X-ray source exposing the cassette
orthodontists have focused on the lateral cephalo for the posteroanterior cephalogram was 5 feet
grams as their primary source of skeletal and den (152.4 cm) away from the earpost axis, behind the
toalveolar data; however, posteroanterior patient, and the central X-ray beam passed at the
cephalometric projections and relevant analyses level of the Frankfort horizontal plane and at a 90°
constitute an important adjunct for qualitative and angle to the beam of the lateral cephalogram.
quantitative evaluation of the dentofacial region.
141
Although precise three-dimensional evaluations N a t u r a l h e a d position

are possible using this technique, it has now been Natural head position is a standardized orientation
almost abandoned since it requires a rather large of the head, which is readily assumed by focusing
equipment with two X-ray sources. on a distant point at eye level (Moorrees, 1985).
Modern equipment uses one X-ray source. Reproducibility of natural head position, assessed
Therefore, following lateral cephalometric regis as the error of a single observation, has been found
tration, the patient must be repositioned if a pos- to be close to 2°, which supports its use in
teroanterior cephalogram has to be produced. A cephalometry (Lundstrom and Lundstrom, 1992).
r j headholder orêphalostat that can_be rotated 90°
is used, so that the central X-ray beam penetrates
The natural head position cephalometric regis
tration has been described in detail in other chapters
the skull of the patient in a posteroanterior direc of this book. If a posteroanterior registration is
tion and bisects the transmeatal axis perpendicu taken in the natural head position, the ear-rods are
larly. The standard distance from X-ray source to placed directly in front of the tragus so that they
patient is 5 feet (152.4 cm). For the posteroanteri lightly contact the skin, thus establishing bilateral
or projection the distance is measured to the earpost head support in the transverse plane (6.2). The radi-
axis. ographic image of ;i metallic chain, hanging on one
side of the film cassette, defines the true vertical
Fixed head position plane on the radiograph.
In the most commonly used technique, the patient In using the natural head position for pos
is fixed in the headholder with the use of two ear- teroanterior cephalometric registrations, some prac
rods, and the patient's head rests on the uppermost tical problems are encountered. The patient's head
side of the rods, which are inserted into the ear is facing the cassette, which makes it difficult for
holes (6.1). Care must be taken that the Frankfort the patient to look into a mirror to register natural
horizontal relationship of the head with the floor is head position (Solow and Tallgren, 1971).
not altered during this procedure. This reproduc Furthermore, space problems in some X-ray equip
tion of the head position in the cephalostat is crucial ment make it impossible to place a nosepiece in
because, when the head is tilted, all vertical dimen front of nasion, lightly touching the skin, as is some
sions measured change. Maintaining the identical times done to establish support in the vertical plane
horizontal orientation from lateral to posteroan (Viazis, 1991).
terior projections is critical when comparative
measures are made from one to the other (Movers
etal, 1988).
6.1 Fixed head position - the patient is 6.2. Natural head position - the ear-rods
fixed in a headholder with the use of the are placed directly in front of the tragus,
two ear-rods and the head rests on the lightly touching the skin, thus establishing
uppermost side of the rods, which are bilateral head support in the transverse
inserted into the ear holes. (Photo: Lars plane. (Photo: Lars Kruse)
Kruse)
142
Posteroanterior (Frontal) Cephalometry
Other techniques o f head positioning ANATOMY

According to Chierici (1981), the patient's head
should be positioned with the tip of the nose and Many anatomical structures located in the anterior,
forehead lightly touching the cassette holder (6.3). middle, and posterior areas of the skull are usually
The author claims that this technique enables better projected in a posteroanterior cephalogram. The
evaluation of patients with craniofacial anomalies anatomical structures of the skull seen from the
that require special attention to the upper face. front are shown in 6.5, and those seen from behind
Faber (1985) has suggested that, in cases of sus are shown in 6.6.
pected significant mandibular displacement, the
posteroanterior cephalogram should be taken with
the mouth of the patient slightly opened (6.4). In RADIOGRAPHIC ANATOMY
this way a differential diagnosis between function
al mandibular displacement and dentoskeletal facial The various structures of the skull that can be seen
asymmetry can be made. in a posteroanterior cephalogram are shown in 6.7
and 6.8. In these two figures, an excellent visual
Exposure conditions and considerations ization of the structures that can be traced has been
Film exposure depends on several factors, includ achieved by wiring the two skulls with fine lead fuse
ing the speed of the film, the speed of the screens, wire. The structures have been labelled alphabeti
the tube-to-film distance, the size of the patient's cally (Broadbent et al, 1975).
head, the milliamperage and kilovoltage used in
generating the X-ray beam, and the film exposure
time (Manson-Hing, 1985). More exposure is nec
essary for posteroanterior cephalograms than for
lateral views (Enlow, 1982).
M\
: ! Tracing of a posteroanterior cephalogram taken w i t h the 6.4 H e a d p o s i t i o n i n g in cases o f s i g n i f i c a n t m a n d i b u l a r

[dent's head positioned w i t h the tip of the nose arid forehead displacement - the cephalogram is taken with the mouth of the
tehtly touching t h e c a s s e t t e h o l d e r . ( A f t e r C h i e r i c i , 1 9 8 1 ; p a t i e n t slightly o p e n e d . ( A f t e r Faber, 1985; r e p r i n t e d w i t h
(printed with permission.) permission.)
143
6.6 The skull seen from behind presents the following anatomical
structures. (After McMinn etal, 1981; reprinted with permission.)
6.5 The skull seen from the f r o n t presents the following

1 Sagittal suture
anatomical structures. (After McMinn et al, 1981; reprinted with
2 Parietal foramen
permission.)
3 Lambda
4 Lambdoid suture
1 Frontal bone 18 Anterior nasal spine
5 Parietal bone
2 Glabella 19 Nasal septum
6 Parietal tuberosity
3 Nasion 20 Inferior nasal concha
7 Temporal bone
4 Superciliary arch 21 Mastoid process
8 Mastoid process
5 Frontal notch 22 Zygomaticomaxillary
9 Squamous part of occipital bone
6 Supraorbital foramen suture
10 External occipital protuberance (inion)
7 Lesser wing of sphenoid 23 Infraorbital margin
11 Supreme nuchal line
bone 24 Marginal tubercle
12 Superior nuchal line
8 Superior orbital fissure 25 Frontozygomatic suture
13 Inferior nuchal line
9 Greater wing of sphenoid 26 Supraorbital margin
14 Body of the mandible
bone 27 Orbital part of frontal bone
15 Angle of the mandible
10 Zygomatic bone 28 Optic canal
16 Ramus of the mandible
11 Inferior orbital fissure 29 Posterior lacrimal crest
17 Occi pi to mastoid suture
12 Infraorbital foramen 30 Fossa for lacrimal sac
18 Pari etc mastoid suture
13 Maxilla 31 Anterior lacrimal crest
14 Mandibular ramus 32 Frontal process of maxilla
15 Body of the mandible 33 Nasal bone
16 Mental foramen o f the 34 Frontonasal suture
mandible 35 Frontomaxillary suture
17 Mental protuberance of the
mandible
144
6.7 and 6.8 Posteroanterior cephalogram of a skull, wired, and L - Zygomatic arch t o key ridge; inferior surfaces of malar bone,
alphabetically labelled in order t o describe structures that can be maxilla, and key ridge
traced. The following structures are identified. (After Broadbent M - Mastoid process
etal. 1975; reprinted w i t h permission.) N - Occipital bone: inferior surface of jugular process, condyles,
A-Crista galli and anterior margin of foramen magnum
8-Nasofrontal suture: external surface O - Occipital bone: posterior b o r d e r of foramen magnum and
C - Orbital roof: most superior area of inferior surface of orbital most inferior area of lateral part
plate of frontal bone P - Occipital bone: superior surface of area of greatest depth in
D - Orbit: superior b o r d e r (frontal bone); lateral b o r d e r posterior fossa (fossa of cerebellum)
(zygoma); inferior border (zygoma and maxillary bones) Q - Occipital bone: cross-section of border of foramen posterior
E- Lesser wing of sphenoid bone: anterior clinoid process t o left occipital condyle
F - Planum of sphenoid bone: across planum and down through R - P o s t e r i o r nasal a p e r t u r e (choana): vomer. s p h e n o i d , and
optic foramen palatine bones; medial pterygoid plate of sphenoid; and horizontal
G - Petrous portion of temporal bone: superior surface part of palatine bone
H - Greater w i n g of s p h e n o i d b o n e : t e m p o r a l surface and S - Sphenoid bone (cross-section): f l o o r of pituitary fossa through
infratemporal crest foramen lacerum across inferior surface of body of sphenoid bone
I - Maxilla: infratemporal surface d o w n t o and including alveolar between vomer bone and basilar part of occipital bone
process in molar area T A n t e r i o r nasal aperture: nasal bone and maxilla
J - Lateral ptcrygoid plate and greater wing of sphenoid bone; U - Mandible, condyle, neck, lateral border of ramus, and inferior
infratemporal fossa and crest border of body of mandible
K-Zygomatic arch; superior surface of the zygomatic process of V — C o r o n o i d process and mandibular notch
temporal and malar bones and cross-section of zygomatic process W - Ramus: medial surface of posterior part of ramus
of temporal bone at greatest bizygomatic w i d t h
145
.
Tracing suggestions patient (i.e. the patient's right should be on the

Before tracing the various skeletal and dental struc examiner's left). The tracing should include most of
tures of a posteroanterior cephalogram, the exami the important structures of the upper, middle, and
ner must ensure that the head position and the lower anterior face as well as of the posterior face.
intermaxillary occlusal relationships that appear in By including relevant structures, which will be pre
the X-ray do not differ significantly from those sented in this chapter, the tracing should allow the
identified during the clinical or photographic eval overall qualitative assessment of the morphology,
uation of the patient or those found in the analysis size, and harmony of the skull.
of dental casts. Any significant deviation between During the tracing of the posteroanterior cephalo
them may be due to registration errors in one or gram, it is essential to bear in mind where the struc
more of these diagnostic modalities. tures have been identified in the current lateral
Another important step before tracing commences cephalogram of the same patient. In this way, a
is to examine the posteroanterior cephalogram in more meaningful assessment of the information
order to exclude the possibility of pathology of the gathered from both the posteroanterior and the
hard and soft tissues involved (see Chapter 8). lateral X-rays can be achieved. A method for accu
The tracing of the posteroanterior cephalogram rately relating the lateral to the posteroanterior
should be carried out by placing the cephalogram cephalogram by using the Bolton Orientator has been
in front of the examiner as if he were looking at the developed and described by Broadbent et al (1975).
6.9 Structures that should be included in the

tracing of a posteroanterior cephalogram. The
numbers in the diagram refer to the descrip
tions in the text.
146
The tracing of the posteroanterior cephalogram cephalogram, it can nevertheless provide useful
may begin with the midline structures seen in the information and complement our diagnostic tools.
lateral cephalogram and should include the occip Some of the functions of the posteroanterior
ital, parietal, frontal, and nasal bones, the maxilla, cephalometry extend beyond the traditional appli
the sphenoid bone, and the symphysis of the cations of determining breadth and symmetry.
mandible (Broadbenr et al, 1975).
Furthermore, the authors of this chapter suggest Gross inspection
that the following structures should be included in Gross inspection of a posteroanterior cephalogram
the tracing of the posteroanterior cephalogram. The can provide useful information concerning overall
numbers refer to the diagram of 6.9. Other struc morphology, shape, and size of the skull, bone
tures may be added, depending on the needs of the density, suture morphology, and possible premature
examiner. synostosis. Furthermore, it can contribute to the
1. External peripheral cranial bone surfaces. detection of pathology of the hard and soft tissues
2. Mastoid processes. (see 6.10).
3. Occipital condyles.
4. Nasal septum, crista gaHi, and floor of the Description and comparison
nose. Description of the skull by means of a posteroan
5. Orbital outline and inferior surface of the terior cephalogram can be accomplished by com
orbital plate of the frontal bone. parison with other patients or with existing
6. Oblique line formed by the external surface of appropriate norms (Solow, 1966; Wei, 1970;
the greater wing of the sphenoid bone in the Ricketts et al, 1972; Broadbent et al, 1975;
area of the temporal fossa. Ingerslev and Solow, 1975; Svanholt and Solow,
7. Superior surface of the petrous portion of the 1977; Costaras et al, 1982; Droschl, 1984; xMoyers
temporal bone. et al, 1988; Athanasiou et al, 1991; Athanasiou et
8. Lateral surface of the frontosphenoid process al, 1992).
of the zygoma and the zygomatic arch, includ
ing the key ridge. Diagnosis
9. Cross-section of the zygomatic arch. Meaningful diagnostic information can be collect
10. Infratemporal surface of the maxilla in the ed from posteroanterior cephalograms by several
area of the tuberositv. reliable methods and analyses. The diagnostic
11. Body and rami, coronoid processes, and purpose of the posteroanterior cephalogram is to
condyles of the mandible, when visible. analyse the nature and origin of the problem, thus
12. As many dental units as possible. providing the possibility of quantification and clas
sification.
POSTEROANTERIOR T r e a t m e n t planning
CEPHALOMETRIC L A N D M A R K S Some of the diagnostic information that can be
gathered from a posteroanterior cephalogram after
Several cephalometric analyses have been proposed appropriate elaboration and analysis should be
since posteroanterior cephalometry was introduced. valuable enough to be used to produce a compre
These analyses use various landmarks. An attempt hensive and precise treatment plan with regard to
for <m almost all-inclusive presentation of these the specific orthodontic, orthopaedic, or surgical
landmarks, together with their description, has been treatment goals for the individual patient.
made in 6.10.
G r o w t h assessment and evaluation o f
t r e a t m e n t results
PURPOSES O F P O S T E R O A N T E R I O R Growth assessment by means of posteroanterior
CEPHALOMETRY cephalometry is difficult but it is possible. The main
problems are related to the absence of well-defined,
Although superimposition of several structures stable (or relatively stable) structures for the super-
makes interpretation of a posteroanterior cephalo imposition of the subsequent cephalometric tracings,
gram more difficult than interpretation of a lateral and to the difficulties in obtaining consecutive
147
6.10 Definitions of posteroanterior cephalometric landmarks. The landmarks are presented w i t h their most usual names.
ag - antegonion - the highest point in the antegonia/ notch (left and right)
ans — anterior nasal spine
cd - condylar - the most superior point of the condylar head (left and right)
c o r - coronoid — the most superior point of the coronoid process (left and right)
i i f - incision inferior frontale - the midpoint between the mandibular central incisors at the level of the incisal edges
isf - incision superior frontale - the midpoint between the maxillary central incisors at the level of the incisal edges
Ipa - lateral piriform aperture - the most lateral aspect of the piriform aperture (left and right)
lo - latero-orbitale - the intersection of the lateral orbital contour w i t h the innominate line (left and right)
m - mandibular midpoint - located by projecting the mental spine o n the lower mandibular border, perpendicular t o the line ag-ag
Im - mandibular molar - the most prominent lateral point on the buccal surface of the second deciduous o r first permanent mandibular
molar (left and right)
ma - mastoid - the lowest point of the mastoid process (left and right)
mx - maxillare - the intersection o f the lateral contour o f the maxillary alveolar process and the l o w e r c o n t o u r o f the maxillozygomatic
process of the maxilla (left and right)
um - maxillary molar - the most prominent lateral point on the buccal surface of the second deciduous o r first permanent maxillary
molar (left and right)
m o - medio-orbitale - the point o n the medial orbital margin that is closest t o the median plane (left and right)
mf - mental foramen - the centre of the mental foramen (left and right)
om - orbital midpoint - the projection on the line lo-lo of the top of the nasal septum at the base of the crista galli
za - point zygomatic arch - point at the most lateral border of the centre of the zygomatic arch (left and right)
tns - t o p nasal septum - the highest point on the superior aspect of the nasal septum
mzmf - zygomatic ofrontal medial suture point-in - point at the medial margin of the zygomaticofrontal suture (left and right)
Izmf - zygomaticofrontal lateral suture point-out - point at the lateral margin o f the zygomaticofrontal suture (left and right)
148
cephalograms in a standardized manner with regard left-sided and right-sided as well as upper and lower
to head posture and skull enlargement. face, can be examined concerning their vertical
In patients who are not growing, evaluation of dimension, position and proportionality. The
treatment results can be accomplished by superim analysis proposed by Grummons and Kappeyne van
posing the tracings of the subsequent posteroante de Coppello (1987) contains quantitative assess
rior cephalograms on the external peripheral cranial ment of vertical dimensions and proportions.
bone outline or on any of the reference horizontal Vertical asymmetry can be observed readily in a
planes whose structures have not been influenced posteroanterior cephalogram by connecting bilat
by the specific treatment. The cephalograms should eral structures or landmarks, by drawing the trans
betaken at different time intervals in a standard verse planes, and by observing their relative
ized manner with regard to head posture and mag orientation (Sollar, 1947; Proffit, 1991).
nification. Since the primary indication for obtaining a pos
Assessment of growth and treatment results can teroanterior cephalomctric film is the presence of
be done without superimposing the different facial asymmetry (Proffit, 1991), many analyses
cephalograms or tracings. Critical interpretation of contain variables and measurements of the trans
the characteristics and relationships of the various verse dimension. After establishing the midsaggital
craniofacial structures, or comparison of the plane, linear measurements, angular measurements,
various measurements, can provide significant and proportional measurements can be made in
information concerning changes that took place order to evaluate the severity and degree of asym
during the period of observation. metry or transverse deficiency (Ricketts et al, 1972;
Svanholt and Solow, 1977; Moyers et al, 1988;
Athanasiou et al, 1992). Relating the midline land
POSTEROANTERIOR marks to the midsagittal plane will provide a qual
CEPHALOMETRIC ANALYSES itative evaluation to help clarify the source of the
asymmetry. Vertical planes constructed through the
angles of the mandible and the outer borders of the
AIMS AND MEANS zygomatic arch can also highlight asymmetry in the
position of these structures (Proffit, 1991).
Most of the posteroanterior cephalomctric analyses Landmarks and variables that can be identified
described in the literature are quantitative, and they on coronal planes of different depths in the same
evaluate the craniofacial skeleton by means of posteroanterior cephalogram can provide useful in
linear absolute measurements of: formation concerning the vertical, transverse, and
• width or height (Solow, 1966; Ricketts et al, sagittal dimensions of the craniofacial skeleton. The
1972; Ingerslev and Solow, 1975; Movers et al, multiplane analysis developed by Grayson et al
1988; Nakasima and Ichinose, 1984; Grummons (1983) is the best and most complete method in this
and Kappeyne van de Coppello, 1987; category.
Athanasiou et al, 1992);
• angles (Ricketts et al, 1972; Svanholt and Solow,
1977; Droschl, 1984; Grummons and Kappeyne LIMITATIONS
vande Coppello, 1987; Athanasiou et al, 1992);
• ratios (Costaras et al, 1982; Grummons and Measurements on posteroanterior cephalograms,
Kappeyne van de Coppello, 1987; Athanasiou et like those on lateral cephalograms, are subject to
al, 1992); and errors that may be related to the X-ray projection,
• volumetric comparison (Grummons and the measuring system, or the identification of land
Kappeyne van de Coppello, 1987). marks.
It is possible to produce linear measurements on
The different structures of the craniofacial complex the posteroanterior cephalometric film, but precise
can also be analysed using qualitative methods measurements of details are likely to be misleading.
(Sollar, 1947; Grayson et al, 1983; Proffit, 1991). There is a chance that the apparent distance will be
A posteroanterior cephalogram can be analysed affected by a tilt of the head in the headholder, as
so that the vertical, transverse, and sagittal dimen this is more difficult to control in posteroanterior
sions can be evaluated. Different structures, both than in lateral cephalograms (Proffit, 1991). For the
149
same technical reason, angular measurements can METHODS O F ANALYSES

also be influenced in an uncontrolled manner.
Cephalometric variables that describe width are Ricketts analysis
least affected by postural alterations of the head This analysis incorporates the following measure
during registrations. According to an earlier inves ments (6.11) whose clinical norms are presented in
tigation concerning the geometric changes on the Table 6.1 (Ricketts et al, 1972).
posteroanterior headfilm in the various head posi • nasal cavity width - measured from NC to NC
tions, a change of ± 10° of up—down movement or (widest points in nasal capsule). In clinical diag
right-left rotation is less than the method error and nosis this measurement is used in combination
is, therefore, a negligible factor in breadth mea with the palatal plane;
surements (Ishiguro et al, 1976). • mandibular width - measured from Ag to Ag (at
The use of ratios in a posteroanterior cephalo trihedral eminence above notch);
metric investigation is advantageous. This is because • maxillary width - two frontal lines, left and
the results can be used for comparison with other right, are constructed from the medial margins
persons or groups whose radiographs have been of the zygomaticofrontal sutures to Ag points,
taken with uncontrolled or unknown enlargement and the maxillarv width is evaluated on left and
of the different structures of the skull on the X-ray right sides separately by relating J point or point
film (Athanasiou et al, 1992). However, diagnos jugale (defined as the crossing of the outline of
tic interpretation of ratios for clinical applications the tuberosity with that of the jugal process) to
in individual cases is difficult and often unclear. these lines. In this way the maxillary width is
evaluated in relation to the mandible;
• symmetry - a midsagittal plane is constructed by
dropping a line through the top of the nasal
septum or crista galli, perpendicular to the line
Table 6 . 1 . Clinical norms for the Rickett's posteroanterior 6.1 I Variables used in the posteroanterior analysis of Ricketts et
cephalometric analysis (Ricketts et al, 1972). al (1972).
150
connecting the centres of the zygomatic arches. S v a n h o l t a n d S o l o w analysis

Asymmetry is evaluated by relating point ANS This method aims to analyse one aspect of trans
and pogonion to this midsagittal plane; verse craniofacial development, namely the rela
• intermolar width - measured from the buccal tionships between the midlines of the jaws and the
surface of the first permanent molars transversely; dental arches (Svanholt and Solow, 1977). This
• intercuspid width - the width between the tips of analysis incorporates variables that have been
the lower cuspids; designed to be zero in the symmetrical subject (6,12,
• denture symmetry - the midpoints of the upper 6.13).
and lower central incisor roots are related to the • transverse maxillary position - mx-om/ORP;
midsagittal plane; • transverse mandibular position - m-om/ORP;
• upper to lower molar relation - the differences • transverse jaw relationship - CPL/MXP;
in width between the upper and lower molars. • upper incisal position - isf-mx/MXP;
The measurement is made at the most prominent • lower incisal position — iif-m/MLP;
buccal contour of each tooth. • upper incisal compensation - isf-mx/m;
6.12 Reference points and lines used in the posteroanterior

cephalometric analysis suggested by Svanholt and Solow (1977).
(After Svanholt and Solow. 1977; reprinted with permission.)
6.13 Angles used in the posteroanterior

cephalometric analysis suggested by
Svanholt and Solow (1977). ( A f t e r
Svanholt and Solow, 1977; reprinted with
permission.)
15!
Orthodontic Cepbalotnetry
• lower incisal compensation - iif-m/mx. G r u m m o n s analysis

According to the authors, dentoalveolar compen This is a comparative and quantitative posteroan-
sations will move the midpoint of the dental arch terior cephalometric analysis. It is not related to
away from the symmetry line within one jaw normative data. The analysis is presented in two
towards the compensation line CPL. If the dental forms: the comprehensive frontal asymmetry
arch midpoint reaches the compensation line, the analysis and the summary frontal asymmetry
compensation is complete. If the midpoint of the analysis. The analyses consist of different compo
dental arch does not reach the compensation line, nents, including horizontal planes, mandibular
there is incomplete dentoalveolar compensation. morphology, volumetric comparison, maxillomandi-
Displacements of the midpoints of the dental arch bular comparison of asymmetry, linear asymmetry
in a direction opposite to the direction from the jaw assessment, maxillomandibular relation, and
symmetry line to the compensation line are called frontal vertical proportions (Grummons and
dysplastic. Kappeyne van de Coppello, 1987) (6.14).
6.14 Landmarks and abbreviations in

HSR 7 Grummons analysis. (After Grummons and
Kappeyne van de Coppello, 1987; reprint
ed w i t h permission.)
-£A
Ag Antegonial Notch Nasal Cavity at

ANS Anterior Nasal Spine Widest Point
Cg Crista Galli Zygomatic Frontal
Co Condylion Suture, Medial
(most superior aspect) Aspect
Fr Foramen Rotundum Zygomatic Arch
J Jugal Process Upper Central Incisor Edge
Me Menton Lower Central Incisor Edge
MSR Mid-Sagittal Reference Line at Crista Galli
6.15 Horizontal planes applied in G r u m m o n s analysis. (After

Grummons and Kappeyne van de Coppello. 1987; reprinted with
permission.)
152
Posteroanterior (Frontal) Cephalotnetry
The practical procedure includes the following nasal spine (ANS) to the chin area (6.14, 6.15).
steps: An alternative way of constructing the MSR line,
1. Construction of horizontal planes (6.15) - four if anatomical variations in the upper and middle
horizontal planes are constructed: facial regions exist, is t o draw a line from the
• one connecting the medial aspects of the zygo- midpoint of Z-plane either through ANS or
maticofrontal sutures (Z); through the midpoint of both foramina
• one connecting the centres of the zygomatic rotundum (Fr-Fr line).
arches (ZA); 3. Mandibular morphology analysis (6.16) - left-
• one connecting the medial aspects of the jugal sided and rightsided triangles are formed
processes (J); and between the head of the condyle (Co) to the ante-
• one parallel to the Z-plane through menton. gonial notch (Ag) and menton (Me). A vertical
2. A midsagittal reference line (MSR) is construct line from ANS to Me visualizes the midsaggital
ed from crista galli (Cg) through the anterior plane in the lower face.
6.16 Mandibular morphology assessed in G r u m m o n s analysis. 6.17 Volumetric comparison applied in G r u m m o n s analysis.
(After Grummons and Kappeyne van de Coppello, 1987; reprinted (After Grummons and Kappeyne van de Coppello, 1987; reprinted
with permission.) w i t h permission.)
6.18 M a x i l l o m a n d i b u l a r c o m p a r i s o n of a s y m m e t r y used in
G r u m m o n s analysis. ( A f t e r G r u m m o n s and Kappeyne van d e
Coppello. 1987; reprinted with permission.)
153
4. Volumetric comparison (6.17) - four connected 5. Maxillomandibular comparison of asymmetry

points determine an area, and here a connection (6.18) - four lines are constructed, perpendicu
is made between the points: lar to MSR, from Ag and from J, bilaterally.
• condylion (Co); Lines connecting Cg and J, and lines from Cg to
• antegonial notch (Ag); Ag, are also drawn. Two pairs of triangles are
• menton (Mc) and formed in this way, and each pair is bisected by
• the intersection with a perpendicular from Co MSR. If symmetry is present, the constructed
to MSR. lines also form the two triangles, namely J-Cg-J
and Ag-Cg-Ag.
The two polygons (leftsided and rightsided) that are 6. Linear asymmetry assessment (6.19) - the linear
defined by these points can be superimposed with distance to MSR and the difference in the vertical
the aid of a computer program, and a percentile dimension of the perpendicular projections of
value of symmetry can be obtained. bilateral landmarks to MSR are calculated for
6.19 Linear asymmetry assessed in Grummons analysis. (After 6.20 Maxillomandibular relation assessed in Grummons analysis.
Grummons and Kappeyne van de Coppello, 1987; reprinted with (After Grummons and Kappeyne van de Coppello, 1987; reprinted
permission.) with permission.)
6.21 Frontal vertical proportions evaluated in Grummons

analysis. (After Grummons and Kappeyne van de Coppello, 1987:
154
the landmarks Co, NC, J, Ag, and Me. With the • total mandibular ratio - Bl-Me:Cg-Me;
use of a computer, left and right values and the • maxillomandibular ratio - ANS-Al:Bl:Me.
vertical discrepancies between bilateral land
marks can be listed. These ratios can be compared with common facial
7. Maxillomandibular relation (6.20) - during the aesthetic ratios and measurements.
X-ray exposure, an 0.014-inch (0.356-cm) The comprehensive frontal asymmetry analysis
Australian wire is placed across the mesio- consists of all the data described above and three
occlusal areas of the maxillary first molars, indi tracings. The summary facial asymmetry analysis in
cating the functional posterior occlusal plane. cludes only the construction of the horizontal planes,
The distances from the buccal cusps of the max the mandibular morphology analysis, and the max
illary first molar to the J-perpendiculars are illomandibular comparison of facial asymmetry.
measured. Lines connecting Ag-Ag and ANS-Me,
I and the MSR line, are also drawn to reveal dental

compensations for any skeletal asymmetry, the
so-called maxillomandibular imbalance.
8. Frontal vertical proportion analysis (6.21) -
ratios of skeletal and dental measurements, made
Grayson analysis
A method of analysing craniofacial asymmetry with
the use of multiplane posteroanterior cephalometry
has been developed by Grayson et al (1983).
Landmarks are identified in different frontal planes
along the Cg-Me line, are calculated. The fol at selected depths of the craniofacial complex and
lowing ratios are taken into consideration (Al: subsequent skeletal midlines are constructed. In this
upper central incisor edge, Bl: lower central way, the analysis enables visualization of midlines
incisor edge): and midpoints in the third (saggital) dimension. The
• upper facial ratio - Cg-ANS:Cg-Me; midpoints and midlines may be combined and a
• lower facial ratio - ANS-Me:Cg-Me; 'warped midsaggital plane' can be the outcome of
• maxillary ratio - ANS-A1:ANS-Me; this analysis.
• total maxillary ratio - ANS-Al:Cg-Me; In practice, the analysis is performed on three dif
• mandibular ratio - Bl-Me:ANS-Me; ferent acetate tracing papers using the same pos-
6.22 Separate acetate tracings are made on the same radiograph, 6.23 Tracing I. (A) Orbital rims; (B) Pyriform aperture; (C)
corresponding to structures of the lateral view in or near the Maxillary and mandibular incisors; (D) Inferior border of
three planes indicated. (After Grayson et al, 1983; reprinted with symphysis. (After Grayson etal, 1983; reprinted with permission.)
permission.)
155
teroanterior cephalogram. Structures are traced On the second acetate sheet the greater and lesser
within or near the three different planes indicated wings of the sphenoid, the most lateral cross-section
on the lateral view (6,22). of the zygomatic arch, the coronoid process, the
On the first acetate sheet, the orbital rims are maxillary and mandibular first permanent molars,
outlined, along with the pvriform aperture, the the body of the mandible, and the mental foramina
maxillary and mandibiilar incisors, and the are traced (6.24). These structures are located on or
midpoint of the symphysis (6.23). In this first near the deeper coronal plane B.
drawing, the anatomy of the most superficial aspect The third tracing, containing structures and land
of the craniofacial complex, as indicated by plane marks corresponding to plane C, includes the upper
A, is presented. surface of the petrous portion of the temporal bone,
6.24 Tracing 2. (A) Greater and lesser wings of the sphenoid; (B)
The most lateral cross-section of the zygomatic arch; (C) The
c o r o n o i d p r o c e s s ; ( D ) T h e m a x i l l a r y and m a n d i b u l a r f i r s t
permanent molars; (E) The body of the mandible; (F) The mental
foramina. (After Grayson et al, 1983; reprinted w i t h permission.)
6.25 Tracing 3. (A) Superior surface of the petrous portion of

the temporal bone; (B) Mandibular condyles with outer border of
the ramus; (C) Mastoid process. ( A f t e r Grayson e t al, 1983;
6.26 (A) Midline construct for

t h e A p l a n e ; (B) M i d l i n e con
struct for the B plane; (C)
M i d l i n e c o n s t r u c t f o r the C
plane. (After Grayson e t a l , 1983;
156
Posteroanterior (Frontal) Cephalofftetry
the mandibular condyles with the outer border of The same principles are applied in planes B and C.
the ramus down to the gonial angle, and the For plane B the midpoints that are used are point
mastoid processes with the arch of temporal and Msi, which is the bisector between points Si, point
parietal bones connecting them (6.25). Mz between the centre of the zygomatic arches,
For each tracing, midsagittal midlines are con point Mc between the tips of the coronoid process
structed as follows (6.26): es, point Mx between left and right maxillare, and
For plane A, the centrum of each orbit is identi point Mf between left and right mental foramina.
fied and the midpoint Mce is constructed, the most For plane C the midpoints used are point Md
lateral point on the perimeter of each pyriform between the heads of condyles, Mm between the
aperture is located, and the midpoint Mp is marked, innermost inferior points of the mastoid process
the midpoint Mi is constructed between the max es, and Mgo between the two gonions.
illary and mandibular incisors, and point Mg is If the three tracings are superimposed (6.27), the
identified at the Gnathion area. phenomenon of warping within the craniofacial
All these midpoints are close to the midline in skeleton can be observed. In most asymmetric
some sense. The midline in plane A can be con patients, the craniofacial asymmetry will appear less
structed by connecting all above-mentioned mid severe in the most posterior and in the deep-lying
points. The result is a segmented construction of cranial structures. This multiplane analysis gives the
these midlines, whose angles express the degree of possibility to view the sagittal plane in posteroan
asymmetry of the structures in this specific plane. terior cephalometry.
6.27 The midline constructs progressively deviate laterally as

one passes from posterior' t o anterior planes of the face. (After
Grayson et al. 1983; reprinted w i t h permission.)
157
Hewitt analysis teroanterior cephalograms have been presented

According to this method (Hewitt, 1975), analysis (Cheney, 1961; Letzer and Kronman, 1976; Mulick,
of craniofacial asymmetry is performed by dividing 1965; Shah and Joshi, 1978; Thompson, 1943).
the craniofacial complex in constructed triangles,
the so-called triangulation of the face. The different
angles, triangles and component areas can be POSTEROANTERIOR CEPHALOMETRIC
compared for both the left side and the right side NORMS IN NORMAL SUBJECTS
(6.28). The regions that can be described in this way
are: Many articles and atlases have been published on
• the cranial base; normative data related to the facial structures that
• the lateral maxillary region; have been studied by means of lateral cephalome
• the upper maxillary region; try. However, publications describing the use of pos-
• the middle maxillary region; teroanterior cephalometric radiography are
• the lower maxillary region; relatively few.
• the dental region; and In recent years, there has been a growing demand
• the mandibular region. for extended roentgenocephalometric control
material as a result of the refinements in syndrome
Chierici m e t h o d identification and the advances in the treatment of
This method focuses on the examination of the craniofacial anomalies. All existing cephalometric
asymmetry in the upper face (Chierici, 1983). A line data are of value for the diagnosis of various types
connecting the lateral extent of the zygomati- of craniofacial anomalies and for monitoring
cofrontal sutures on each side (line zmf-zmf) is con growth of persons or groups of corresponding age
structed. Line x is then drawn through the root of and race. Data that have been collected, elaborat
the crista galli perpendicular to zmf-zmf. ed, and published in previous investigations are
Examination of the different structures and land extremely useful, taking into consideration that
marks on both left and right sides on the same plane elective roentgenocephalometric studies to describe
and the deviation of midline structures can identify normal dentofacial development are no longer
craniofacial asymmetry and reveal its extent (6.3). possible from the ethical point of view.
The Bolton standards (Broadbent et al, 1975)
A literature search shows that in the past several have been derived from actual cases that presented
other methods or analyses aiming to assess the pos- a so-called normal condition of dentofacial mor-
6.28 Triangulation of the face. (After Hewitt, 1975; reprinted

with permission.)
158
Posteroanterior (Frontal) Cephalotnetry
phology as well as arch alignment. The Bolton REFERENCES

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development and growth are in the form of pos
teroanterior cephalometric templates for one sex Athanasiou AE, Droschl H, Bosch C (1992) Data
group (both males and females pooled together) for and patterns of transverse dentofacial structure of
the age period from three to 18 years. The Bolton 6- to 15-year-old children: A posteroanterior
standards present certain limitations for clinical and cephalometric study. Am J Orthod Dentofacial
scientific applications. These standards give only Orthop 101:465-71.
modal (not average) tracings, and they do not carry
with them any mensurational data. Athanasiou AE, Moyers RE, Mazaheri M,
Normal posteroanterior cephalometric standards Toutountzakis N (1991) Frontal cephalometric
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relative to orbital height were published by Craniomaxillofac Surg 19:249-53.
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The data were acquired from 102 young Danish (1975) Bolton Standards of Dentofacial
males. These investigations dealt with midline dis Development and Growth. (CV iVtosby: St Louis.)
crepancies (Svanholt and Solow, 1977), patterns of
associations (Solow, 1966), and sex differences Cheney EA (1961) Dentofacial asymmetries and
(Ingerslev and Solow, 1975). their clinical significance. Am] Orthod 47:814-29.
The normal standards for children, which have
been published by Droschl (1984), are derived from Chierici 0 (1983) Radiologic assessment of facial
a population of 666 untreated schoolchildren in asymmetry. In: Harvold EP (ed) Treatment of
Graz, Austria. This was a cross-sectional study and Hemifacial Microsomia. (Alan R Liss: New York)
included children with ages ranging from six to 15 57-87.
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of Class I and Class II division 1 malocclusions. Costaras M, Pruzansky S, Broadbent BH Jr (1982)
Utilizing the posteroanterior cephalograms of Bony interorbital distance (BIOD), head size, and
588 children from DroschPs material, Athanasiou level of cribriform plate to orbital height. I. Normal
et al (1992) studied eight linear variables, two standards for age and sex. / Craniofac Genet Dev
angular variables, and 10 ratios in an age range of Biol2:S-n.
six to 15 years.
Very valuable normative posteroanterior Droschl H (1984) Die Fernroentgemverte
cephalometric data, derived from the University of Vnbehandelter Kinder zwischen 6. und IS.
Michigan study, have been presented by Movers et Lehensjahr. (Quintessence: Berlin.)
al(1988). Normative data are presented for both
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data include linear measurements, ratios, and Philadelphia: WB Saunders: Philadelphia) 297-304.
mgular measurements.
Posteroanterior cephalorruetcu: o/ict^.-^to^ 4-&*L2» ■r^tro R5> \vy6Y) The differential diagnosis and
br Chinese have been produced by Wei (1970) fol treatment of crossbites. Dent Clin North Amer
ding examination of 84 males and 22 females. 25:53-68.
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Grayson BH, McCarthy JG, Bookstein F (1983) Moorrees CFA (1985) Natural head position. In:
Analysis of craniofacial asymmetry by multiplane Jacobson A, Caufield PW (eds) Introduction to
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Philadelphia) 84-89.
Grummons DC, Kappeyne van de Coppello MA
(1987) A frontal asymmetry analysis./ Gin Orthod Moyers RE, Bookstein FL, Hunter WS (1988)
21:448-65. Analysis of the craniofacial skeleton: Cephalo-
metrics. In: Moyers RE (ed) Handbook of
Hewitt AB (1975) A radiographic study of facial Orthodontics. (Year Book Medical Publishers:
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Ingerslev CH, Solow B (1975) Sex differences in Mulick JF (1965) An investigation of craniofacial
craniofacial morphology. Ada Odont Scand asymmetry using the serial twin study method. Am
33:85-94. J Orthod 51:112-29.
Ishiguro K, Krogman WM, Mazaheri M, Harding Nakasima A, Ichinose M (1984) Size of the cranium
RL (1976) A longitudinal study of morphological in patients and their children with cleft lip. Cleft
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patients from birthj to six years of age. Cleft Palate
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Solow B, Tillgren A (1971) Natural head position
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Orthod 40:141-7.
161
CHAPTER 7
Applications and Limitations of Cephalometry in

Diagnosis and Treatment Evaluation in Orthodontics
Louis A Norton, Sam Weinstein and Joo-Yeun him
INTRODUCTION for projective distortion (Broadbent et al, 1975).
Therefore, an Orientator was introduced. The
The literature associated with the use of roentgeno- Orientator was an acetate overlay placed over the
graphic cephalometry suggests a limitless potential two films superimposed along the Frankfort hori
lor this technique. Its genesis was in the physical zontal plane. Although the Orientator reconstruct
anthropologist's concern with quantifying shape and ed landmarks determined from the lateral and
size of the head as well as the skull. posteroanterior headfilms back into three-dimen
Physical anthropometric measuring techniques, sional points in space, its use was not widely
as applied to the living head, Jed to the development accepted by the orthodontic community.
of the roentgenographic cephalometer (Broadbent,
Most of the cases encountered by c/micians were
1931; Hon-ath, 1931;, itspvtemia) was document-
cd in a classic review paper (Krogman and Sassouni, symmeCticmdtkt conventiona/fatera/cepnafogram
alone with normative M^nH^r^c r>rmn/^^ *>A~~^^~
B57), wnere trie diagnostic methods ror obtaining information for diagnosis and treatment planning.
$ke\eta\-devAta\ te\at\or\s vjetc desct\Y>ed. S'\v\cc xYven, T\\ere were some VnVietent proYAems and V\m'vtatu>ns
cephalometrics has been recognized by other disci associated with the Orientator (Baumrind et al,
plines for its usefulness in both the diagnostic and 1983a, 1983b). These included variations in identi
treatment areas. Many new applications of fication of identical landmarks from two different
cephalometry have continued to emerge. Still, it cephalograms and problems of compensation for
must be remembered that cephalometry is a tool. enlargement differences between two films.
It cannot exceed its inherent limitations. Its Conventional roentgenographic studies have not
maximum usefulness is largely dependent on the been useful for the accurate assessment of craniofa
sensitivity of the user's interpretation and the relia cial anomalies and facial asymmetries. The three-
bility of his or her judgement. dimensional nature of the skull is obvious, bur
cephalometric schemes rely on two-dimensional
orthogonal roentgenographs. The two-dimensional
BACKGROUND FOR APPLICA nature of the cephalogram requires that the
TIONS AND LIMITATIONS OF anatomic landmarks of the left and right halves be
CEPHALOMETRICS mirror images of each other at the midsagittal plane.
This cannot be achieved in patients with facial
With the introduction of the cephalostat asymmetry.
(Broadbent, 1931), roentgenographic cephalometry, Over the years, quantitative data on facial pro
in conjuction with clinical analyses, has affected portions and profile indices have been obtained
orthodontic diagnosis and treatment planning. In from lateral and frontal cephalometric radiographs.
addition, it has been used in quantitative analysis of Although conventional cephalograms have affected
facial growth and development and in orthognath- diagnosis and treatment planning of a wide variety
ic surgery treatment planning. Because roentgeno of cases, the limitations of these cephalograms as
graphic cephalometry is a two-dimensional valid clinical tools cannot be ignored (Baumrind and
representation of a three-dimensional craniofacial Frantz, 1971a, 1971b). In fact, subsequent studies
complex, it has been recommended that skeletal have shown errors associated with projective dis
landmarks in the lateral headfilm should be co-ordi tortion, size distortion, errors in position, and
nated with the posteroanterior headfilm to correct landmark identification and interpretation (Wein-
163
stein and Solonche, 1976). Other investigators went Medical photogrammetry

further and questioned the validity of cephalomet Medical photogrammetry (the taking of measure
ric conventions. They felt that these conventions had ments from standard photographs of the face) has
no clear basis in either biology or biometrics as they been widely used to obtain quantitative data on
suffered both from conceptual handicaps and from facial proportions and profile indices. This technique
technical handicaps (Moyers and Bookstein, i?79). was used to obtain aesthetic standards from studies
Since the invention of the ccphalostat, many of paintings, sculptures, and photographs of beauty-
researchers have tried to correct projective distor queens. Using standardized photographs for quan
tions and to improve the reliability of measurer.--nts titative analysis of the face, the two greatest sources
(Adams, 1940; Brodie, 1941; Salzmann, ! >64; of error in photogrammetry were found to be the
( Wylie and Elsasser, 1948). Attempts were made to

standardize these projective distortions at various
replication of pose position (Tanner and Weiner,
1949) and distortions due to the two-dimensional
target-film distances for every cephalometric point. nature of photographs (rarkas and Kolar, 1987).
A compensator was made, which could correct for The physical anthropological methods developed
projective distortion on the posteroanterior film. many centuries ago have become a valuable clinical
The errors found were within the allowed limits of tool for measuring the face. The multi-dimension
scientific accuracy. The validity of many cephalo al measurements quantify the relationship of the
metric analyses has not been documented. underlying bony skeletal architecture to the soft
Subsequent studies have shown that errors asso tissue drape. This aids in our understanding of the
ciated with superimposition, landmark identifica underlying structural facial problems that influence
tion, and tracing may be significant enough to affect facial soft tissue aesthetics.
diagnosis and treatment decisions (Hixon, 1956; Coplanar stereometry has been used as a
I Gron, 1960). standard procedure for making terrestrial maps
from aerial photographs since the early 1900s. The
same principle has been used for making quantita
I PHOTOCEPHALOMETRY tive measurements of the face using coplanar
roentgenographic cephalometrics. The first clinical
In recent years, studies have pursued new resources use of the stereophotogrammetry was reported in
and techniques to replace or supplement the stan 1944 by Thalmaan-Degen. He studied facial growth
dard cephalogram. One simple approach was pho- changes as sequelae to growth and orthodontic
tocephalometry (Hohl et al, 1978). This was an treatment. Other researchers studied growth
attempt to obtain more accurate and detailed infor changes, anthropometry, and different treatment
mation about soft tissues in both the head views by modalities using stereophotogrammetry (Bjorn et al,
superimposition of co-ordinated headfilms with 1954; Hertzberg et al, 1957; Berkowitz and Cuzzi,
photographs. The basic assumption was that the 1977).
photographic images placed on the skin of the Stereophotogrammetry allowed for measurement
patient could be accurately superimposed on cor of three-dimensional objects without the posing
responding markers in a cephalogram. error found in photogrammetry. A three-dimen
This technique would provide quantifiable data sional X-ray stereometry was produced from paired
about soft tissues not observable on the standard coplanar images, in order to allow for accurate
cephalometric film. In another study, researchers merging of three-dimensional co-ordinate data from
attempted to quantify errors of magnification and head films, study casts, and facial photographs
distortion, and the location of errors on lateral and (Baumrind et al, 1983a, 1983b).
frontal photographic landmarks involved in photo-
cephalometry (Phillips et al, 1984). Other methods
The results of these studies showed that the dif Other methods, such as morphanalysis, mesh grid
ferences in the enlargement factors between the pho analysis, implant studies, finite element method and
tographic and radiographic images were significant. computerized tomography, have been used as alter
This called into question the validity of quantitative natives for obtaining measurements of the face.
comparisons of superimposition of the two images. Techniques for multi-dimensional X-ray imaging,
164
Applications and Limitations of Cephalometry
such as tomography and stereoscopic X-rays, have In a reuse of the original ideal of Broadbent and
been invented for constructing a two-dimensional Bolton, a computer-aided three-dimensional
individual within a three-dimensional space (Baum- cephalcmetrics approach based on two-dimension
iind and Moffit, 1972). In model making, three- al cephrJograms has been recently described
dimensional models have been created directly from (Cutting et al, 1986). This method was ideal for
CTscan data (7.1). Computer-aided design (CAD) landmarks that are easily identifiable in the cephalo-
software has been used to plan complex surgical grams; however, it was unsuitable for landmarks
treatment (Cutting et al, 1986). Although these that did lot lie on the skeleton. Three-dimensional
newer methods provide three-dimensional repre information was produced from lateral and pos-
sentation of the craniofacial complex, the draw teroanterior cephalograms using existing cephalo-
backs of these approaches are numerous. In stat-based data. By integration of the posteroanterior,
basilar, and lateral cephalograms, it has become
particular, their complexity and cost have made
possible to locate the three-dimensional relation
them impracticable for ordinary use, and they are at
ships of anatomic points to each other (Grayson et
present restricted to multispecialty craniofacial
al, 1988) (7.2).
anomalies teams.
7.1 A C T scan craniogram

allow* the clinician t o visualize
craniofacial anomalies in a
multidimensional mode.
165
7.2 ( A ) Three-dimensional Bolton standards for the 16-year-old

male patient, t o be compared t o the patient with hemifacial
microsomia; (B) View of the patient and wire-frame drawing of his
starting f o r m ; (C) Mock surgery on three-dimensional cephalogram
combining computer optimization to match the Bolton 16-year
male patient with modifications introduced by the clinician. The
image can be viewed and evaluated from any direction. (After
Grayson et al, 1988; reprinted w i t h permission.)
166
Recently, a new software product called sonically by the microphone array. Using this
IDigiGraph has enabled clinicians to perform non- method, cephalometric analyses and monitoring of
invasive and non-radiographic cephalometric a patient's treatment progress can be performed as
analysis (7.3). This device uses sonic digitizing elec often as desired without radiation exposure. In
tronics to record cephalometric landmarks by lightly addition, data collection is non-invasive and, with
touching the sonic digitizing probe to the patient practice, relatively efficient. This method is partic
and pressing the probe button. The probe emits a ularly useful in quantifying facial asymmetries (7.4).
sound and the corresponding landmark is recorded
7.3 Patient undergoing digitagraphic data input.
7.4 Patient showing facial asymmerty on a CRT which can be

analysed by a computer software system.
167
ANALYSIS ASSESSMENT USING CEPHALOMETRIC

ANALYSIS
All radiographs of the head taken for orthodontic
purposes should be considered as diagnostic skull Patient head orientation becomes a problem when
films before they are thought of as cephalograms. facial relationships are evaluated. Both the Frankfort
With this attitude, the clinical orthodontist will be horizontal and the sella nasion planes vary from
more likely to review the films carefully and to inter person to person in their relationships with the true
pret them for significant deviations from the normal horizontal plane (a line perpendicular to a plumb
and evidence of pathology. Only after completion of line). Obviously, an individual person may have a
thoughtful, systematic evaluation should cephalo- high or low ear position, orbit, or sella tursica. An
metric tracings or other morphometric analyses be attempt to account for these natural anatomical
done. variations can be made by taking cephalometric X-
Cephalometric analysis is used to assess, ray films in what is called natural head position.
compare, express, and predict the spatial relation This has been defined as the position the head
ships of the soft tissues and the craniofacial and assumes when a person is standing and his visual
dentofacial complexes at one point or over time axis is horizontal. A horizontal line is drawn at a 90°
(7.5). This analysis can be either objective or sub angle from a plumb line registration superimposed
jective. The accuracy of the information depends on the film (Moorrees and Kean, 1958). This
upon adherence to the basic principles in producing horizontal line is used to check the variation of the
head films and the care used in their evaluation. usual cranial base reference planes. For example, a
Objective evaluation involves the quantification true horizontal can be used to provide a check for
of spatial relationships by angular or linear mea possible deviation in the orientation of the sella-
surements. Subjective evaluation involves the visu nasion plane (S-N) by comparing the angle between
alization of changes in spatial relationships of areas S-N and true horizontal. If S-N has a bizarre angu-
or anatomical landmarks within the same face and lation, a correction can be made on all measure
relating them to a common point or plane over time. ments that use S-N as a reference (Khouw et al,
Cephalometrics has been used in research to study 1970). Although variations occur in the reproduc
the growth and development of the face and its com- tion of the natural head position, intracranial ref-
ponenrparrs. If is used cJinicaJJv fo assess the effect erence hnes are subject to greater biological
of orthodontic therapy on the spatial relationship of variations than those met in the registration of
the teeth to jaws or on individual teeth or groups of natural head position.
teeth. It is an effective tool in evaluation of dental In selecting registration areas for evaluating
rehabilitation procedures, of surgical (skeletal repo cephalometric changes, it is important to select only
sitioning) procedures, or a combination of the two.
those areas that are stable or least changing. The
7.5 Schematic approach t o patient facial analysis.
168
ssella-nasion plane and Bolton plane, registered on would be maximum registration on the internal
the anteroposterior position of the sella fossa, are architecture of the mandibular symphysis, the
frequently employed to study the overall changes mandibular canals, and the third molar tooth crypts.
within the face produced by growth or treatment.
Unfortunately these planes are determined by points COMPARISON USING CEPHALOMETRIC
on the exoskeleton that are subject to a variety of ANALYSIS
growth influences. The most satisfactory method of
overall cranial registration is to superimpose: Cephalometrics may be used to compare morpho
• the planum sphenoid; logical variations of the craniofacial and dentofacial
• the ethmoid plane; patterns of different racial, age, sex, and dental
• the inner shadow of the contour of the middle occlusion groups. It has also been used to compare
cranial fossa; and the effect of two or more different mechanothera-
• the floor of the anterior cranial base formed by peutic approaches on the spatial relationship of the
the orbital vaults. jaws and teeth, and to compare their effect on indi
vidual teeth or groups of teeth.
These structures maintain a relatively fixed rela Using a cephalometric technique to make com
tionship to one another and can therefore be used parisons involves developing a statistically repre
to demonstrate the overall changes within the face. sentative sample for each of the groups to be
This technique of superimposition registration compared. Most studies have been cross-sectional
applies to the serial study of an individual only. For in nature and not subjected to rigorous statistical
group or population studies, the sella-nasion plane, analysis. Again, points and planes from which the
Bolton plane, or other standard planes based on average measurements are made are derived for each
anatomical points can be used. group. These points and planes must be readily dis
When studying changes within the maxilla, the cernible anatomic entities and they must be common
least changing structures from which to view tooth to all records and capable of being accurately
movement and maxillary growth are: located. In comparison studies, anatomical planes
• the anterior and posterior portion of the floor of should be used for reference rather than maximum
the nasal cavity and roof of the oral vault; registration of areas with relatively stable relation
• the anterior nasal spine areas; and ships because different people of varying size and
• the internal architecture of the anterior part of anatomic relationships are involved. Any differences
the maxillary bone. observed are relative to the common point or plane
from which such differences are noted. Observations
Registrations on these structures are used primarily and conclusions that have been drawn have not
to study changes in the relative position of teeth usually stressed this fact.
within the bone itself.
Metallic implants were used in the mandibles of
growing children to demonstrate that cephalomet- EXPRESSION OF RELATIONSHIPS USING
jric registration on anatomical landmarks that CEPHALOMETRICS
change with growth could result in erroneous con
clusions (Bjork, 1955). For example, the accepted Cephalometrics is used to express relationships
method was the superimposition of the cross-section within the craniofacial and dentofacial complexes.
of the mandibular symphysis and the registration of In addition, it has enabled clinicians to locate the
the posteroinferior borders of the mandible. Bjork's probable causative area(s) of the dysplasia. The
studies showed the posteroinferior border was language of cephalometrics is based on measure
subject to apposition of bone in some instances and ments that quantify spatial relationships of parts
resorption in others. He noted, however, that the of the face and dentures and their relationship to
internal architecture of the mandibular symphysis, each other.
the mandibular canals, and the third molar tooth In 194H, the first complete analysis was published
crypts maintained a relatively constant relationship which quantified variations in facial relationships
jtoeach other as well as the metallic implants. (Downs, 1948). The author described variations he
Therefore, the most acceptable method of analy found in 20 individuals with excellent occlusions
sing mandibular growth or tooth movement or both using 10 angular measurements; five of these were
169
measurements of skeletal relationships and five were terms, the spatial relationships within the dentofa-
measurements of dental relationships. The analysis cial and craniofacial complexes. Each analysis
compared the clinically significant relationship of enables the clinician to understand and to commu
the maxilla and mandible to each other as well as to nicate the limitations and possibilities inherent in an
the cranium. This analysis became the basis for the individual patient which may influence and lead to
new cephalometric language. The Frankfort hori success in the treatment of the dentofacial dishar
zontal plane was used as a reference plane because mony. If an analysis expresses all the relationships
of its clinical visibility and its familiarity to clini that are meaningful to the clinician, then it may be
cians. The analysis was not presented as a basis for used together with any other analysis that might
a treatment goal or standard. It was a method for employ slightly different measurements. Most
examining and quantifying the relationships of the analyses do not include all the desired inter-rela
component parts of the face and its dentures. The tionships and so must be combined with parts from
goal was to assess the severity of the facial and others for completeness.
dental malocclusion and to locate the probable A basic analysis should include a way of assess
etiology. Another contemporary analysis assessed ing the following spatial relationships:
antero-posterior and vertical craniofacial dysplasias. 1. Mandible to the cranium.
This approach used linear measurements instead of 2. Maxilla to the cranium.
the angular measurements of Downs (Wylie, 1947). 3. Mandible to the maxilla.
A widely used analysis was.based upon the 4. Mandibular denture to the maxillary denture.
angular measurements among three planes, namely 5. The prominence of the chin point relative to the
the Frankfort horizontal, mandibular plane and the mandibular denture base.
axial inclination of the lower incisor to these respec 6. Axial and positional relationships of the maxil
tive planes (Tweed, 1954). This analysis was his lary and mandibular incisors to their respective
torically important because Tweed used these supporting bones and skeletal planes.
measurements to establish a treatment plan and 7. Facial proportions - vertical relationships of parts
treatment objectives that included consideration of to the whole.
dental extractions and profile goals.
Several years later it was observed that the Each of these relationships can be expressed in dif
maxilla and mandible could be related to the ferent ways so that a composite analysis can be
cranium anteroposteriorly by the angles SNA and compiled so as to be most meaningful to an indi
SNB (Riedel, 1959). The difference between the vidual clinician. In essence, the clinician is shopping
values was an expression of the severity of the at an anatomical relationship supermarket. He
denture base problem. This was the first use of the selects a balanced meal (analysis) from various types
sella-nasion plane for individual patient analysis. of foods (spatial relationships) in each aisle
These reference planes and angles are now standard (anatomical structure). The more nutritious the meal
for most analyses. A combination of all these mea- (inclusive the analysis) the healthier (better
surements created a more broadly based analysis, informed) he will be.
treatment-plan aid, and objective guide (Steiner, No single measurement is adequate for an
1953). This assessment took the maxilla, mandible, analysis, but the sum of the collective relationship
cranial base, denture and profile into account. measurements will provide the clinician with a much
Again, Steiner attempted to use the quantification clearer idea of his patient's skeletal and dental
of certain dental and skeletal relationships to help problems. Furthermore, it should be obvious that
in making the decision whether to extract teeth or a cephalometric analysis by itself is inadequate for
not. Numerous other analyses have been introduced arriving at a diagnosis for the orthodontic patient.
for the assessment of orthodontic patients as a way It is only one important cog in our diagnostic gear.
of understanding the implications of treatment Only after an assessment of all records (dental casts,
regimens. photographs, radiographs, and the patient's medical
One is frequently asked, which one of the many and dental history) should a final diagnosis and
analyses is the best one for quantifying, in objective treatment plan be determined.
170
PREDICTION USING CEPHALOMETRICS that dental and skeletal patterns closely influence
the soft tissue profile.
I The cephalometric technique may be used to predict Another study quantitatively evaluated two age
desired spatial relationships of the dentofacial samples selected by artists as aesthetically pleasing
complex for surgical or orthodontic treatment or a (Burstone, 1959). The author described patterns
combination of the two. It may also be used to identified with a horizontal spatial relationship of
review progress (reanalysis) toward the attainment specific soft tissue landmarks to the underlying
of these goals throughout the treatment period. facial skeletal. It is striking that soft tissue extensions
When cephalometrics is employed for this and thickness can either augment or cancel dis
purpose, the treatment goal is determined individu crepancies in hard tissue relations.
I ally for each patient. Consideration should be given

to all influencing factors, such as age, sex, race,
growth prognosis, facial type, and malocclusion
Other age changes in soft tissue profile have been
reported in extensive and diverse studies (Burstone,
1958, 1959; Subtelny, 1961; Bowker and Meredith,
type, as well as to the spatial relationships of the 1959; Pike, 1975).
component parts of the face. No rules of thumb or The impact of differential growth of the nose on
simple formulae can be universally applied to make the facial profile is shown in many studies. Growth
this determination. is non-linear and it accelerates during the late ado
A. cephalometric evaluation makes it possible to lescent years. The increasing protrusiveness of the
determine areas of dysplasia and thus helps to pre- nose is usually masked by the vertical growth of the
| determine the effects of various surgical alternatives total face. In a prognostic sense, the clinician's
on the dentofacial pattern before surgery. manipulation of lip contours by treatment should
A word must be said about prediction of the be sensitive to the influence of the mature nose on
effects of growth. Desirable as prediction is, no the aesthetic facial profile.
method has yet been devised to make precise pre Cephalometrics is particularly useful for evalu
diction of growth a reality. Faces tend to have a ating where one is during treatment. This is what
genetically controlled individual growth direction many clinicians term reanalysis. In sailing, one has
and this direction is relatively constant throughout a destination, but shifts in wind direction, wind
the growth period. velocity, tides, and currents can make achieving the
Unfortunately, the many patients seeking ortho goal a challenge. This analogy is applicable to ortho
dontic treatment are largely people whose facial dontics. Therefore, progress cephalograms and
growth patterns vary from the usual and whose tracings allow for midcourse corrections if needed.
faces grow in an unfavorable way, varying from the The trick is to use superimposition correctly. In a
norm. Thus, prediction is probably least accurate non-growing adult patient, a progress cephalogram
where it is most needed - in the most difficult cases. generally fits the original. The changes are mostly
Diagnostic procedures in orthodontics and dental with minor dentofacial bone changes related
maxillofacial surgery are sensitive to the aesthetic to the tooth movement. In a growing patient, one
implications of the facial soft tissue. Facial aesthetics must superimpose upon parts that change little with
has an underlying condition. Attempts to quantify growth, such as the anterior cranial base.
the relationship of parts show the subjective nature Finally, it is necessary to see what was affected in
of the problem. The eye can integrate a group of individual bones. Therefore, one superimposes upon
variables into either a pleasing or a displeasing the maxilla on a line from ANS to PNS, and the
whole. A large nose in one individual may mandible on the mandibular plane starting at the
contribute to an aesthetically displeasing face, while mandibular symphysis. An assessment of mandibu
the same-sized nose in another may fit well into an lar growth is determined by the incremental steps of
acceptably aesthetic whole. articulare as it crosses the neck of the mandibular
Soft tissue aging after the teenage years usually condyle.
, results in flattening and widening of both upper and The anteroposterior angular and vertical position
lower lip*. Two j&udirs j.wd j» cfifll&tti&p j5i*wt*flf tnftfhftfcettfc, wiferrci5mpareaJ to a treatment-objec
based on judged opinions of beauty (Peck and Peck, tive tracing, allows one to assess progress and the
1970; Riedel, 1959). Beauty contestants were eval need for corrections. Also, one can determine if
uated and their lip thickness and facial convexity reaching treatment goals is feasible or if compro
toere found to be highly variable. It was concluded mises should be considered. It is often said that in
171
planning orthognathic surgery, one wants to REFERENCES

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the problem, there appears to be no correlation 84:292-312.
between cephalometric goal envelopes and stability.
We know too little about untoward forces from soft Baumrind S, Moffit F, Curry S (1983b) The
tissues, function, and aging to give a definitive geometry of three dimensional measurements from
answer about stability. Therefore, cephalometrics paired coplanar X-ray images. Am ] Orthod
can serve as a guide but not a guarantee of stability. 84:313-22.
There are, without doubt, some clues for success in
using standards, but the issues involved are far more Berkowitz S, Cuzzi J (1977) Biostereometric analysis
complex for our present primitive two-dimensional of surgically corrected abnormal faces. Am] Orthod
analyses. 72:526-38.
Bjork A (1955) Facial growth in man, studied with

CONCLUSION the aid of metallic implants. Acta Ordont Scand
13:9-34.
Cephalometrics has given us a way of placing the
historical dental problem within the dentofacial Bjorn HC, Lunquist C, Hjelstrom P (1954) A pho-
complex. It has allowed us to quantify what was a togrammetric method of measuring the volume of
very subjective problem. Unfortunately, as data are facial swelling. / Dent Res 33:295-308.
generated, one tends to worship the abstract
numbers and lose sight of the problems they may Bowker WD, Meredith HV (1959) A metric analysis
represent. We are guilty of this offence. The future of the facial profile. Angle Orthod 29:149-60.
of cephalometrics - as it becomes more integrated
with computerized technology - appears bright. It Broadbent BH (1931) A new X-ray technique and
affords us the opportunity to use these data in three its application to orthodontics. Angle Orthod
dimensions. The promise of cephalometrics as a 1:45-66.
diagnostic and prognostic tool may yet be fulfilled.
Broadbent BH Sr, Broadbent BH Jr, Golden W
(1975) Bolton Standards of Dentofacial
Developmental Growth. (CV Mosby Co: St Louis.)
Brodie AG (1941) On the growth of the human

head from the third month to the eighth year of life.
Am } Anat 68:209-62.
Burstone CJ (1958) Integumental profile. Am]

Orthod 44:1-25.
172
Applications and Limitations of Cepbalometry
Burstone CJ (1959) Integumental contour and Krogman W, Sassouni V (1957) A Syllabus in

extension patterns. Angle Orthod 29:93-104. Roentgenographic Cepbalometry. Copyright
Library of Congress: Philadelphia 57-9556
Cutting C, Bookstein FL, Grayson B, Fellingham L, (personal publication).
McCarthy JA (1986) Three dimensional computer
aided design of craniofacial surgical procedures; Little RM, Riedel RA, Stein, A (1990) Mandibular
optimization and interaction with cephalometric and length increase during the mixed dentition:
CT-based models. Plast Reconst Surg 77:886-7. postretention evaluation of stability and relapse. Am
J Orthod Dentofacial Orthop 97:343-404.
Cutting C, Grayson B, Bookstein FL, McCarthy J A
(1986) Computer aided planning and evaluation of Moorrees CFA, Kean MR (1958) Natural head
facial and orthognathic surgery. Clin Plast Surg position, a basic consideration for the analysis of
13:449-62. cephalometric radiographs. Trans Eur Orthod Soc
34:68-81.
Downs WB (1948) Variations in facial relationships:
their significance in treatment and prognosis. Am Movers RE, Bookstein FL (1979) The inappropri-
JOrthod 34:812-40. ateness of conventional cephalometrics. Am J
Orthod 75:599-617.
Farkas LA, Kolar JC (1987) Anthropometries and
art in the aesthetics of women's faces. Clin Plast Peck S, Peck H (1970) A concept of facial esthet
Surg 14:599-616. ics. Angle Orthod 40:284-317.
Grayson B, Cutting C, Bookstein FL, Kim H, Phillips C, Greer J, Vig P, Matteson S (1984)
McCarthy JA (1988) The three dimensional Photocephalometry: errors of projection and
cephalogram theory, technique, and clinical appli landmark location. Am J Orthod 86:233-43.
cation. Am J Orthod Dentofacial Orthop
94:327-37. Riedel R (1959) An analysis of dentofacial rela
tionships. Am ] Orthod 43:103-19.
Gron PA (1960) A geometric evaluation of image
size in dental radiography./ Dent Res 39:289-301. Riedel R, Little RM, Bui TD (1992) Mandibular
extractions - postretention evaluation of stability
Hertzberg HTE, Dupertuis CW, Emmanueal I and relapse. Angle Orthod' 62:103—16.
(1957) Stereophotogrammetry as an anthropomet-
rictool. Photogramm Engineering 23:942-51. Salzmann JA (1964) Limitations of roentgeno
graphic cephalometrics. Am J Orthod 50:169-88.
Hixon EH (1956) The norm concept in cephalo-
metrics. Am} Orthod 42:898-906. Steiner S (1953) Cephalometrics for you and me.
AmJ Orthod 39:729-55.
Hofrath H (1931) Die Bedeutung der Rontgenfern
I und Abstandandsaufname fur die Diagnostic der Subtelny JD (1961) The soft tissue profile, growth,
| Kieferanomalien. Fortschr Orthodont 1:232-57. and treatment changes. Angle Orthod 31:105-22.
j Hohl T, Wolford LM, Epker BN, Fonseca RJ (1978) Tanner JM, Weiner JS (1949) The reliability of the
Craniofacial osteotomies: A photocephalometric photogrammetric method of anthropometry with
I technique for the prediction and evaluation of tissue a description of a miniature camera technique. Am
change. Angle Orthod 48:114-25. J Phys Anthropol 7:145-81.
Khouw FE, Proffit WR, White RP (1970) Thalmaan-Degen P (1944) Die Stereo-phologram-
I Cephalometric evaluation of patients with dentofa metrie, ein diagnostiches Hilfsmittel in der
cial disharmonies requiring surgical correction. Oral Kieferorthopadie. (University of Zurich: Zurich)
Surg Oral Med Oral Path 29:789-98. [doctoral dissertation).
173
Orthodontic Cepkalometry
Tweed CH (1954) Frankfort-mandibular incisor

angle (FMIA) in orthodontic diagnosis, treatment
planning and prognosis. Angle Orthod 24:121-69.
Weinstein S, Solonche D (1976) Special radiological

methods. Oral Set Rev 8:63-87.
Wylie WL (1947) Assessment of antero-posterio

dysplasias. Angle Orthod 17:97-109.
Wylie WL, Elsasser WA (1948) Undistorted vertical

projections of the head and lateral and posterior
anterior roentgenograms. Am J Roentgenol
60:414-17.
174
CHAPTER 8
Finding Pathology on Cepbalometric Radiographs

Andrew J Kuhlberg and Louis A Norton
INTRODUCTION With rising health care costs, it is important to

optimize the information obtained from each pro
Cephalometric radiographs reveal valuable infor cedure. Various studies have demonstrated the
mation that may transcend their orthodontic utility. relative value of cephalometric films in planning the
These findings may be far more important to the treatment of orthodontic cases (Atchison et al, 1991;
health of the patient than any orthodontic treat Atchison etal, 1992, Han etal, 1991). These studies
ment. To a medical radiologist, cephalometric radi support limiting radiographs to specific cases, based
ographs are considered as head films, useful for the on clinical findings. In this light, all radiographic
evaluation of head and neck pathology. Therefore, examinations must be chosen for maximum diag
as a health-care provider, the orthodontist must nostic benefit and assessed for all relevant informa
evaluate cephalograms for pathology before initiat tion. Compared to other dental specialists,
ing a cephalometric analysis. orthodontists use far more extraoral radiographs.
With increasing awareness of the risks of radia Therefore, an awareness of roentgenographic
tion exposure, the use of radiographs in orthodon- normal anatomy and its variations and the appear
Jric treatment is coming under greater scrutiny. ance of pathologic abnormalities is needed for
[ Estimations of the radiobiologic risks of dental radi complete diagnosis with cephalometric films. The
ology has been the focus of the research (Underhill normal radiographic anatomy has been covered in
etal, 1988a, 1988b; Gilda and Maillie, 1992). Chapter 2.
Estimates of the doses of radiation absorbed by The systematic review of all radiographs taken is
critical organs as well as cancer incidence and imperative for all dentists (and physicians). Efficient
fatality have been estimated from typical dental evaluation of the films is best accomplished by
radiographs. Recommendations for limiting radia methodical examination of each area of the
tion exposure have been suggested (Gilda and anatomy depicted on the film. Lateral cephalomet
Maillie, 1992). While these studies measured radi ric radiographs typically exhibit portions of the
ation doses from intraoral radiographs, the total cranium, the cervical spine, the maxilla and sinuses,
dosimetry of absorbed radiation due to cephalo- the mandible, and the dentition. Portions of the
|metric films has also been compared (Gilda and central nervous system and vasculature may present
Maillie, 1992). The data indicate that the doses with an anomalous appearance in certain diseases.
from the commonest cephalometric films are lower Each area must be checked for abnormalities before
jhan those of standard dental procedures. However, beginning the tracing and analysis of specific
[ephalometric films are more commonly taken on concern to the orthodontist. Common variations of
{rowing children, whereas radiation dose risks were normal anatomy have been reported previously
(measured with respect to adult tissues (Underhill et (Kantorand Norton, 1987). Most pathology, par
L 1988b; Gilda and Maillie, 1992). ticularly that visible by X-ray examination, occurs
In addition to the desire to minimize unnecessary in the adult population. Therefore, with the trend
K-ray exposure, the usefulness of various diagnos- toward increasing adult treatment, the likelihood of
BCtests has been examined (Atchison et al, 1991). finding pathology increases.
175
A N O M A L I E S DISCERNIBLE BY hypophyseal pathology. Before further orthodon

CEPHALOMETRY tic treatment, these findings must be evaluated by
an endocrinologist to rule out any growth hormone
abnormalities, especially hyperpituitarism and
ANOMALIES OF THE CRANIUM possible neoplastic disease.
An abnormal sella turcica is also demonstrated in
Anomalous or pathological findings in the cranium 8.2. This is an unusually large sella with poorly
can be seen by examination of the calvarium, the defined anterior and posterior clinoid processes,
sutures, and sella turcica, as well as the brain and together with a short cranial base, suggesting pitu
other soft tissues. The lateral cephalogram of an itary problems.
exceptionally large 10-year-old male patient is The mastoid processes and the bony ear are often
shown in 8.1. This patient presented for treatment overlooked in an orthodontic examination of a
of an anterior crossbite, which was readily apparent cephalometric film. In 8.3, the possibility of chronic
on the radiograph. Note the shape of sella turcica: mastoiditis is presented. The sclerotic radio-opacity
it is J-shaped, with the posterior clinoid process in the superoanterior area of the mastoid air cells
extending far superior relative to the anterior clinoid is suggestive of chronic mastoiditis or otitis interna.
processes. His dental development is somewhat Comparison with a pretreatment radiograph as well
atypical, having a normal eruption pattern for a 10 as physical signs and symptoms would aid in
year old, but with the crowns of the third molars making a judgement about this area. Long-term
already beginning to calcify. These findings, together infection in the mastoid or inner ear should be dealt
with large stature and class III malocclusion (par with expeditiously to avoid potentially severe com
ticularly the large mandible), may be indicative of plications.
8.1 J-shaped sella turcica in a 10-year-old male presenting with
mandibular prognathism. Compare the heights of the anterior and
posterior clinoid processes and notice that the posterior process
extends far more superiorly, giving the sella a J shape. Abnorm
alities of sella turcica may indicate pathology of the pituitary gland.
8.2 A p o o r l y defined, enlarged sella turcica. B o t h t h e clinoid 8.3 Sclerosis o f the superior-anterior region of the mastoid air
processes of this sella turcica are short and poorly differentiated cells, suggesting chronic mastoiditis o r otitis interna.
f r o m the cranial base.
176
Finding Pathology on Cephalometric Radiographs
ABNORMALITIES OF THE CERVICAL spine in which the body of the odontoid process and
SPINE the body of the axis are separated. Subluxation of
C l or C2 may occur, resulting in a decreased
filiation of the cervical spine is important for dis- diameter of the spinal canal and spinal cord damage.
rning any deviation from normal anatomy. Detection of this anomalv is clearlv of tremendous
Variations from normal in the cervical spine may significance for the patient's health (Hickam and
[result in increased risk to the spine cord or to the Morrissy, 1990), and it would certainly be impor
cervical nerves that contribute t o the brachial tant in determining concerns regarding physical
plexus. Patients with clefts of the lip or palate or activity and lifestyle.
jborh have an increased incidence of cervical spine A close-up view from a cephalometric film of
(anomalies (Horswell, 1991). The lateral cephalo- spondylolisthesis is shown in 8.6. Spondylolisthesis
|pam of a 14-year-old female with a history of uni is a step between two cervical vertebrae. In this case,
lateral cleft lip and alveolus is shown in 8.4. Notice the abnormality is between C4 and C5. This patient
the fusion of the vertebral bodies of C2 and C3, is at great risk of having a herniated intervertebral
A small ovoid radio-opacity can be seen superior disk in the neck, which could lead to sensory or
to the arch of Cl and the odontoid process in 8.5. motor dysfunction in the upper extremities. Careful
This appears to be an os odontoidium, a develop evaluation of the cranium and cervical spine is of
mental spinal anomaly of potentially life threaten obvious importance, owing to their association with
ing significance. Os odontoidium is a disorder of the the central nervous system.
8.6 A close-up view

of a cervical spine
anomaly called a
spondylolisthesis. a
step between the C4
and C5 vertebrae.
8.4 Fusion of C2 and C3 in a patient with cleft lip and palate.

There is an increased incidence of cervical spine anomalies in
ptients with cleft lip and palate, which makes careful evaluation of
diese patients important.
IS Os odontoidium, a developmental spinal anomaly of the axis
177
ABNORMALITIES OF THE MAXILLA AND Fluid in the maxillary sinus is seen in 8.8. It
PARANASAL SINUSES appears as a radio-opaque line parallel and superior
to the nasal floor. This is a frequent finding in post
The maxilla and the sinuses contained in the maxilla operative Le Fort I orthognathic surgery patients.
may have a variety of unusual or pathologic Findings secondary to surgery or trauma are often
findings. These range from soft tissue masses arising noted in the maxilla and associated structures.
from the mucosal linings to odontogenic pathology. Another abnormality that can be seen on ortho
Supplemental views, such as posterior-anterior dontic radiographs is shown in 8.9 and 8.10. The
cephalomctric views that are routinely used to assess dome-shaped soft tissue mass in the floor of the
facial asymmetry, often improve the visualization of maxillary sinus is consistent with a mucous reten
findings in this area. tion cyst. This is subtly apparent in the lateral
A close-up view of a radio-opaque mass in the cephalogram, but it is very evident in the P-A view.
frontal sinus taken from a P-A film is shown in 8.7. Therefore, it is important to cross-check both views
This mass is suggestive of an osteoma, a benign for suspected pathology. Notice the improvement in
tumour often found in the sinuses. The differential the ability to perceive and locate the mass in the
diagnosis of sinus masses includes osteomas, frontal view.
antroliths, and myeoliths, as well as odontogenic
tumours and cysts (Goaz and White, 1987).
8.7 A close-up view of the frontal sinuses from a P-A cephalo- 8.8 Fluid in sinus after Le Fort I orthog
gram. The radio-opaque mass is suggestive of an osteoma. nathic surgery.
8.9 Soft tissue mass on floor of the maxillary sinus. This finding is 8.10 The same patient as in 8.9, in the frontal view. The opacifi-
better visualized in the frontal view shown in 8.10. cation of the right sinus can be readily seen when compared to the
contralateral side.
178
r
Finding Pathology on Cephalometric Radiographs
ABNORMALITIES OF THE MANDIBLE mandibular second premolar. The corroborative

panoramic film demonstrates a fibrosclerotic lesion
| As with the maxilla, odontogenic pathology and associated with the apex of the mandibular right
pathology of the salivary gland and pathology of the permanent first molar.
bone within or near the mandible can often be noted The close-up of the mandibular region of a lateral
on the lateral cephalogram. Systemic disease and cephalogram in 8.13 reveals a radio-opaque shadow
trauma can also present with manifestations in the overlying the premolar roots. This well-defined mass
jaws. suggests a torus mandibularus, which is a common,
A possible odontoma in the area of the develop benign bony hyperplasia. Hyperplasias such as a
ing mandibular premolar is shown in 8.11. This can torus may be of no consequence in orthodontic
be corroborated by and better visualized on a treatment, but their differentiation from more
panoramic radiograph (8.12). In this case, it shows aggressive tumours or cysts is important.
a possible odontoma in association with the left
8.11 Possible odontoma in second premolar region, also seen in 8.12 Panoramic radiograph f r o m the patient shown in 8.1 I .
the panoramic radiograph in 8.12. N o t i c e the unusual development of the (eft second premolar as
well as the sclerosis associated w i t h the apex of the mandibular
right first molar.
8.13 A radio-opaque shadow overlying the r o o t s o f the man

dibular premolars, suggestive of a torus mandibularus, a c o m m o n
benign hyperplasia found in the jaws.
179
CONCLUSION REFERENCES
All the radiographs presented here were selected Atchison KA, Luke LS, White SC (1991)
from the graduate orthodontic clinic at the Contributions of pretreatment radiographs to ortho
University of Connecticut. These films were drawn dontists' decision making. Oral Surg Oral Med Oral
from patient records over a three-year time span. Pathol 71:238-45.
Approximately 400 were started in that time and
these findings demonstrate a prevalence of about Atchison KA, Luke LS, White SC (1992) An algo
4 % . This approximates the number of patients rithm for ordering pretreatment orthodontic radi
active in a single person private practice, pointing ographs. Am J Orthod Dentofacial Orthop
to the importance of screening all radiographs for 102:29-44.
significant pathology.
Proper evaluation of all radiographs is mandato Gilda JE, Maillie HD (1992) Dosimetry of absorbed
ry for all dentists. Because orthodontists use films radiation in radiographic cephalometry. Oral Surg
that depict areas beyond the dentition, they have an Oral Med Oral Pathol 7 3 : 6 3 8 ^ 3 .
opportunity and an obligation to make diagnoses
beyond the dentition as well. In addition to the Goaz PW, White SC (1987) Oral radiology princi
extremely important medical benefit for the patient, ples and interpretation. (CV Mosby: St Louis.)
careful evaluation of the films limits surprises during
treatment. Recognition of potential problems Han UK, Vig KW, Weintraum JA, Vig PS, Kowalski
improves the prognosis and outcome of the treat C (1991) Consistency of orthodontic treatment deci
ment. Through an organized, systematic evaluation sions relative to diagnostic records. Am J Orthod
of the cephalometric and supplemental films, one Dentofacial Orthop 100:212-19.
can make note of abnormalities in the cranium, the
cervical spine, the maxilla and sinuses, and the Hickam HE, Morrissy RT (1990) Os odontoidium
mandible. detected on a lateral cephalogram of a 9-year-old
Several remarkable or pathologic findings orthodontic patient. Am J Orthod Dentofacial
revealed by cephalometric films have been present Orthop 98:89-93.
ed. The intention has been to increase awareness of
possible pathology prior to initiating orthodontic Horswell BB (1991) The incidence and relationship
care. An oral radiography or pathology text would of cervical spine anomalies in patients with cleft lip
provide greater details of the differential diagnosis and/or palate. J Oral Maxillofac Surg 49:693-7.
of notable lesions.
Kantor ML, Norton LA (1987) Normal radi
ographic anatomy and common anomalies seen in
cephalometric films. Am f Orthod Dentofacial
Orthop 91:414-26.
Underhill TE, Chilvarquer I, Kimura K, et al (19881

Radiobiologic risk estimation from dental radiolo
gy. Part I. Absorbed doses to critical organs. Oral
Surg Oral Med Oral Pathol 66:111-20.
Underhill TE, Chilvarquer I, Kimura K, et al (1988)

Radiobiologic risk estimation from dental radiolo
gy. Part II. Cancer incidence and fatality. Oral Surg
Oral Med Oral Pathol 66:261-7.
180
CHAPTER 9
Clinical Research Applications of Cephalometry

Birte Melsen and Sheldon Baumrind
INTRODUCTION • untreated and treated subjects;

• homogeneous and mixed populations; and
Cephalomctrics - literally, the measurement of the • status at single time points and patterns of change
head - has been widely used as a tool for studying through time.
craniofacial development since long before the emer
gence of orthodontics. Before 1900, cephalometrics
was practised as a branch of anthropometry INVESTIGATIONS AMONG UNTREATED
iCamper, 1791; Broca, 1868), but it achieved high SUBJECTS
levels of measurement precision only in studies of
dried specimens. Patterns of association among skeletal and
The advent of X-ray technology (McDowell, dental variables measured on t h e same image
1900) meant that, for the first time, relatively When associations among groups of variables
accurate non-destructive longitudinal studies of the measured on the same image are studied in an
developing head became possible. Standardized attempt to identify causal relationships, the true bio
methods of teleradiology were developed indepen logical effects can be overestimated because of spuri
dently both in Europe and in the USA (Hofrath, ous topographical correlations whenever two or
1931; Broadbent, 1931), and aspects of these stan more variables being examined share common land
dardized methods were propagated into general marks and structures (Solow, 1966).
clinical use during the 1940s and 1950s (Brodie, Solow identified three types of topographical cor
1941; Downs, 1948; Ricketts, 1950; Krogman and relations:
Sassouni, 1952; Wylie, 1952; Steiner, 1953; 1. Correlations between linear variables that share
Schwartz, 1961). By the 1960s, they had become a common landmark.
routine components of treatment planning and case 2. Correlations between angular variables that share
evaluation among orthodontic specialists. a common arm.
The word cephalometrics is now used synony 3. Correlations between angular and linear variables
mously with the earlier term roentgenographic that share either a common landmark or a
cephalometrics, and direct physical measurement of common arm.
the head is restricted mainly to anthropology. In this
chapter, the word cephalometrics is used to mean Similar considerations apply when more than one
the measurement of the head on X-ray images. variable is referenced to or superimposed on a single
structure or bone.
The signs of such spurious correlations can be
RESEARCH SCOPE OF determined from topographical knowledge of the
CEPHALOMETRICS landmark configurations, and their approximate
magnitudes can be estimated from the mean and
Cephalometrics has without doubt been the most variation of the distance between line segments end-
frequently applied quantitative technique within points. Correlations that could not be predicted in
orthodontic research. It has been used to compare, this way were defined by Solow as non-topograph
differentiate, and describe: ical and were considered to have true biological
• individual subjects and groups of subjects; meaning. Solow argued convincingly that a clear dis
• normal and anomalous subjects; tinction must be drawn between topographical and
181
Orthodontic Qepbalometry
non-topographical effects before correlational Solow (1966) concluded that the biologically deter
research using cephalograms can be considered mined associations are reflections of a co-ordinat
meaningful. An example of a topographical corre ing mechanism that governs the growth and
lation is provided in 9.1. development of the dentition. This mechanism for
Solow (1966) also applied factor analysis in an the control and modification of craniofacial growth
attempt to classify the associations of craniofacial had been discussed earlier by Bjork (1954), who
morphology. He found that four major factors could noted after a survey of cephalometric X-ray analyses
account for an important part of the non-topo that compensation was dominant during adoles
graphical association: cence (9.2), while dysplastic changes appeared
1. Factors that consist mainly of linear measure mainly at an early stage of development.
ments and that reflect the general association
between the size of the head and body of the Classification of skeletal and dental
person. relationships
2. Factors that represent positive associations Many classifications of morphology have been
between cephalometric measurements of trans based on cephalometric analyses of untreated indi
verse widths and vertical dimensions and that viduals by means of single time point images. Two
express the dependence of groups of measure preconditions must, however, be satisfied:
ments spanning the same underlying region. • the presence of well-defined parameters accord
3. Factors that reflect dcntoalveolar compensatory ing to which the types are defined; and
adaptation to the intermaxillary relation, namely • the availability of normative standards to which
the tendency to maintain normal occlusal rela the values of the individuals can be compared.
tionship between dental arches despite discrep
ancy in the intermaxillary relation. A large range of variables has been used to classify
4. Factors that reflect insufficient compensation and the craniofacial skeleton for various purposes. Mar-
that could be interpreted as interaction between golis (1953) sought to classify only the facial skele
function and morphology. ton, whether developed or not, independently of
9.1 Correlation between two angular variables with a common

arm and arms without a common reference point When there is
Correlation between two angular variables
no common reference point for the arms the covartance for two
with a common arm angles with a common arm is thus equal to k times the square of
the variation coefficient for the reference point distance of the
-arms without a common reference point common arm. The sign is negative when the angles are on either
side of the common arm, and positive when they both lie on the
same side, (From SolowJ966; published with permission.)
$AB = - Ve2kt r
AB=-Ve 2 K
$ASB
$AC=Vd2k, rAC= Vd 2 k
SASC
182
race, sex, and age, whereas other authors used a more CEPHALOMETRIC ANALYSIS OF THE
■ differentiated classification based on the degree of PATIENT BEFORE TREATMENT
prognathism and retrognathism (Downs, 1948; Maj
etal, 1958; Schwartz, 1961; Gianni, 1986). Since the beginning of the 1950s, cephalometric
Vertical characteristics, especially the inclination analysis has been considered a cornerstone of ortho
of the mandible, have also been used as the basis dontic diagnosis and treatment planning. Depending
of typological classifications (Bjork, 1947; Downs, on the type of cephalometric analysis applied, the
1948; Downs, 1952; Steiner, 1953; Tweed, 1962; uses of the results have ranged from methods of
Issacson et al, 1971; Ricketts, 1976; Slavicek, 1984; localizing deviations in the facial skeleton to pro
Gianni, 1986). viding clear indications of the treatment objectives.
The impressive armamentarium of cephalometric
Identification o f s i m i l a r i t i e s a n d d i f f e r e n c e s in analyses can roughly be classified into five categories:
dentoskeletal r e l a t i o n s h i p s l . T h e Tweed (1969) and the Steiner (1953)
Similarities and differences between members of dif analyses are good examples of the type of analysis
ferent ethnic samples or between other groups (from that can be used both to establish the deviation
single or multiple time point images) have been iden from the given normal values and to provide
tified on cephalograms. Even within the field of treatment goals.
physical anthropology, cephalometrics has largely 2. In addition to the functions described before, the
replaced classical anthropometric measurement cephalometric analyses of this category also aim
methods, and studies of different ethnic groups and to contain information about growth prediction
of age-related changes have provided a valuable in relation to the definition of the treatment goals.
basis for better understanding of craniofacial Within this category, Ricketts's VTO (Visual
skeletal morphology (Brown, 1967). Anthropolo Treatment Objective) has probably drawn the
gical data have also been used in the study of the biggest attention (Ricketts et al, 1979).
relationships between the influences of genetic and 3. This category contains a large number of analyses
environmental factors (Konigsberg, 1990). that focus on the identification of discrepancies
9.2 Tracings from two different skeletal

patterns, which due t o compensatory
modelling of the alveolar process both
demonstrate perfect incisor relationship.
(From Bjork, 1954; published w i t h per
mission.)
183
by comparison with various norms, without Examples of such norms include the results of the
necessarily pointing to any specific treatment works of Riolo et al (1974), Broadbent et al
goal. Downs (1948, 1952) and Bjork (1947) (1975), and Saksena et al (1987). The same prin
analyses are examples of such analyses. ciple was used in the establishment of the Bjork's
4. A special class of analyses that represent changes norms (Bjork, 1975).
in face form through time as distortions of a Apart from establishing reference standards with
superimposed grid where either the baseline state respect to which individual patient data can be
of the patient or the values of some group norm compared, great value has been assigned to the spec
are represented as a rectilinear standard. These ification of landmarks and variables. Errors in the
methods, which probably have their origin in the location of landmarks play a significant role when
work of D'Arcy Thompson (1917), were intro evaluating the meaning of cephalometric analyses.
duced to craniofacial biology by De Coster Although the effects of random error can to a
(1939), and have been further developed by certain degree be minimized in group studies by
Moorrees and Lebret (1962). The orthogonal increasing sample size, this is no comfort when the
grids of Bookstein et al (1985) also fall into this
task is to evaluate the individual patient. Valid
general category.
judgements of difference can only be made if the
5. This category of cephalometric analysis is based deviations from normative values or the changes
on relationships between linear dimensions. related to growth or treatment exceed the method
Enlow's analysis (Enlow et al, 1971) is charac error (Grovely and Bensons, 1973; Baumrind and
terized by the absence of absolute values; it con Frantz, 1971). Houston (1982) further demon
centrates on relations between specific parameters strated that direct digitization does not significant
within an individual patient, thus reflecting adap ly improve the conventional tracing technique.
tation of the facial components and allowing a Repeated measurements, therefore, still seem to be the
better understanding of the morphology of an only way of reducing the error of the method (9.3).
individual patient. However, the manner in which data are inter
preted is of even greater importance than either the
When cephalometrics is applied with the purpose of reproducibility of landmark location or the biolog
clarifying the anatomical basis for the various mal- ically based changes of the areas with respect to
occlusions, a precondition for the definition of a which structural superimpositions are defined
deviation is the existence of normative values. These (Baumrind et al, 1976, 1987a, 1987b, 1992a,
have been established on various reference groups. 1992b). For example, the validity of interpretations
Reference groups have generally been defined in two of individual cephalometric measurements is very
different ways: debatable. As a case in point, the literature on mea
1. The first is chosen to represent excellent occlu suring the sagittal jaw relationship will be discussed.
sion and facial proportion. For example, Downs A multitude of approaches have been taken to
(1948) defined the standards based on 25 subjects establish the anteroposterior relationship of the
who fulfilled these criteria. Tweed (1966) also jaws. All have, however, been subject to their own
defined mean values as representatives of desir weakness. It was pointed out by a number of
able profile, but it was soon realized that sub authors (Freeman, 1951; Riedel, 1957; Taylor,
groups had to be defined as well. Steiner's ideal 1969; Nanda, 1971; Jacobsen, 1975,1976; Bishara
measurements originated from a Hollywood etal, 1983; Hussels and Nanda, 1984) that the clas
starlet (Steiner, 1960). sical way of expressing the sagittal jaw relationship
2. The other type of normative values have been - namely the ANB angle - was influenced so much
developed from representative subgroups of pop by many biological variables (including the mor
ulations, including subjects with malocclusions. phology of the nasion area, the vertical dimensions
184
' Clinical Research Applications of Cephalometry
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9.3 Scattergram illustrating distribution of estimating errors of five radiographic landmarks, when 20 headfilms were evaluated by five
orthodontists. (Baumrind and Frantz. 1971; published with permission.)
185
of the face, the inclination of the anterior cranial predict the 'Wits' appraisal from the ANB angle and
base, and the inclination of the jaws) that its value found that the predictive value was very low, espe
in expressing the relative anteroposterior position is cially for the patients with a negative 'Wits' appraisal.
questionable (9.4). Jacobsen (1975) therefore intro Thayers (1990) analysed the effect of choosing
duced the 'Wits' appraisal, which related the jaws different occlusal planes, namely the bisected occlu
to the occlusal plane. Although this approach seems sal plane, the functional occlusal plane and the
more reasonable from a functional point of view, lower incisor occlusal plane. He found that the dif
it was also characterized by a number of weakness- ferent 'Wits' appraisals that were determined accor
es related to the fact that the occlusal plane can be ding to these planes were significantly different,
defined in a number of different ways. although highly correlated. Any of the planes could
The relationship between the above-mentioned be used, but none of the 'Wits' appraisals was very
two ways of expressing the sagittal jaw relationship closely correlated with the ANB. The highest corre
was studied by Rotberg et al (1980), who tried to lation to the ANB was found by the functional
9.4 Qualitative illustration of the effect on angle ANB of changing

the size of one parameter and holding the others constant. (A)
Opening rotation of the occlusal plane; (B) Increasing dento-
alveolar height; (C) Increasing distance N - B ; (D) Changing
anterior-posterior position of nasion. (From Hussels and Nanda,
1984; published with permission.)
W
\
\
A" ?
A «
N N
186
occlusal plane, accounting for approximately 5 0 %

of the total variation. The correlations between the
dental relationship expressed by the overjet and
'Wits' appraisal to the bisected occlusal plane 'Wits'
appraisal was 0.67, corresponding to a coefficient
of determination of approximately 4 0 % (9.5).
Apart from these rather confusing results, it
should not be forgotten that the reproducibility of
the functional occlusal plane is very low. Although
the bisected occlusal plane may have a higher repro
ducibility, it is thought-provoking that an error of
5° may change the 'Wits' appraisal by 3-6 mm,
depending on the vertical dimensions of the face.
Because of this, Williams and Melsen (1982) sug
gested the use of a constructed occlusal plane based
on a fixed relationship with the more reproducible
anterior cranial base.
It can be concluded that the use of cephalometric
analysis as part of the orthodontic diagnostic pro
cedures involves consequential uncertainties. As
early as 1964, Salzmann warned that using cephalo
metric standards that were drawn from subjects
with excellent occlusion in order to define treatment
objectives has no scientific justification. The only
certain thing about cephalometric measurements is
that they vary from patient t o patient. The range
of variation is more important than the mean on
which so-called standards are based.
When Han et al (1991) analysed the impact of the
cephalometric analysis on the treatment decision, it
was found that it was of very limited value. The lack
of validity of the cephalometric analysis as a diag
nostic measure for certain malocclusions has also
been pointed out by Vig (1991), who demonstrated
that the conclusion drawn on the basis of the same
cephalograms may vary according to the analysis
chosen.
In spite of these drawbacks, cephalograms still
serve an important purpose in the planning of treat
ment by establishing the point of reference in rela
tion to which the planned changes should be defined.
9.5 (A) Bisected occlusal plane (B!) drawn bisecting overlap of

distobuccal cusps of first permanent molars and incisors; (B)
Functional occlusal plane (FOP) drawn along molars and premolars;
(C) Lower incisor occlusal plane (LI) drawn from bisection of
distobuccal cusps of first permanent molars to tip of lower incisor.
(From Thayers, 1990; published with permission.)
187
LONGITUDINAL STUDIES OF UNTREATED clude the Steiner, Sassouni and D o w n s analyses.) In

PATIENTS the second method, cephalograms from pairs of time
points (or tracings from them) are physically super
The introduction of the cephalostat in the beginning imposed a n d aligned u p o n each other relative to
of the 1930s made it possible to follow the postna selected anatomical planes or lines (such as Anterior
tal development of the craniofacial skeleton. Cranial Base). Displacements of specifc structures
Longitudinal studies of the main tendencies and through time may then be expressed in a single mea
the variability of craniofacial growth through time surement. (9.7 s h o w s the use of this method for
in n o r m a l subjects a n d in subjects with craniofa multiple time points.)
cial anomalies and dentofacial malrelationships have Of the two strategies, the individual film methods
been carried o u t from multiple time point images. are simpler but the superimpositional methods are
Standards for growth patterns that characterize vari considerably m o r e powerful since they make it
ous specific growth types were developed on the basis possible to localize the specific sites of change much
of large longitudinal studies (Rioloetal, 1974; Broad- more precisely. A limitation of the superimpositional
bent et al, 1975; Popowich and T h o m p s o n , 1977). methods is the difficulty of aligning the anatomical
When the relationship between c e p h a l o g r a m s reference planes from different time points since
from t w o or m o r e time points is t o be evaluated, growth a n d t r e a t m e n t alter t h e planes themselves
two general strategies are available. Using the first t h r o u g h time. It is in this regard that the implant
strategy, each cephalogram is measured individu method of Bjork (1968) has provided such impor
ally and the differences are calculated by subtract tant insights. The pitchfork method of Johnston is
ing the values at one time point from the values at an i m p o r t a n t simplifying a p p r o a c h to the presen
a n o t h e r time point. (Examples of this method in tation of superimposition data.
9.6 (a) Example of a backward rotation

w i t h the centre at the condyles; (b) Exam
MATRIX ROTATION INTRAMATRIX ROTATION
ple of an i n t r a m a t r i x backward rotation
"PENDULUM MOVEMENT* resulting in resorption below the symphysis
BACKWARD
and apposition below the angle. Apposition
}
may occur at the chin point. The center of
r o t a t i o n is situated in the corpus. (From
B j o r k and Skieller, 1983; published with
permission.)
E="fj -APPOSITION
a b RSSJ-RESORPTION
9.7 (a) Tracing of three age-stages super

i m p o s e d o n s t r u c t u r e s in the anterior
cranial base. N o t e the forward rotation of
the mandible; (b) Mandibular tracing from
t h e same p a t i e n t s u p e r i m p o s e d on
reference structures of the corpus. Note
the intra-matrix rotation. (From Bjork and
Skieller, 1983; published with permission.)
188
The first longitudinal study stated that the growth rind etal, 1984). Asa conclusion of this disappoint
I pattern was genetically determined and established ing result, Baumrind (1991) suggested two strate
■ already at early age (Brodie, 1941). Attempts were gies for optimizing discussion making in lack of
I made to find the central point from which the facial growth prediction:
I skeleton was supposed to grow in a linear manner • sharpening the focus on the consequences of
I growing along radii (Broadbent et al, 1975; prognostic errors; and
I Bergersen, 1966). When the implant method was • augmenting the amount of data available on a
I introduced into the study of the human facial stepwise basis through time before making irre
skeleton (Bjork 1968), it became possible to differ- versible commitments.
I entiate displacement through sutural and condylar
I growth from modeling by resorption and apposi- He also points out the need for scientifically based
I tion. Therefore, it was possible to describe the dif- clinical decision making within orthodontics.
I ferentiated growth pattern that leads to rotation In relation to treatment of most patients under
[ (especially of the mandible, but also to some degree going orthognathic surgery, normally no growth is
I of the maxilla). The myth of linear growth was occurring, and the cephalometric predictions can
I thereby rejected (9.6, 9.7) (Bjork and Skieller, 1983). consequently usually be made on firmer ground.
Cephalometric analyses have also been developed
specifically for planning the treatment of orthog-
GROWTH PREDICTION natic surgery patients. However, when comparison
of five currently used analyses was performed on
I Orthodontists find it satisfying to be able to predict patients presenting dentofacial deformities, it
I growth, especially since a large part of orthodon demonstrated considerable inconsistency, both in
tic treatment is aimed at changing the magnitude or the diagnosis and in the suggested surgery plan
the direction of growth. A considerable number of (Wylieetal, 1987).
cephalometric studies have been focused on devel
oping algorithms for the prediction of craniofacial Conclusions
growth with respect to various morphologic para The above-mentioned difficulties in interpretation
meters from multiple or single time point images. of cephalometric values emphasize the need for
Growth prediction has been part of much ortho reconsideration of the use of cephalometric analysis
dontic treatment planning in young children. The in diagnosis and as the basis for orthodontic treat
approach has been highly discussed and some ment planning. It is, therefore, suggested that treat
methods even have been commercialized (Ricketts ment should be planned on the basis of the pre-
et al, 1979). The controversy about prediction, treatment data of the individual case rather than in
which almost separates orthodontists into two relation to predetermined norms. This implies that
groups, is often a matter of interpretation, because a treatment plan should also include the planned
the ability to predict growth on a group basis is cephalometric changes in both the sagittal and
often mistaken for the ability to predict growth of vertical directions. Only by expressing the treatment
I the individual patient. The correlation matrices used goal in this way is it possible to evaluate the efficacy
lor the generation of statistical predictors are partly of a treatment.
determined by topographic correlations and the bio
logical meaningful correlation is weak. INVESTIGATIONS A M O N G TREATED
Therefore, it is not possible to explain for indi SUBJECTS
vidual patients a sufficient part of the total variation
to be clinically useful. The prediction on a group General principles
basis is, on the other hand, very precise and increas Since it is the purpose of orthodontic treatment to
es its precision with augmented group size, since the correct a malocclusion, it is important to possess
standard error of the mean is a product of the group information on the efficacy of the various treatment
size. In one empirical study, even highly skilled and modalities. The majority of cephalometric research
experienced orthodontists assisted by computerized projects regarding the treatment effect are done ret
measurements were not able to differentiate poten rospectively. Available studies include major inves
tial forward rotators from potential backward tigations of predefined individuals chosen as being
rotators significantly better than by chance (Baum- representative for certain subgroups defined by age,
189
race, or specific malocclusions as well as descrip cussed in detail by Norton and Melsen (1991) and
tions of few or even single treated cases. have led to a long series of reports on controversies
The need for knowledge on the influence of treat regarding the effect of these appliances. Most
ment on all types of malocclusion is obvious. The authors who describe treatment effect do not take
motive for carrying out the above-mentioned into consideration any of the above-mentioned ques
research is, therefore, easy to comprehend. tions. Even when experimental and control patients
However, there is still a need for problem-driven are matched with regard to certain essential vari
clinical research. Depending on the individual treat ables, so-called identical human individuals can be
ment modality, different questions can be asked. anticipated to react differently. The use of monozy-
For example, with regard to functional appliances gotic twins treated differently is not realistic and the
it would be natural to ask the following questions: use of animal studies has other drawbacks:
• no animal species available for study have a mas
1. Does this mode of therapy really improve the ticatory system that closely resembles the human
skeletal relationship? masticatory system;
2. Which clinical parameters are influenced the • it is not possible to simulate the way the appli
most? ance is worn; and
3. Is the effect clinically significant? • the animals are not treated for a malocclusion.
4. Is the result prone to relapse or will normal
growth catch up with the temporary advantage? When evaluating the effect of fixed appliances, it
5. Are there easier ways to achieve similar results? is a precondition that the force system should be
6. What are the factors involved in provoking the known in detail in three dimensions, that the treat
treatment result? ment goal should be likewise defined, and that the
7. Does the abundant cephalometric research within efficacy should be expressed as the degree of coin
this category then gradually clarify the effect of cidence between the predicted and the observed
all available treatment modalities? If not, why? result. Provided that the selection of biomechani-
cal system is correct for a given problem, lack of
Moreover, in evaluating the results of any clinical efficacy could then be accounted for by biological
study, the one transcendent question that has to be variation. A description of a treatment result does
asked is: Were the processes of sampling and mea not provide this information, since a treatment
surement sufficiently free of bias to allow meaning result is an interaction between the biological envi
ful conclusions to be drawn? ronment and the force system generated. Only if the
latter is known, and only if the impact of the force
Evaluation of treatment effects system overwhelms that of the biological variation,
In relation to fixed appliances, it would be relevant can the treatment effect be predicted on an individ
to ask, for example, to what degree the observed ual basis. The effect of an appliance described by
tooth movement corresponds to the expected dis comparing the means of the treated and an untreat
placement, and whether there is a fundamental dif ed group does not predict what eventual effect the
ference between the effect of the functional appliance will have on the patient sitting in the
appliance and that of the fixed appliance. While the dental office right now. Treatment effect should be
latter can be tested in vitro together with the descrip evaluated by comparison of treatment goals, which
tion of the force systems developed (Burstone, 1982; are defined by the orthodontist on the basis of pre
Melsen, 1991), the same cannot be done with the dicted growth changes combined with a forecast of
functional appliances as their effect is entirely depen treatment changes (the so-called VTO - visualized
dent on their interaction with the biological envi treatment objective) and the treatment result.
ronment. The difference between the anticipated and the
The shortcomings in relation to the evaluation of obtained treatment result reflects the efficacy of a
the effect of functional appliances have been dis treatment modality (9.8).
190
Clinical Research Applications ofCephalometry
FINITE E L E M E N T ANALYSIS
During the 1980s, the finite element method was

applied as a new approach to the analysis of
cephalograms (Moss et al, 1985). Finite Element
Analysis is an engineering method that uses partial
differential equations to interpolate loading values
for intermediate points in irregular structures by
dividing the structures into sets of regular geomet
ric shapes (in the simplest case, into triangles).
The introduction of this new method does not,
however, solve the problems related to prediction of
growth changes. The following should be taken into
consideration:
1. The method requires accurate and precise mea
surement of the known landmarks in the system.
As used by Mossetal (1985) and Bookstein et al
(1985), the landmark location procedures are just
as crude and error-prone as those of convention
al cephalometrics. In fact, the landmarks used are
obtained by conventional cephalometric
9.8 Comparison between planned and obtained result of
methods, usually without replication.
orthodontic treatment. The planned root inclination was not 2. The utility of Finite Element Analysis in the
reached completely. analysis of growth and development processes
has not been tested except to compare its findings
with those of conventional methods. In other
Conclusions words, the idea that the method is useful is a
When relating to growing patients the outcome of hypothesis without a test. Indeed, it appears to be
a treatment is partly a product of growth and an untestable hypothesis.
development and partly a product of the impact of 3. As used by Bookstein et al (1985) and Moss et al
treatment. Since it is not possible to predict growth (1985), the nodes surrounding the elements
on an individual basis, the efficacy of treatment for straddle sutures and even extend from the cal-
young patients can be expressed only on a popula varium to the mandible. This violates the usual
tion basis, as individual variation in growth is part assumption of Finite Element Analysis that within
of the treatment result. In adult patients, this each element the structure is homogeneous.
problem does not exist, and this simplifies efficacy 4. Most importantly, there is a fundamental ques
studies. Such studies have already been done in tion about the propriety of applying a mathe
orthognatic surgery, where regression equations matical model that was, in essence, developed to
have been developed that relate surgical plans to the measure strain and deflection of structures under
immediate and long-term outcome of surgery. mechanical loads to the processes of develop
Similar research has thus far failed completely in mental biology in which mechanical loading is
orthodontics. minimal or non-existent. Aside from muscle
The multiplicity of treatment reports available forces, which are intermittent and irregular and
should be used as a basis for the generation of which no one has ever even claimed to account
hypotheses on treatment effect, and prospective for in the skull by Finite Element Analysis, the
studies should be planned to test these hypotheses. only deflecting loads of importance in biology are
Only then will orthodontics be on the way from associated with gravity and they are not modelled
being an art to becoming a science. in Finite Element Analysis schemes. It may be
191
noted particularly that the effects of gravity are ADVANTAGES OF CEPHALOMETRY

highly dependent on orientation, and this quite
contradicts the emphasis of Bookstein and Moss Cephalometry has been, and remains to a very large
on orientation-independent analytic schemes. degree, the only available method that permits the
investigation of the spatial relationships between
cranial structures and between dental and surface
ADVANTAGES A N D LIMITATIONS structures (9.9) (Graber, 1966). Study casts give
OF CEPHALOMETRY IN RESEARCH more complete information on dental structures and
APPLICATION facial photographs yield more complete information
on surface features, but only cephalometric images
Cephalometry, in common with other diagnostic yield accurate information on the spatial relation
and descriptive modalities, has both advantages and ships between surface structures and deep struc
limitations, some of which are related to the tures. Computed tomography, magnetic resonance
cephalometric analysis and have been discussed imaging and ultrasound imaging also permit simul
above. The advantages and disadvantages of taneous mapping of surface and internal structures
cephalometry are interpenetrating. to some degree. However, each of these more
modern modalities, at least for the present, involves
higher economic and/or physiologic costs and yields
information of lower spatial resolution in the
sagittal and frontal projections, which are the main
concern of clinical craniofacial biology.
Therefore, it seems fair to say that, compared to
other available methods, cephalometrics is relative
ly non-invasive and non-destructive, thus producing
a relatively high information yield at relatively low
physiologic cost. Cephalometrics has also rendered
serial assessments of growth possible and permitted
investigators to monitor the ongoing processes of
treatment and growth in vivo.
Unlike diagnostic procedures such as calliper
measurement, palpation, auscultation, probing, and
oral interview, additional advantages stem from the
fact that cephalometrics produces tangible physical
records that are relatively permanent. The same sets
of cephalograms can be used for testing different
theories and hypotheses. Future cephalometric
research will be much increased in power and effi
ciency if different subsets of co-ordinate data can be
acquired sequentially from the same sets of cephalo
grams by different investigators. Furthermore, since
cephalograms are essentially two dimensional, they
are relatively easy to store, reproduce and transport.
LIMITATIONS OF CEPHALOMETRY
The limitations of cephalometry derive essentially

from the fact that most of the advantages noted
above are relative rather than absolute. The most
9.9 Relation between facial and dental structures as illustrated by important limitation is the fact that, although the
Graber. (From Graber, 1966; published with permission.) information yield of cephalograms can be very high
192
>mpared to their physiologic costs, the physiolog standardization in current image acquisition and
ic costs in the form of radiation exposure are real measurement procedures.
ind must be fully taken into account each time a A further complication is the inherent ambigui
cephalogram is generated. Therefore, in contempo ty in locating anatomical landmarks and surfaces on
rary use it is considered unacceptable to generate X-ray images, since the images lack hard edges,
cephalograms unless they are diagnostically and shadows, and well-defined outlines. While cephalo
therapeutically desirable in the interests of the par grams themselves are two dimensional, the struc
ticular patient being examined. tures being examined are three dimensional. This
In addition to the problem of radiation exposure, contradiction leads to differential projective dis
cephalometrics is characterized by a number of tech placement of anatomical structures lying at differ
nical limitations, some of which have been men ent planes within the head. The fact that all
tioned above. The absence of anatomical references structures lying along any given ray between the X-
whose shape and location remain constant through ray source and the film are imaged at the same point
time presents a serious complication to investigators on the film (9,10) makes it physically impossible to
and clinicians wishing to make comparisons locate the positions of structures accurately even in
between images generated at different timepoints. two dimensions in the absence of information about
This problem is complicated by the lack of sufficient the third dimension.
9.10 Geometry of a norma lateralis X-ray image. LI represents

the anode or focal spot. Notice that points A, B and C will all be
projected upon the film surface at the same point P even though
they are at different levels within the skull.
193
Although several groups of investigators are plane. Such corrections, however, involve highly
attempting to produce true three-dimensional co questionable assumptions of bilateral symmetry and
ordinate information from paired projected X-ray are, therefore, only approximations. Moreover, the
images (9.11, 9.12), such methods are not yet fact that three-dimensional information is missing
standard. in conventional cephalograms makes it categorical
In most contemporary cephalometric analyses, ly impossible to integrate (or merge) information
lateral (sagittal) projections are used almost exclu from cephalograms with information from three-
sively and it is customary to make partial corrections dimensional records like study casts without sub
for projection errors by averaging the projections of stantial measurement errors.
bilaterally paired structures upon the midsagittal
LI
1
1
1
1
1
1
1
1
J-ff 1 fc
9.1 I The solution of Broadbenr and Hofrath to the problem identified in 9.10 was to generate a norma frontalis image projected upon a
second film oriented at right angles t o the norma lateralis film. Information f r o m this second film facilitates the identification of the three-
dimensional location of points A , B and C. The problem w i t h this method, however, has been that most of the anatomical points of infor
mation for craniofacial biologists cannot be seen unambiguously o n both the lateralis and frontalis films. For this reason, the quantitative
use of paired norma lateralis and norma frontalis films has never been popular.
194
Clinical Research Applications ofCephalometry
GUIDELINES FOR PROPER

CEPHALOMETRIC RESEARCH
APPLICATIONS
RESEARCH DESIGN
The use of cephalograms as sources of research data

involves an important paradox, namely that each
cephalogram is a static two-dimensional projection
of a dynamically changing three-dimensional object.
This means that individual cephalograms by their
nature lose all information about biological process
es (i.e. development) as well as almost all informa
tion about three-dimensional shape. On the other
hand, not withstanding their limitations, cephalo
grams are by far the best standardized records of
craniofacial development that are currently avail
able. A number of investigators during the 1960s
and 1970s opted to acquire large collections of
loosely defined discrete landmarks from cephalo
grams in the belief that they could extract all the
relevant information for later use. The 1977
landmark subset of Walker et al represented one
notable example of such a strategy (Sakscna et al,
1987).
Carrying the idea of preserving all information
a bit further, Bookstein et al (1985) emphasized that
any set of simple two-dimensional co-ordinates loses
information about shape because it has discarded
9.12 An alternative approach is to generate a second image in directional data on the associations among land
what is called the coplanar mode. In this approach (which is marks that lie along any given anatomical edge or
modelled after the aerial and satellite mapping techniques) the surface. This concern about loss of information
second image is projected on a film located in the same orienta stems from the failure to distinguish between two
tion as the first film but from an anode located at L3. In this
separate roles of cephalograms in craniofacial
method, unique location of points A, B and C is simplified but
some of the mathematical power of the Broadbent/Hofrath research:
solution is sacrificed. • as global records, for which purpose one would
like them to contain as much information as
possible; and
• as data sources from which one would wish to be
able to extract relatively small subsets of data
appropriate to specific questions as efficiently as
possible.
The appropriateness of this statement is easily

demonstrated. Modern digital scanners can readily
translate a conventional analogue 10 inch x 12 inch
195
cephalogram of roughly 6 million to 8 million co data can be acquired sequentially from the same
ordinate pairs. The total information content of a set of cephalograms by different investigators.
cephalogram is a somewhat larger multiple of this
number, since it includes all the co-ordinate point If advantage is to be taken of all the information
pairs plus all the interactions among them, taking inherent in the cephalograms already produced, the
any number of points at a time. It is obvious that craniofacial research establishment needs to develop
any attempt to convert all the information in a mechanisms for making access to original records
cephalogram into data for use in numerical and sta (or their electronic equivalents) generally available
tistical analysis without losing any is both absurd to qualified investigators at different locations
and impossible. throughout the world. In the past, the possibility of
The task of intelligent problem-driven research is this kind of research approach seemed a fantasy and
to abstract from the background (i.e. convert into a pipe dream, but recent development in electronic
data) the most meaningful information, a process image transfer has now made it entirely practicable.
that inherently involves leaving vastly larger Currently, work on the construction images,
amounts of less important information behind. together with an associated numerical data base, is
Obviously, there are important differences of under way at several institutions (Baumrind, 1993),
opinion among clinicians and investigators con and this was a major subject of discussion at a recent
cerning which subsets of the total information in American Association of Orthodontist Orthodontic
cephalograms are most meaningful. These differ Educators 1 Workshop (1991).
ences can be reconciled by making high-quality In the area of shared records research, several
duplicates of the original image available to multiple caveats need to be agreed upon:
qualified investigators together with a mechanism 1. In order for it to be possible to compare different
that permits them to select subsets of data of their subsets of data acquired from a given cephalo
choice. The data obtained by alternative strategies gram in the course of testing different concepts,
should be integrated into a common data base. all the subsets of landmark data from each image
must share a common and unambiguous geo
General principles metric frame of reference, which can be achieved
Several general principles for cephalometric research by marking or punching small crosses or dots at
emerge from these considerations. the corners of each original image.
1. There is a profound need to distinguish between 2. Protocols need to be developed in order to
records and data as well as between cephalo- prevent uncontrolled browsing through shared
grams themselves and the sets of co-ordinate records bases. In the absence of such controls,
values extracted from them. Obviously, the premature ad hoc browsing could make it impos
primary information resides in the cephalograms, sible to use the records and data in an unbiased
whereas the co-ordinate values derived from them manner in later hypothesis testing studies
are secondary and are clearly heir to additional (Armitage and Berry, 1987).
subjective and objective acquisition errors. 3. It is particularly important that the profession
Investigators must always remember that records should arrange procedures to replicate electron
come before data. ically the remaining longitudinal records sets of
2. It is important that cephalometric research is untreated control subjects that were collected in
problem driven. This is to say that co-ordinate Europe and North America in the period between
data should be acquired from cephalograms selec 1920 and 1960. These images are literally irre
tively based on specific theories, hypotheses or placeable, since it would be inappropriate and
perceived clinical or biological problems, rather unethical to attempt to generate radiographic
than on the basis of unstructured fishing expe images of untreated normal subjects now. The
ditions. window of time for this image-capture enterprise
3. Consequential advantages exist when the same is quite short, since the existing records sets are
sets of cephalograms can be used for testing dif reaching the end of their archival life and in
ferent theories or hypotheses. Future cephalo addition they are tending to become physically
metric research will be much improved in power dispersed and unavailable (Hunter et al, 1993).
and efficiency if different subsets of co-ordinate Hence, these procedures need to be arranged in
the very near future.
196
\
I IMAGE ACQUISITION spective image manipulation can ever fully recover
from technical errors made at the image-generation
Risk-benefit considerations stage, manufacturer's instructions on processing
I Craniofacial investigators must place in perspective should be scrupulously observed. Particularly
■ the physiological costs of image acquisition. All i m p o r t a n t in this regard are the t e m p e r a t u r e and
I ionizing radiation represents a health hazard and freshness of developing and freezing solutions and
I dinicians and investigators have an absolute respon- the thoroughness of post-fixation washing.
I ability to minimize radiation exposure to patients Beyond these specific suggestions, users of
I and staff. O n the other h a n d , the orthodontic spe- roentgenographic cephalograms should familiarize
I ciality needs to develop a realistic perspective about themselves with the basic physical characteristics of
I the risk-benefit considerations involved in roent- X-ray images (such as contrast, noise, and dynamic
I genographic cephalometry. range) by consulting the appropriate technical lit
In brief, the radiation risks from cephalometry erature presented in previous chapters of this text
I are real but very small. T h e fact is t h a t the use of book.
I intensifying screens, which is routine in c e p h a l o -
I merries nowadays, decreases exposures dramatical Standardization of i m a g e g e o m e t r y
l y as compared to non-screen techniques. The O n e of the greatest contributions of the early
I cephalometric dose of 2 2 - 4 0 mr (millirems) per film cephalometricians both in Europe and the USA was
Iis very low in the spectrum of medical diagnostic the recognition that if cephalograms were t o be
I procedures. Without alarming the public a b o u t the measured consistently, the head must be placed in a
I use of standard dental radiologic methods, we have known relationship to the X-ray source and the film
I to find tactful ways of informing our colleagues that cassette.
I the average radiation dose per headfilm is only mar- Most modern users take cephalostats for granted.
I ginally greater t h a n that for a single intraoral or However, these instruments are very important, since
I bite-wing film. T h e response to the recognition that they provide a level of precision in positioning the
I radiographic m e t h o d s are not totally w i t h o u t risk subject that surpasses that of any other standard diag
I should not be their abandonment in favour of vastly nostic radiologic procedure in dentistry or medicine.
I less meaningful methods (e.g. measuring facial pho- In the USA, t h e X-ray source is generally posi
I tographs), but rather a careful optimization of the tioned 5 feet (150 cm) from the patient's midsagit-
I radiographic m e t h o d s themselves. Similarly, with tal plane. In Europe, this may differ considerably.
I regard to the experimental use of metal implants of When a lateral cephalogram is taken, the central ray
I the type used by Bjork, we have to reassure the passes through the ear-rods along the porion-porion
I public that no u n t o w a r d effects have ever been axis. When a frontal cephalogram is taken, the line
I reported following the use of these physical markers between the ear-rods lies parallel t o the film plane
I and that the information yield to the public from and perpendicular to the central ray (with the
I their use has been very considerable. Additional lon- subject facing the film). It is important to note that
I gitudinal studies of the effects of o r t h o d o n t i c and all conventional cephalometric measurement and
I surgical treatments in the craniofacial region refer analysis systems assume that these conditions have
enced to implants should be encouraged. been met. If they are met, valid comparisons can be
made between images generated on different X-ray
Maximizing information yield machines. However, if they a r e not maintained,
I Clinicians and investigators have a professional and comparisons between images will be flawed, even if
[ethical responsibility to maximize the information the images are generated on the same machine.
I yield per unit of radiation. M o r e attention needs to In the early years of roentgenographic cephalom
I be given to the design of standardized soft tissue etry, the available X-ray machines had very modest
[shields and technicians must be carefully trained to performance characteristics with low KV output. In
[position them in such a way as t o optimize the order to improve image quality, it became the con
[imaging of soft tissue and hard tissue profile land vention to position the film cassette as close to the
marks. Unless care is exercised, optimal imaging of subject's face as possible, thus reducing the effects
[ the soft tissue profile may be achieved only at the of the air g a p between subject and film. As patients
■ cost of losing hard tissue information. Since expe grew, successive images were generated with the film
dience has demonstrated t h a t n o a m o u n t of retro- plane at different distances from the system origin,
197
resulting in different enlargement factors between IMAGE DETERIORATION A N D LOSS

films and making them no longer comparable in
scale. In theory, the several films for a single subject The failure to protect images from deterioration or
could be calibrated with respect to each other by loss has been a very major source of information
comparing the images of a scale mounted on the loss in craniofacial biology. X-ray films and sets of
cephalostat and projected onto the film surface. In films can deteriorate physically, and collections may
practice, this system was cumbersome and inaccu become lost or dispersed because of loss of interest,
rate and the corrections were rarely made. control, or financial resources.
Modern X-ray systems are sufficiently powerful At the level of physical deterioration, there are
not to require positioning of the film against the a few points to be made. Some are technical and
subject's face, but unfortunately the manufacturing some are embarrassingly obvious. At the technical
conventions continue to favour variable distances level, one of the main reasons for X-ray film dete
between the cephalostat and the film plane. A new rioration over time is the failure to wash the films
convention is, therefore, needed to fix the distance properly at the time of processing. This problem has
between the cephalostat origin and the film plane. become more severe since the advent of the 90-
Until such a convention is adopted, each investiga second automatic film processor. The tell-tale sign
tor should at least keep the cephalostat-film is the smell of acetic acid when one enters the room
distance constant and known within his or her own in which a collection is stored. The treatment is to
facility. When interpreting images generated with carefully rewash the films, but the fact is that by the
constant and correct source-subject distances, but time the odour is detected, much of the damage has
with variable subject-film distances, clinicians and been done. As in other areas, prevention is probably
investigators should be aware that angular rela the best cure and the profession should establish
tionships and ratios between linear measurements higher standards for washing and rewashing films
are independent of the subject-film distance. at the time they are originally processed.
Another gap in our conventions involves the Other major steps to attenuate the deterioration
direction the subject is facing when lateral cephalo- of physical images are storage in a clean, cool, dry,
grams are generated. In the USA, the subject is posi and smoke-free environment and assuring that no
tioned with the left side of his face nearer the film, water supply, food, or drink is present in the rooms
while in Europe very often the right side of the face in which X-ray images are examined. One should
is nearest the film. Obviously either convention is also be sure that X-ray cephalometric films are filed
satisfactory, but care should be taken not to mix the in suitable archival plastic covers or at least that they
conventions in the same subject when, for example, are not stored in coverings that can accelerate their
new X-ray equipment is acquired. Paired structures deterioration. The use of cotton gloves while
are always enlarged differentially in lateral cephalo- handling films is also desirable although in the
grams with the side nearest the X-ray source author's experience it is less important than the
enlarged more than the equivalent structure nearer grosser sources of image deterioration just noted.
the film surface. Therefore, in the USA convention, The most dramatic and acute loss of information
structures on the right side are always enlarged more from images occurs when the images themselves are
than those on the left side; in Europe, the relation lost. This may occur through misfiling or by mis
ship is reversed. Unless a subject is perfectly sym appropriation, and any substantial collection should
metrical, reversing the orientation of a film by be in the charge of a responsible curator who has
turning it over will not correct this disparity. appropriate oversight authority. It needs to be
Our final point on image geometry involves the acknowledged that one important source of film
question of natural head position. It is a demon losses from university clinics is the departing
strable fact that any technique which generates graduate who cannot resist the temptation to appro
cephalograms with the ear-rods disengaged will be priate records of favourite cases for later personal
subject to increased measurement errors because the use. Even more important is the general dissolution
central ray path will inevitably deviate from the and abandonment of a number of longitudinal
porion-porion axis. However, for certain purposes, image bases laboriously collected in various growth
investigators may accept this deficit, but the reality studies during the period between 1930 and 1970.
of the increase in method error due to an eventual Because of lack of curators and even minimal
asvmmetrv should be taken into consideration. funding for maintenance, several of these invaluable
198
collections have already been dispersed and lost, Baumrind S, Korn EL, Ben-Bassat Y, West EE
while others are stored inaccessibly under margin (1987b) The quantitation of maxillary remodelling.
ally or completely unsatisfactory conditions. 2. Masking of remodelling effects when an anatom
It is necessary for society and the orthodontic spe ical method of superimposition is used in the
ciality to recognize that the storage of information absence of metallic implants. Am ] Orthod
has very real and ongoing costs, even if those costs 91:463-74.
are very much lower than the original cost-effective
optoelectronic storage of image information in Baumrind S, Korn EL, West EE (1984) Prediction of
digital form at the present. mandibular rotation: An empirical test of clinician
performance. Am J Orthod 86:371-85.
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202
[CHAPTER 10
Cephalometric Assessment of Craniocervical Angulation,

Pharyngeal Relationships, Soft Palate Dimensions,
Hyoid Bone and Tongue Positions
Athanasios E Athanasiou, Moschos Papadopoulos, Michael Lagoudakis
and Panos Goumas
INTRODUCTION anatomy and dentofacial build. Gresham and

Smithells (1954) found a longer face and an
Traditional roentgencephalometry is used exten increased prevalence of class II malocclusion in a
sively in clinical orthodontics to quantify dental, group of subjects with 'poor neck posture 1 .
skeletal, and soft tissue relationships of the cranio- According to Bench (1963), vertical growth of the
:
facial complex before the initiation of therapy. Less face after puberty has a high correlation with neck
ioften (and usually in clinical research), cephalome- growth, so that patients with dolicocephalic faces
rryisa useful tool for assessing craniocervical angu- often have a tendency for the cervical column to be
Jation, pharyngeal relationships, soft palate straight and long, whereas brachycephalic patients
dimensions, and hyoid bone and rongue positions. often have a curved cervical column. In line with this
With regard to these applications, the purposes concept, it has been recently suggested by Houston
of the cephalometric investigations can be divided (1988) that the growth of the cervical column is the
into two main categories. The first group consists of primary factor determining growth of anterior face
studies that aim to test hypotheses on possible asso height.
ciations between craniocervical angulation, pha- The atlas has been considered of particular
jryngeal relationships, soft palate dimensions, and interest to the orthodontist. Von Treuenfels (1981)
hyoid bone and tongue positions, and hypotheses observed that the inclination of the atlas is associ
on the growth, development, and morphology of the ated with the sagittal jaw position in that the ventral
craniofacial complex. The second category of arch of the atlas attains a more cranial position in
studies consists of investigations that aim to test the progenic than in orthogenic patients. Kylamarkula
influence of these biological variables by non-phys and Huggare (1985) found a correlation between
iologic or pathologic conditions and their treatment head posture and morphology of the atlas, partic
(i.e. respiratory problems, sleep disorders, blindness, ularly with regard to the vertical dimension of the
orthognathic surgery). atlas dorsal arch.
In the othodontic literature, there are a number It has been shown that obstructions of the upper
[of studies of associations between head posture and airway lead to changes in neuromuscular patterns,
Identofacial build (Schwarz, 1928; Solow and thus influencing the posture of neck, head, man
:Tallgren, 1976; Marcotte, 1981; Solow and dible, tongue, soft palate, and lips (Vig et al, 1981;
j&rsbaek-Nielsen, 1986; Hellsing et al, 1987; Show- Miller et al, 1984; Solow et al, 1984; Vagervik et al,
fry etal, 1987). 1984; Hellsing et al, 1986; Behlfelt and Linder-
Bjork (1955, 1960, 1961), in his roentgen- Aronson, 1988; Wenzel et al, 1988).
;phalometric studies of individual variations in The size of the nasopharyngeal airway and the
[craniofacial growth, drew attention to divergences adenoids on the posterior pharyngeal wall may be
head posture that were related to different facial assessed by clinical inspection (posterior rhinoscopy).
(types. However, in children this inspection may be difficult
The anatomy and growth of the cervical verte to carry out and the examination is, therefore, of
brae has attracted attention since several authors limited value. Although the pharynx can also be
proposed developmental associations between vari visualized by several techniques, including cinera-
ables that could be indicative of cervicovertebral diography (Borowiecki et al, 1978), fiberoptic bron-
203
choscopy, acoustic reflectance (Fredberg et al, produced by forward and downward tilting of the
1980), and forced expiratory manoeuvres (Haponik head and neck with an unchanged craniocervical
et al, 1981), the techniques of CT scanning (Suratt angulation.
et al, 1983; Haponik et al, 1983) and lateral Gross changes in tongue position can be assessed
cephlometry (Riley et al, 1983; Rivlin et al, 1984) by analysing changes of hyoid bone position, which
are more commonly used. is determined by the conjoint action of the suprahy-
Radiologic demonstration of the adenoids and oid and infrahyoid muscles and the resistance
the nasopharyngeal airway was first made by provided by the elastic membranes of the larynx and
Grandy (1925), and since then many publications the trachea (Fromm and Lundbcrg, 1970;
have dealt with this method of examination Gustavsson et al, 1972; Bibby and Preston, 1981)-
(Goldmann and Bachmann, 1958; Johannesson, However, it has been stated that linear measure
1968; Capitonio and Kirkpatric, 1970; Linder- ments on the hyoid bone of less than 2.0 mm can be
Aronson, 1970; Lindcr Aronson and Henrikson, considered within the realm of physiologic variation
1973; Hibbert and Whitehouse, 1978). (Stepovich, 1965).
Although the obvious limitations of any two- Studies have shown that changes in hyoid bone
dimensional cephalometric study have been clearly position are related to changes in mandibular
recognized, several authors have quantified specific position (Takagi et al, 1967; Fromm and Lundberg,
airway parameters in order to evaluate nasopha 1970; Graber, 1978; Opdebeeck et al, 1978;
ryngeal obstruction, the position of the base of the Adamidis and Spyropoulos, 1983) and that the
tongue, and the pharyngeal relationships (Linder- hyoid bone adapts to anteroposterior changes in
Aronson, 1979; Guilleminault et al, 1984; Solow et head position (Gustavsson et al, 1972).
al, 1984). If certain technical requirements are ful Review of the literature suggests that a careful
filled, lateral cephalometry can provide some useful analysis of craniocervical relations in studies of
information in the estimation of tongue and hyoid bone can improve our understanding of the
nasopharynx volume (Pae et al, 1989). Nevertheless, behaviour of the tongue and hyoid bone during
it is still a matter of debate which radiographic growth and aging of the craniofacial complex
dimensions are best correlated to clinical symptoms (Tallgren and Solow, 1987). Studies of the relation
(Sorensen et al, 1980). ship of the hyoid bone to the facial skeleton and the
Methodological studies on the validity of cervical column have indicated that the hyocervi-
cephalometry have found statistically significant cal relationship is more stable than the relationship
correlations between the following variables: of the hyoid to the skull and the mandible (Carlsoo
• the posterior airway space (as measured by and l.eijon, 1960; Takagi et al; 1967, Fromm and
cephalometry) with the volume of the pharyngeal Lundberg, 1970; Opdebeeck et al, 1978; Bibby and
airway (estimated with the use of three-dimen Preston, 1981). This finding has also been confirmed
sional CT scans) (Riley and Powell, 1990); by the longitudinal studies on denture wearers,
• the small size of the nasopharyngeal airway with which have shown that changes in hyoid position
snoring (Sorensen et al, 1980); are co-ordinated with changes both in mandibular
• measurements of the airway and the depth of soft position and in head and cervical posture. This
tissue of the posterior wall with the nasal respi suggests that changes of hyoid bone position should
ratory resistance (Sorensen et al, 1980); and be related to changes in both mandibular inclination
• a cephalometric variable of the size of the airway and head and cervical posture (Tallgren et al, 1983;
(measured as the shortest distance from the ade Tallgren and Solow, 1984).
noidal mass to the posterior wall of the anthrum) With regard to most of the variables that are used
and the size of the adenoids (assessed surgically) to assess the position of the hyoid bone, no signifi
(Hibbert and Whitehouse, 1978). cant relationships have been found to exist between
patients with class 1, II or III types of malocclusiom
Because vision is one of the factors involved in the (Grant, 1959) or between patients with open bite
control of head posture, Fjellvang and Solow (1986) and normals (Andersen, 1963; Subtenly and
evaluated how blindness influences the posture of Sakuda, 1964; Haralabakis et al, 1993). On the
the head and neck. It was found that there was a dif other hand, Tallgren and Solow (1987) found that
ferent head posture in the blind group, which was a large hyomandibular distance is associated with a
204
Cephalometric Assessment
large mandibular inclination and that the mean subject looking straight into a mirror - the mirror
vertical distances of the hyoid bone to the upper position (Solow and Tallgren, 1971).
face, the mandible, and the cervical column are sig The standing position, which has been more often
nificantly greater in older age groups. suggested, is the orthoposition, defined by Molhave
In this chapter, cephalometric assessment of cran- (1958) as the intention position from standing to
bcervical angulation, pharyngeal relationships, soft walking. According to Solow and Tallgren (1971),
palate dimensions, hyoid bone position, and tongue before the positioning of the subject in the cephalo-
position is addressed with regard to: stat, the desired body posture, namely the orthopo
• the technical requirements chat should be fulfilled sition, can be obtained by letting the subject walk
in order to obtain meaningful cephalograms; slightly on the spot. The attainment of the self-
• the landmarks, reference lines, and variables balance head position can be facilitated by letting
described in the literature; and the subject tilt the head forwards and backwards
• some norms of head posture. with decreasing amplitude until he feels that a
natural head balance has been reached. The subject
can then be asked to assume the rehearsed body and
TECHNICAL REQUIREMENTS head position below the raised headholder of the
cephalometer so that both external auditory
In order to obtain optimal cephalometric assessment meatuses correspond to the vertical plane of the ear-
ofcraniocervical angulation, pharyngeal relation rods. If the obtained position is not satisfactory, this
ships, hyoid bone position, and tongue position, it routine can be repeated.
has been strongly advocated that the lateral head- In order to obtain the mirror position, the same
plates should be taken with the teeth in occlusion procedure for controlling the body posture can be
and the subject sitting upright (Tallgren, 1957; used; then the subject is asked to assume a conve
Moorrees, 1985) or standing upright (Solow and nient head position while looking straight into his
Tallgren, 1971) with the head and cervical column or her eyes in a mirror placed on the wall in front of
in the natural position (Siersbaek-Nielsen and the plane of the ear-rods.
Solow, 1982). In some special cases lateral cephalo In order to maximize reproducibility and stan
grams can be taken in the supine position (Pae et al, dardization of the radiographs in natural head
1994). Natural head position is the relationship of position, other methods have been presented. These
the head to the true vertical (Cole, 1988); in methods propose the use of a spirit level device
cephalometric radiographs it is a standardized ori attached to the side of the head using a double-sided
entation of the head in space. Since the natural head sticky-back square (Showfery et al, 1983) or similar
position uses an extracranial reference line, it devices (Nasiopoulos, 1992) for providing hori
obviates reliance on any intracranial reference zontal reference on the patient.
planes (Moorrees, 1985). In order to obtain a very good lateral cephalo
There are many ways of obtaining natural head metric imaging of the tongue, it has been recom
position. One method is defined by the subject's mended that the midline of the tongue should be
own feeling of a natural head balance - the self- coated with a radiopaque paste (Oesophagus paste)
balance position - and another method by the before exposure (Ingervall and Schmoker, 1990).
205
ASSESSMENT OF C R A N I O -
CERVICAL A N G U L A T I O N (10.1)
LANDMARKS A N D DEFINITIONS
cv2tg - tangent point of O P T on the odontoid
• ANS (sp) - spinal point - the apex of the anterior process of the second cervical vertebrae (Solow
nasal spine (Bjork, 1947); and Tallgren, 1971);
• ba - basion - the most posteroinferior point on gn - g n a t h i o n - the most inferior point on the
the anterior margin of the foramen m a g n u m mandibular symphysis (Bjork, 1947);
(Solow and Tallgren, 1976); N - nasion - the most anterior point of the fron-
• cv2ap - the apex of the odontoid process of the tonasal suture (Bjork, 1947);
second cervical vertebrae (Solow a n d Tallgren, 0 - opisthion - the most anteroinferior point of
1976); the posterior margin of the foramen magnum
• cv2ip - the most posterior and inferior point on (Solow and Tallgren, 1976);
the corpus of the second cervical vertebrae (Solow or - orbitale - the most inferior point of the orbit
and Tallgren, 1971); (Bjork, 1947);
• cv4ip - the most posterior and inferior point on p o - p o t i o n - the most superior point of the
the corpus of the fourth cervical vertebrae (Solow external auditory meatus (Bjork, 1947);
and Tallgren, 1971); Ptm (pm) - ptcrygomaxillary point - the inter
• cv6ip - the most posterior and inferior point on section between the nasal floor and the posterior
the corpus of the sixth cervical vertebrae contour of the maxilla (Bjork, 1947);
(Hellsing and Hagberg, 1990); S - sella - the centre of sella turcica (Bjork, 1947).
10.1 Cephalometric reference points and lines for assessing craniocervical angulation.
206
REFERENCE LINES
F CVT - the cervical vertebrae tangent - the pos • CVT-ML - the head position in relation to the
terior tangent t o the odontoid process through cervical column - angle between the cervical ver
cv4ip (Bjork, 1960); tebrae tangent (CVT) and the ML line (Solow
» EVT - the lower part of the cervical spine - the and Tallgren, 1971);
line through cv4ip and cv6ip (Hellsing and • CVT-NL - the head position in relation to the
Hagberg, 1990); cervical column - angle between the cervical ver
• FH - Frankfort horizontal - line connecting the tebrae tangent (CVT) and the NL line (Solow and
points porion (po) and orbitale (or); Tallgren, 1971);
• FML (FOR) - the foramen magnum line - line • CVT-NSL - the head position in relation to the
connecting basion (ba) and opisthion (o) (Solow cervical column - a n g l e between the cervical ver
and Tallgren, 1976; Huggare, 1991); tebrae tangent (CVT) and the NSL line (Solow
• HOR- true horizontal line - the line perpendic- and Tallgren, 1971);
I ular to VER (Solow and Tallgren, 1971); • CVT-RL - the head position in relation to the
!• ML - mandibular line - tangent line to the lower cervical column - angle between the cervical ver
border of the mandible (on point go) through tebrae tangent (CVT) and the RL line (Solow and
gnathion(gn) (Bjork, 1947); Tallgren, 1971);
I NL - nasal line - line connecting the anterior • OPT-CVT - the inclination of the two cervical
nasal spine (ans or sp) and pterygomaxillare reference lines to each other, i.e. the cervical cur
I (Ptm) (Bjork, 1947); vature - angle between the odontoid process
1
NSL - the anterior cranial base - line connect tangent (OPT) and the cervical vertebrae tangent
ing the centre of sella turcica (s) and nasion (n) (CVT) (Solow and Tallgren, 1971);
(Bjork, 1947); • OPT-FH - the inclination of the cervical column
• OPT- the odontoid process tangent. The poste in relation to the Frankfort horizontal line-angle
rior tangent to the odontoid process through between the odontoid process tangent (OPT) and
j cv2ip (Solow and Tallgren 1971); the FH line (Solow et al, 1993);
v RL - the ramus plane - tangent line on the pos • OPT-FML - angle between the odontoid process
terior contour of ramus ascentens (Bjork, 1947); tangent (OPT) and the foramen magnum line
|" VER - true vertical line - the vertical line pro (FML) (Solow and Tallgren, 1976);
jected on the film (Solow and Tallgren, 1976). • O P T - H O R - the inclination of cervical column
to the true horizontal - angle between the
odontoid process tangent (OPT) and the hori
VARIABLES zontal line (HOR) (Solow and Tallgren, 1971);
• OPT-ML - the head position in relation to the
• cv2ap-cv4ip - the length of the cervical column cervical column - angle between the odontoid
- linear distance between the point cv2ap and process tangent (OPT) and the ML line (Solow
cv4ip (Solow and Tallgren, 1976); and Tallgren, 1971);
• CVT-EVT - the cervical lordosis - angle between • O P T - N L - the head position in relation to the
the cervical vertebrae tangent (CVT) and the EVT cervical column - angle between the odontoid
line (Hellsing and Hagberg, 1990); process tangent (OPT) and the NL line (Solow
i CVT-FH — the inclination of the cervical column and Tallgren, 1971);
in relation to the Frankfort horizontal line - angle • OPT-NSL - the head position in relation to the
between the cervical vertebrae tangent (CVT) and cervical column - angle between the odontoid
i the FH line (Solow et al, 1993); process tangent (OPT) and the NSL line (Solow
CVT-FML- angle between the cervical vertebrae and Tallgren, 1971);
tangent (CVT) and the foramen magnum line • OPT-RL - the head position in relation to the
I F M L ) (Solow and Tallgren, 1976); cervical column — angle between the odontoid
CVT-HOR - the inclination of cervical column process tangent (OPT) and the RL line (Solow
■to the true horizontal - angle between the cervical and Tallgren, 1971).
vertebrae tangent (CVT) and the horizontal line
(HOR) (Solow and Tallgren, 1971);
207
ASSESSMENT OF PHARYNGEAL
RELATIONSHIPS (10.2)
LANDMARKS AND DEFINITIONS
AA - the most anterior point on the atlas verte at2 - the intersection point between a line from
brae (Bibby and Preston, 1981); the pterygomaxillary point (Ptm) to the midpoint
ANS (sp) - spinal point - the apex of the anterior of a line joining basion (Ba) and the centre of sella
nasal spine (Bjork,1947); turcica (S), and the anterior contour of the
Ap - point on the posterior wall of nasopharynx adenoid soft tissue shadow (Linder-Aronson,
(Frickeetal, 1993); 1970);
apw2 - the anterior pharyngeal wall along the at3 - the intersection point between a line from
line intersecting cv2ia and hy (Athanasiou et al, the pterygomaxillary point (Ptm) to basion (Ba)
1991); and the anterior contour of the adenoid soft
apw4 - the anterior pharyngeal wall along the tissue shadow (Linder-Aronson, 1970);
line intersecting cv4ia and hy (Athanasiou et al, atpl - the intersection point between a line from
1991); the pterygomaxillary point (Ptm) to the midpoint
atl - the most anterior part of the adenoid mass of a line joining basion (Ba) and the centre of sella
(Hibbert and Whitehouse, 1978); turcica (S), and the posterior contour of the
adenoid soft tissue shadow (Linder-Aronson,
1970);
VER
HOR
10.2 Cephalometric reference points and lines for assessing pharyngeal relationships.
208
Cephalotnefric Assessment
• Ba - basion - the most posteroinferior point on • Ptm (pm) - pterygomaxillary point - the inter
the anterior margin of the foramen magnum section between the nasal floor and the posterior
(Solow and Tallgren, 1976); contour of the maxilla (Bjork, 1947); defined as
• cv2ia - the most anteroinferior point on the Cp by Fricke et ai, 1993;
I corpus of the second cervical vertebrae

(Athanasiou et al, 1991);
• cv4ia - the most anteroinferior point on the
• S - sel la - the centre of sella turcica (Bjork, 1947);
• SPW - the intersection point between a perpen
dicular line to the palatal plane at Ptm and the
corpus of the fourth cervical vertebrae superior wall of the nasopharynx (Mazaheri et al,
(Athanasiou et al, 1991); 1977);
• E - the most inferior and anterior point of the • tb - the intersection point of a line from point B
epiglottis (Lowe et al, 1986); through go and the base of the tongue (Riley et
[• Gp (at4) - posterior wall of nasopharynx (Fricke al, 1983);
et al, 1993) - point on the adenoid tissue • UPW (PPW) - the upper pharyngeal wall - the
(Sorensen et al, 1980); point on the posterior pharyngeal wall identified
• Hp - the anterior wall of nasopharynx (Fricke by an extension of the palatal plane (ANS-PNS)
et al, 1993) - point on the upper surface of the (Lowe et al, 1986); defined as PPW by Mazaheri
palatine velum (Sorensen et al, 1980); etal, 1977.
• hy - the most superior and anterior point on the
body hyoid bone (Athanasiou et al, 1991);
• Ip - point on the posterior wall of nasopharynx VARIABLES
(Fricke et al, 1993);
• Kp(U)-the tip of the uvula (Fricke etal, 1993); • AA-PNS - linear distance between the most
• Lp - point on the anterior wall of oropharynx anterior point on the atlas vertebrae and the tip
(Fricke etal, 1993); of the posterior nasal spine (Bibby and Preston,
• LPW - the lower pharyngeal wall (LPW) - the 1981);
point on the posterior pharyngeal wall identified • AA-PNS + PAS - posterior airway space (Lowe
by an extension of a line through E drawn etal, 1986);
parallel to the SN plane (Lowe et al, 1986); • Ap-Cp (Ap-Ptm) - the greatest distance between
•ma - point on the posterior wall of the maxillary the pterygomaxillary point (Cp or Ptm) and the
antrum (Hibbert and Whitehouse, 1978); posterior wall of nasopharynx (Ap) (Fricke et al,
• Mp - point on the posterior wall of oropharynx 1993);
(Fricke etal, 1993); • apw2-ppw2 - the pharyngeal depth - linear
• MPW - the middle pharyngeal wall - the point distance on the line connecting the point hy and
on the posterior pharyngeal wall identified by an the point cv2ia, between the intersection point on
extension of a line between the midpoint of the the anterior and on the posterior pharyngeal
occlusal surface of the mandibular molar and the walls (apw2 and ppw2, respectively) (Athanasiou
mandibular incisor tip (Lowe et al, 1986); etal, 1991);
• N - nasion - the most anterior point of the fron- • apw4-ppw4 - the pharyngeal depth - linear
tonasal suture (Bjork, 1947); distance on the line connecting the point hy and
• PNS - the tip of the posterior nasal spine - the the point cv4ia, between the intersection point on
most posterior point at the sagittal plane on the the anterior and on the posterior pharyngeal
bony hard palate (Bibby and Preston, 1981); walls (apw4 and ppw4, respectively) (Athanasiou
• ppw2 - the posterior pharyngeal wall along the etal, 1991);
line intersecting cv2ia and hy (Athanasiou et al, • Ba-PNS - dimension of the bony pharynx -
1991); linear distance between point Ba and PNS (Bacon
j ppw4 - the posterior pharyngeal wall along the etal, 1990);
line intersecting cv4ia and hy (Athanasiou et al, • Jp-Kp - the smallest distance between the end of
1991); the velum (Kp or U) and the posterior wall of
> ppwb - the intersection point of a line from B nasopharynx (Ip) (Fricke et al, 1993);
through go and the base of the posterior pha • Mp-Lp - the smallest distance between the
ryngeal wall (Riley et al, 1983); anterior wall (Lp) and the posterior wall (Mp) of
oropharynx (Fricke et al, 1993);
209
• N-S-Ptm - the shape of the bony nasopharyngeal wall (ppwb), both determined by an extension of
space - angle between the lines N-S and S-Ptm a line from point B through go (Riley et al, 1983);
(Solow and Tallgren, 1976); • Ptm-PPW - the depth of nasopharynx - linear
• P I - the shortest distance from the most anterior distance between the pterygomaxillary point
part of the adenoid mass (atl) to the posterior (Ptm) or the point PNS and the intersection point
wall of the maxillary anthrum (ma) (Hibbert and between the palatal plane and the posterior wall
Whitehouse, 1978; Lowe et al, 1986); of the nasopharynx (PPW) (Mazaheri et al,
• P2 - the distance of the ptcrygomaxillary point 1977);
(Ptm) to the adenoid tissue (at2) along the line • Ptm-SWP - the height of nasopharynx - linear
from the pterygomaxillary point to the midpoint distance between the pterygomaxillary point
of a line joining basion (Ba) and the centre of sella (Ptm) and the intersection point between a per
turcica (S) (Linder-Aronson and Henrikson, pendicular line to the palatal plane at Ptm and the
1973; Lowe etal, 1986); superior wall of the nasopharynx (SPW)
• P3 - the distance from the pterygomaxillary point (Mazaheri et al, 1977);
(Ptm) to the posterior pharyngeal wall (at3) along • Ptm-S-Ba - the shape of the bony nasopharyn
the line from the pterygomaxillary point to geal space - angle between the lines Ptm-S and
basion (Ba) (Linder-Aronson and Henrikson, S-Ba (Solow and Tallgren, 1976);
1973; Lowe etal, 1986); • T1 - the soft tissue shadow (atl-atpl) on a line
• P4 (Gp-Hp) - the shortest distance from the from the pterygomaxillary point (Ptm) to the
upper surface of the palatine velum to the midpoint of a line joining basion (Ba) and the
adenoid tissue (at4) (Sorensen et al, 1980; Lowe centre of sella turcica (S) (Linder-Aronson, 1970);
et al, 1986). Also defined as the smallest soft • T2 - the soft tissue shadow (at2-Ba) on a line
tissue distance between the posterior (Gp) and from the pterygomaxillary point (Ptm) to basion
anterior wall (Hp) of nasopharynx (Fricke et al, (Ba) (Linder-Aronson, 1970);
1993); • UPWx + MPWx + LPWx - anteroposterior
• PAS - posterior airway space - linear distance position of posterior pharyngeal wall (the x co
between a point on the base of the tongue (tb) ordinates of TJPW, iMPW and LPW) (Lowe et al,
and another point on the posterior pharyngeal 1986).
210
Cepbalometric Assessment
ASSESSMENT OF SOFT PALATE

DIMENSIONS (10.3)
• ISP - point on the oral contour of velum - the U (Kp) - the tip of the uvula (Mazaheri et al,
most prominent point on the inferior soft palate 1977); defined as Kp in Fricke et al, 1993);
surface (Mazaheri et al, 1994);
• PNS - the tip of the posterior nasal spine - the
most posterior point at the sagittal plane on the VARIABLES
bony hard palate (Mazaheri et al, 1977);
• Ptm (Pm) - pterygomaxillary point - the inter • U-Ptm (U-PNS, SP) - the length of the soft palate
section between the nasal floor and the posterior - linear distance between point U and PNS or
contour of the maxilla (Bjork, 1947); Ptm (Mazaheri et al, 1977; Bacon et al, 1990);
• SSP - point on the nasal contour of velum - the • SSP-ISP - velar thickness - the maximum dimen
most prominent point on the superior soft palate sion of the velum between its oral and nasal
surface (Mazaheri et al, 1994); surfaces (Mazaheri et al, 1994).
10.3 Cephalometric landmarks and variables for assessing soft palate dimensions.
211
ASSESSMENT OF H Y O I D BONE
P O S I T I O N (10.4)
ANS (sp) - spinal point - the apex of the anterior Ba - basion - the most posteroinferior point on
nasal spine (Bjork, 1947); the anterior margin of the foramen magnum
apw2 - the anterior pharyngeal wall along the (Solow and Tallgren, 1976);
line intersecting cv2ia and hy (Athanasiou et al, C3 - the most inferior anterior point on the third
1991); cervical vertebrae;
apw4 - the anterior pharyngeal wall along the cv2ia - the most anteroinferior point on the
line intersecting cv4ia and hy (Athanasiou et al, corpus of the second cervical vertebrae
1991); (Athanasiou et al, 1991);
ar - articulare - the intersection point between cv4ia - the most anteroinferior point on the
the external contour of cranial base and the corpus of the fourth cervical vertebrae
dorsal contour of the condylar head or neck (Athanasiou et al, 1991);
(Athanasiou et al, 1991); cv4ip - the most posterior and inferior point of
the fourth cervical vertebrae (Tallgren and Solow,
1987);
A^Sr^l^\s*
Po
NSL
■ w *-J ■—
/ \ ^T^ ^ -M
i ■ ir - '
*
f: u
r n
\
\
(
bv/^ A^^TRI 0 \
Ba7 Jrar \ /
NL ^r* \PNS -^"^ ^^v AMC S
1
^\hyaxis-NL ^ ^ ' X^HIMO ^r
J w a x i s - M l > > < ^ ' ^ CV2tgJT
■^hyaMs-B^N^\M L
VVA/ TIC ] ^ \ \ X )
cv2lA I 1 „ f\
cv4ip <!
/ jPPwSp^, >fj
Tm 1 /
Yj fapw4>affi hya ^ ^ \Gnposy /
gn^ /
i / | RL ^
CVT PolFH pTR1

FH
10.4 Cephalometric landmarks and lines for assessing hyoid bone position.
212
• cv2tg - tangent point of OPT on the odontoid • rls - the superior tangent point between the pos
process of the second cervical vertebrae (Tallgren terior contour of ramus ascentens and the tangent
and Solow, 1987); line on it (Solow and Tallgren, 1976);
• gn - gnathion - the most inferior point on the • S - sella - the centre of sella turcica; the centre of
mandibular symphysis (Bjork, 1947); the pituitary fossa of the sphenoid bone (Bjork,
• Gnpost - retrognathion - the most inferior pos 1947);
terior point on the mandibular symphysis (Bibby • tgo - gonion - the intersection point of mandibu
and Preston, 1981; Haralabakis et al, 1993); lar and ramus planes (ML and RL, respectively)
• go - the most posterior and inferior point of the (Solow and Tallgren, 1976).
mandible;
• H* - the intersection point between the perpen
dicular from H to the line connecting the point REFERENCE LINES
C3 and retrognathion (Bibby and Preston, 1981);
• hy (H) - the most superior and anterior point on • Ba-N - line connecting the points basion (Ba) and
the body of the hyoid bone (Tallgren and Solow, nasion (N);
1987); • C3-Gnpost - line connecting the most inferior
• hy' - hyoid prime - the perpendicular point from anterior point on the third cervical vertebrae (C3)
hy along the mandibular plane (Athanasiou et al, and the most inferior posterior point on the
1991); mandibular symphysis (retrognathion) (Bibby
• hya - the most anterior point of the hyoid and Preston, 1981);
(Haralabakis e t a l , 1993); • CVT - the cervical vertebrae tangent- the pos
• hyp - the most posterior point of the greater horn terior tangent to the odontoid process through
of the hyoid (Haralabakis et al, 1993); cv4ip (Bjork, 1960);
• is - the incisal tip of the most prominent maxil • FH - Frankfort horizontal plane;
lary incisor (Bjork, 1960). • ML (MP) - mandibular line (plane) - tangent line
• m - the most posterior point on the mandibular to the lower border of the mandible through
symphysis (Athanasiou et al, 1991); gnathion (gn) (Bjork, 1947);
• mc - the distobuccal cusp tip of the upper first • NL (PP) - nasal line (palatal plane) - line con
permanent molar (Bjork, 1960); necting the anterior nasal spine (ans or sp) and
• N - nasion - the most anterior point of the fron- pterygomaxillare (Ptm or pm) (Bjork, 1947);
tonasal suture (Bjork, 1947); • NSL (SN) - the anterior cranial base - line con
• Or - orbitale - the most inferior point of the necting the centre of sella turcica (s) and nasion
orbit; (n) (Bjork, 1947);
• PNS - the tip of the posterior nasal spine - the • OL (OP) - occlusal line (plane) - the line con
most posterior point at the sagittal plane on the necting the distobuccal cusp tip of the upper first
bony hard palate; permanent molar (mc) and the incisal tip of the
• Po - porion - the most superior point of the most prominent maxillary incisor (is) (Bjork,
external auditory meatus; 1960);
• PPW - the most posterior point of the pharyngeal • Poi-FH - vertical line drawn on Frankfort hori
wall along a parallel line on point hy to the zontal plane at porion (Po) (Haralabakis et al,
palatal plane (NL) (Haralabakis et al, 1993); 1993);
• PTR - the intersection point between the • PTRJ-FH - vertical line drawn on Frankfort hor
Frankfort horizontal line (FH) and the posterior izontal plane at the posterior border of pterygo
border of pterygomaxillary fissure (PTR) maxillary fissure (PTR) (Haralabakis et al, 1993);
(Haralabakis e t a l , 1993); • RL - the ramus line (plane) - tangent line on the
• rli - the inferior tangent point between the pos posterior contour of ramus ascentens (Bjork,
terior contour of ramus ascentens and the tangent 1947).
line on it (Solow and Tallgren, 1976);
213
Orthodontic Cephatometry
VARIABLES • hy-Gnpost - horizontal position of the hyoid -

linear distance between point hy and point
• C3-H - anteroposterior position of hyoid - linear Gnpost (Haralabakis et al, 1993);
distance between C3 and H (Bibby and Preston, •* hy—m - anteroposterior position of the hyoid -
1981); linear distance between point hy and point m on
• H - H ' - vertical position of the hyoid - linear the mandibular symphysis (Athanasiou et al,
distance between H and a perpendicular to the 1991);
C3-retrognathion line (Bibby and Preston, 1981); • hy-ML (hy-MP) - vertical position of hyoid -
• H-.MP + H-H 1 - vertical position of hyoid bone linear distance along a perpendicular from hy to
- the total amount of the distance H - M P and the mandibular plane (ML) on the intersection
H - H ' (Lowe e t a l , 1986); point hy3 (Solow and Tallgren, 1971);
• hy—apw2 — linear distance between point hy and • hy-NL (hy-PP) - vertical position of the hyoid
the anterior pharyngeal wall on point apw2 - linear distance along a perpendicular from hy
(Athanasiou et al, 1991); to the maxillarv plane (NL) (Solow and Tallgren,
• hy-apw4 - linear distance between point hy and 1976);
the anterior pharyngeal wall on point apw4 • hy-NSL (hy-SN) - vertical position of the hyoid
(Athanasiou et al, 1991); - linear distance along a perpendicular from hy
• hy axis - the long axis of the hyoid bone - line to the anterior cranial base (NSL) (Solow and
connecting the most anterior point of the hyoid Tallgren, 1976);
(hya) and the most posterior point of the greater • hy-OL (hy-OP) - vertical position of the hyoid -
horn of the hyoid (hyp) (Haralabakis et al, 1993); linear distance along a perpendicular from hy to
• hy axis-BaN - axial inclination of the hyoid bone the occlusal plane (Haralabakis et al, 1993);
- angular measurement between the long axis of • hy-Po_LFH - horizontal position of the hyoid -
the hyoid bone and the basion-nasion line linear distance along a perpendicular from hy to
(Haralabakis e t a l , 1993); the line P o l F H (Haralabakis et al, 1993);
• hyaxis—ML — axial inclination of the hyoid bone • hy-PPW - horizontal position of the hyoid -
- angular measurement between the long axis of linear distance between point hy and point PPW
the hyoid bone and the mandibular plane (Haralabakis et al, 1993);
(Haralabakis e t a l , 1993); • hy-PTRJ_FH - horizontal position of the hyoid -
• hyaxis-NL - axial inclination of the hyoid bone linear distance along a perpendicular from hy to
- angular measurement between the long axis of the line PTR1FH (Haralabakis et al, 1993);
the hyoid bone and palatal plane (Haralabakis et • hy-RL - anteroposterior position of the hyoid -
al, 1993); linear distance along a perpendicular from hy to
• hy-CVT - anteroposterior position of the hyoid the ramus plane (RL) (Ingervall and Schmoker,
- linear distance along a perpendicular from hy 1990);
to the cervical vertebrae tangent (CVT) (Solow • hy'-tgo - linear distance between point hy1 and
and Tallgren, 1976); point tgo (Athanasiou et al, 1991).
• hy-FH - vertical position of the hyoid - linear
distance along a perpendicular from hy to the
Frankfort horizontal line (Haralabakis et al,
1993);
214
ASSESSMENT OF T O N G U E
POSITION (10.5)
K
LANDMARKS
• ANS (sp) - spinal point - the apex of the anterior pt - the intersection point between the occlusal
nasal spine (Bjork, 1947); line (OL) and the contour of the tongue (Ingervall
• E - the most inferior and anterior point of the and Schmoker, 1990);
epiglottis (Lowe et al, 1986); Ptm (pm) - pterygomaxillary point - the inter
• ii - the incisal tip of the most prominent section between the nasal floor and the posterior
mandihuiar incisor (Solow and Tallgren, 1976); contour of the maxilla (Bjork, 1947);
• is - the incisal tip of the most prominent maxil pw - t h e intersection point between the occlusal
lary incisor (Bjork, 1960); line (OL) and the pharyngeal wall (Ingervall and
• Mc - point on cervical, distal third of the last per Schmoker, 1990);
manent erupted molar (Rakosi, 1982); TT - the tip of the tongue (Lowe et al, 1986);
• mc - the distobuccal cusp tip of the upper first U - the tip of the uvula or its projection on the
permanent molar (Bjork, 1960); Mc-ii line (Rakosi, 1979);
• 0 - the middle of the linear distance U-ii on the ut - point on the dorsum of the tongue - the
Mc-ii line (Rakosi, 1982); nearest point on the contour of the tongue to the
maxillary plane (Ingervall and Schmoker, 1990).
10.5 Cephalometric landmarks and lines for assessing the position of the tongue.
215
REFERENCE LINES • tg5 - partial length of the tongue - linear distance

between point 0 and the intersection point of the
• Ltgl - line through point 0 and ii (Rakosi, 1982); Ltg5 line with the contour of the tongue (Rakosi,
• Ltg2 - line constructed on point 0 of the Mc-ii 1982);
line, producing an angle of 30° with the Mc-ii • tg6 - partial length of the tongue - linear distance
line (Rakosi, 1982); between point 0 and the intersection point of the
• Ltg3 - line constructed on point 0 of the Mc-ii Ltg6 line with the contour of the tongue (Rakosi,
line, producing an angle of 60° with the Mc-ii 1982);
line (Rakosi, 1982); • tg7 - partial length of the tongue - linear distance
• Ltg4 - the perpendicular bisection line on point between point 0 and the intersection point of the
0 to the Mc-ii line (Rakosi, 1982); Ltg7 line with the contour of the tongue (Rakosi,
• Ltg5 - line constructed on point 0 of the Mc-ii 1982);
line, producing an angle of 120° with the Mc-ii • TGH - tongue height - linear distance along the
line (Rakosi, 1982); perpendicular bisector of the E-TT line to the
• Ltg6 - line constructed on point 0 of the Mc-ii tongue dorsum (Lowe et al, 1986);
line, producing an angle of 150° with the Mc-ii • TGL - tongue length - linear distance between
line (Rakosi, 1982); E and TT (Lowe et al, 1986);
• Ltg7- line through point 0 and U (Rakosi, 1982); • ut-NL - the shortest distance between the dorsum
• Mc-ii - line through the points Mc and ii of the tongue (from the point ut) and the maxil
(Rakosi, 1982); lary plane (NL) (lngervall and Schmoker, 1990);
• NL - nasal line - line connecting the anterior
nasal spine (ans or sp) and pterygomaxillare
(Ptm) (Bjork, 1947); NORMS O N CEPHALOMETRIC
• OL - occlusal line - the line connecting the dis- ASSESSMENT OF HEAD POSTURE
tobuccal cusp tip of the upper first permanent
molar (mc) and the incisal tip of the most promi Norms on cephalometric assessment of head posture
nent maxillary incisor (is) (Bjork, 1960). have been provided by the following groups of
healthy subjects.
1. Sample of Solow and Tallgren (1971) - Danish
VARIABLES male dental students: lateral cephalograms were
taken while the subjects were standing with the
• pt-pw - the distance of the tongue from the pha- head in the natural head position (mirror
ryngeal wall - linear distance between a point on position). Sample size: 120; age range: 20-30
the contour of the tongue (pt) and a point on the years.
pharyngeal wall (pw) measured on the occlusal 2. Sample of Huggare (1986) -Finnish male dental
line (OL) (lngervall and Schmoker, 1990); students: lateral cephalograms were taken while
• tgl - partial length of the tongue - linear distance the subjects were standing with the head in the
between point 0 and the intersection point of the natural head position (external reference:
Ltgl line with the contour of the tongue (Rakosi, horizon). Sample size: 50; age range: 19-30 years.
1982); 3. Sample of Tallgren and Solow (1987) -Young
• tg2 - partial length of the tongue - linear distance Finnish women: lateral cephalograms were taken
between point 0 and the intersection point of the while the subjects were sitting with the head in
Ltg2 line with the contour of the tongue (Rakosi, the natural head position (no external reference)
1982); (Tallgren 1957). Sample size: 81; age range:
• tg3 - partial length of the tongue - linear distance 20-29 years.
between point 0 and the intersection point of the 4. Sample of Tallgren and Solow (1987): Middle-
Ltg3 line with the contour of the tongue (Rakosi, aged Finnish women. Sample size: 64; age range:
1982); 30-49 years.
• tg4 - partial length of the tongue - linear distance 5. Sample of Tallgren and Solow (1987): Elderly
between point 0 and the intersection point of the Finnish women. Sample size: 46; age range:
Ltg4 line with the contour of the tongue (Rakosi, 50-81 years.
1982);
216
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220
CHAPTER 11
Aspects of Digital Computed Radiography with

Cephalometric Applications
Alberto Barenghi, Evangelista G Mancini and Antonino Salvato
INTRODUCTION THE DIGITAL COMPUTED

RADIOGRAPHY SYSTEM (CR)
Diagnostic radiology still largely relies on conven
tional imaging, because analogic radiography In the space of only one hundredth of a second, a
contains much more information than can be punctiform X-ray beam stimulates a two-dimen
obtained using a digital radiology system (Johnson sional memory sensor. This memorized data is first
and Abenathy, 1983). converted into an electrical signal and then into a
Conventional radiography requires at least 4-6 two-dimensional numerical image consisting of
megabytes to obtain a high quality image, whereas pixels (dots of various shades of grey whose posi
computerized tomography (CT) requires 0.5 tions are defined by means of x and y co-ordinates).
megabytes, magnetic resonance imaging (MR1) This image can then be enhanced by simultane
requires 0.3 megabytes, and ultrasound (US) ously multiplying the value of each pixel (a dot-by-
requires only 0.07 megabytes. Computed radiog dot operation affecting the contrast) and modifying
raphy (CR) systems have overcome the technologi the relationships between the values of the pixels
cal difficulties of reducing or eliminating the making up a certain area (a two-dimensional oper
differences in the information that can be obtained ation affecting spatial frequency).
from conventional and digital radiographs without The enhancement brought about by these adjust
overturning the criteria used in their evaluation. ments to the content of the pixels makes it possible
A CR system can: to vary the type of response that can be obtained
I surpass conventional analogic radiology; from the detector in relation to the dose.
• reduce radiation dose exposure to a minimum; Conventional radiographic systems can only provide
• convert the diagnostic information of an analogic a fixed response determined by the film-screen
X-ray ro digital signals and enhance information system.
from underexposed two-dimensional X-rays; Furthermore, the optimum contrast for each CR
• provide more sensitive, higher-definition, and image can be individually selected (Salvini, 1988;
diagnostically more meaningful images than Paini et al, 1991; Carattini et al, 1992). With the use
those provided by conventional radiology, and in of various X-ray generation systems and the exis
real time; tence of different types of sensors for converting
' process images in such a way as to enable the analogic into digital signals, a large number of CR
establishment of a database; systems are commercially available.
• improve the reliability and diagnostic accuracy of In this chapter, a direct acquisition system is
digital technologies (Tateno et al, 1987). described, which is based entirely on a totally digital
technology first proposed by Japanese researchers
in 1983 (Sonoda et al, 1983). The sysrem consists
of a series of functionally independent subunits that
make radiographic film and a telecamera unneces
sary (Tateno et al, 1987) (11.1).
221
TECHNICAL ASPECTS plate is capable of temporarily storing X-ray energy

in its light-sensitive phosphor crystals. Then, when
Imaging plate (IP) a scanning He-Ne laser beam hits the crystals, the
The imaging plate is a sensor capable of receiving stored X-ray energy is emitted in the form of blue
and recording the information relating to an X-ray light. This optical signal is then converted into an
image. It is a substitute for the conventional film- electrical signal, which is read by the image reader
screen system (11.2). The imaging plate is made up (IRD). The luminescence of the optical signal
of different layers. When stimulated, the imaging depends on the wavelength of the light irradiated
CR Image
V
Controller Automatic film

computer processor
X-ray tube Patient

7T
R
Image reader (IRD) Image processor (IPC) Image recorder (IRC)
(Converting X-ray (Gradation processing, (Converting electric
image to electric frequency processing, signals to light for
signals) etc.) film recording)
^J
/ Imaging plate (IP)
n
Data recorder
(MT MD. Film
optical display)
31
High resolution
CRT display
I I. I General diagram of the computed radiography system. (From Tateno et al, 1987; used with permission.)
222
Digital Computed Radiography
nto the imaging plate; this luminescence is completely the processing of the image, and to obtain
xpressed in terms of the photostimulation spec- stable digital radiographs under all X-ray conditions.
urn. The amount of blue light emitted by the The dissolve is due to the fact that the image gen
imaging plate is linearly dependent on the X-ray erated by the X-rays and stored on the imaging plate
dose, with a range of more than 1/104 (11.3). fades with time and with any increase in temperature.
This wide dynamic range makes it possible to The quality of the images obtained by the imag
detect precisely the small differences in the X-ray ing plate can be expressed in terms of sensitivity,
absorption of each tissue in the organism, to automate granulosity, and sharpness.
Protective layer
Phosphor layer
BaFBr: Eu2 crystal
Support
Backing layer
Bar Code label
11.2 Structure of the imaging plate. (From Tateno et al, 1987; used with permission.)
11.3 Dynamic range of the imaging plate.

(From Tateno et al, 1987; used with per
* mission.)
•
5 •
1 10 -
10 4 -
£
ri
si 10'-
Q-
10'-
10°
1o* 10- 10° 10' 102 10 3
Exposure (mR)
223
Image reading (IRD) The quality of the image that can be obtained by
An image generated by X-rays and stored on an the image reader depends on a number of facrors
imaging plate is spatially continuous analogic infor (11.5):
mation. In order to decode the information and • the sharpness of the photographic image;
convert it into a digital signal, a laser scanner is • the frequency of the optical or electrical response;
used. The converted electrical signals are analogic • the photographic granulosity; and
signals that arc proportional to the amount of pho- • the electrical or optical noise.
tostimulated light emitted. These signals are ampli The imaging plate transits between the imaging unit
fied and logarithmically converted before being and the CR reading unit, while the information
transmitted through an analogic-digital converter, decoded by the latter is converted into digital
which changes them into digital signals (11.4). signals, which - together with the patient's personal
I 1.4 Diagram of the image reading sys

tem. (From Tateno et al, 1987; used with
permission.)
OPTICAL SCANNER
PHOTOMULTIPLIER TUBE
LIGHT G U I D E
i
ANALOG
T O DIGITAL
AMPLIFIER
CONVERTER
II II ii i I i in
MOTOR IIOIIOOIIOOIOOIOIOIII
Latent Analog Digital

X-ray image electrical image
quanta (on IP) Light signal data
Imaging plate Imaging plate Photo-electnC conversion

Quantization
Recording Laser beam scanning and Signal processing
(Imaging plate) (Reader optical system) (Reader electrical system)
Image
Sharpness ( Sharpness
of imaging plate J
A
V
f Response in spatial
frequency domain
1 H Response in
electrical frequency
domain
c Transfer
characteristic )
qualify
Mottle No-
uniformity
Artifacts (
Quantum noise
) (
Optical noise/non-uniformity
) (
Electrical noise ) [
V
Quantization
noise
^
J
C IP structure ^ i
mottle, granularity J
<•
Quantization artifacts
•>
I 1.5 Factors determining image quality in CR reading system. (From Tateno et al, 1987; used with permission.)
224
data and imaging details from the input section - Image recording ( I R C )
is then sent to the electronic image processing A correct radiographic diagnosis requires high-
section, where the CR image is processed and quality images. In the case of a CR system, a hard
printed on photographic film. The image reader is copy on film should be made. The most effective
capable of processing films with formats of 45 cm method for doing this is to record the signals coming
x 35 cm, 35 cm x 35 cm, 25 cm x 30 cm, and 20 cm from the image directly onto the film by means of
x25 cm (Table 11.1). a laser printer. This method is free from any optical
At the level of the image reader, the imaging plate distortion and allows high-quality images to be
accumulator has a storage capacity of more than 60 obtained with the amount of recorded light being
plates, a sampling rate of 5-10 pixels/mm, a level of directly controlled by digital signals.
grey of 10 bits (A/D), and a laser field diameter of A high-definition laser printer or image recorder
10 microns. has a structure similar to that of the laser scanner
used to detect the information stored on the image
Image processing ( I P C ) plate. The image recorder is capable of bidimen-
The image is processed by the image processor in sionally and sequentially scanning the whole surface
such a way that the display shows an image that can of the film by means of the emission of a flashing
be used for diagnostic purposes. The characteristics He-Ne laser beam that is specific to the CR system
of the display (gradation, frequency, and subtrac and dependent on the sensitivity of the film. The
tion) are controlled automatically. To optimize spatial resolution of a laser printer is 10 pixels/mm
control over the characteristics of the display, adjust and the diameter of the laser beam is 80 microns.
ments of gradation, frequency, and image can be Furthermore, the CR system allows any type of
made to allow low radiographic contrast levels to image enlargement or reduction to be obtained. The
be reached. laser printer prevents any false edges resulting from
Reading Recording
spatial spatial Image
IP size resolution resolution size Recording
(cm) (pixels/mm) (pixels/mm) reduction format
Table I I. I Image size and format (From Tateno et al, 1987.)
225
resolution defects, even if the gradation has been CEPHALOMETRIC APPLICATIONS

modified during the digital processing preceding the
recording on film. When the image is produced by The digital computed radiology (CR) system has
a 45 cm x 35 cm, 35 cm x 35 cm, or 25 cm x 30 only recently been used during routine orthodon
cm image plate, it is reduced when it is recorded on tic evaluations. Some recent studies have investi
film. The laser printer uses CR 633 film, which has gated the differences of radiogenic exposure dose
a spectral sensitivity of about 633 nm (the wave between conventional cephalometric radiography
length of an He-Ne laser). The laser printer is and the CR system (Barenghi, 1992; Mancini ctal,
directly connected to an automatic developer 1992; Barenghi et al, 1993a). These studies were
(Sonodaetal, 1983). performed both on a dry skull and on a group of 70
I 1.6 Lateral cephalogram negative. I 1.7 Lateral cephalogram positive.
I 1.8 Posteroanterior cephalogram negative.
226
patients with dentofacial anomalies. The ortho in the posteroranterior projections to 40-50% in the
dontic evaluations were made according to well- lateral projections (Barenghi, 1992; Barenghi et al,
defined criteria (Gianni, 1980; Langlade, 1978, 1993b).
1983; Rakosi and Jonas, 1992) by means of lateral In orthodontic patients, the absorbed radiogenic
and posteroanterior cephalometric projections dose during conventional radiology exposure was
(11.6-11.8). The X-ray machine used was a Fiad reported to be 48 mRem and 70 mRem for the
Rotograph 230/EUR and the CR system was a lateral and posteroanterior projections respectively.
Toshiba TCR-201 (Toshiba, 1991). In order to However, the CR system allowed a reduction in the
obtain images of a pre-established density, the radiogenic dose absorbed by the patients to the
Toshiba TCR-201 was equipped with an automat levels of 28.6% and 58.4% respectively.
ic sensitivity-latitude reading mechanism located in
the image reader. The algorithm underlying this
mechanism is known as the exposure data recog TECHNICAL TRENDS
nizer (EDR) (Tateno et al, 1987).
Furthermore, the CR system allowed both The future of CR systems can be seen in terms of
negative and positive radiographic images to be their specific characteristics, bearing in mind that
processed. The positive image adopted for the lateral they need to be used in a routine manner. The three
projection radiography of the skull was particular most important characteristics of the CR system
ly useful for highlighting profile soft tissues. (Tateno etal, 1987) are:
Moreover, the Toshiba display allowed enlarged • the digital imaging;
images of specific anatomical structures within each • the wide latitude; and
cephalometric projection. The parameters usually • the reduced radiogenic exposure dose.
adopted in conventional radiography (Gianni, 1980;
Rossetti, 1987) were used to choose the preliminary The continuous improvements in digital image pro
radiogenic exposure dose during CR system both on cessing are due to developments in the field of elec
skull and on patients. The radiogenic exposure dose tronics, particularly the construction of miniature
of the two methods was calculated as the absorbed semiconductors and increasingly sophisticated
dose at skin level; it was expressed in millirems. hardware and software systems. A further aspect is
Optimum exposure values have been obtained the type of technology used for saving inventoried
during the course of dry skull examinations by pro spaces and, therefore, the construction of databas
gressively or alternatively reducing the kilovoltage es (Table 11.3).
|and the radiogenic exposure time to levels that are Erasable optical discs are currently the most
still capable of providing sharp images of the struc advanced form of memory storage, but it will
tures whose landmarks constitute the cardinal probably be possible to make a five- to tenfold
elements of cephalometric analyses (Table 11.2). reduction in memory space in a few years' time. The
When the skull was evaluated, the lowest radi simplest way of compressing data is to create a
ogenic doses in conventional radiography that were smaller number of larger elements. However, this
able to provide clear and detailed lateral and pos leads to a worsening in the quality of the image and,
teroanterior cephalograms were 40 mRem and 75 therefore, to greater diagnostic difficulties.
mRem respectively. In the same projections using the Currently, electronic archiving requires only one
CR system, the best radiogenic dose was 20 mRem twentieth to one hundredth the space necessary for
and 50 mRem respectively. Thus, on the dry skull, archiving film.
the use of the CR system allowed a reduction in the
absorbed radiogenic dose from a minimum of 34%
227
to
a b l e I 1.2 Results o f an investigation f o r c o m p a r i n g cephnJometric e x p o s u r e s of c o n v e n t i o n a l radiology a n d digital c o m p u t e d radiology. (BarenRhi. 1992.)

CONCLUSION
The advantages of digital computed radiology can Management
be summarized under the following headings The correct identification of patients via computer
(Barenghi et al, 1993b): terminals, the establishment of databases, the pos
sibility of remote image transmission, and the inter
biology connection of all types of digital radiological
IThe enormous reduction in the X-ray dose absorbed equipments allow a more organic and rapid man
by the skin at each orthodontic examination leads agement of routine diagnostic and community
to a reduction in the radiation risk to the patient. services.
Diagnosis Economics
CR systems provide high-quality images that have The possibility of installing a digital system without
undoubted advantages in terms of the amount and making any substantial changes in existing radio
quality of the information they contain. Further logical technology, as well as the savings in film
more, they make possible the optimization of the costs deriving from the optimization of each radi
processing of the images in terms of contrast, gra ograph, offer appreciable economic advantages. The
dation, sharpness, and granulosity, thus allowing the only disadvantage is the high cost of the system, the
gathering of information that is of greater diagnos need for a space of at least 50 square metres for its
tic significance. installation, and the need for specialized training of
the operating staff.
Storage method
Optical disc storage Film storage
Storage form Optical disc cartridge Film jacket

(20 mm thick) (20 films/jacket = 8 mm thick)
Storage capacity
Reversible compression 242,000 images/m3 2,000 images/m:
(compression to halj (20 times file storage)
Irreversible compression 1,200,000 images/m3

(compression to lltO) 00 times file storage)
Table I 1.3 Comparative table of image archiving systems. (Tateno et al, 1987.]
229
REFERENCES
Barenghi A (1992) Applicazione della radiologia Langlade M (1983) Diagnosi ortodontica. (Scienza
digitate nel check-up ortognatodontico. Test di spe- e Tecnica Dentistica Edizioni Internazionali: Milan.)
cializzazione in Ortognatodonzia. (Universita degli
Studi di Milano: Milan.) Mancini EG, Barenghi A, Dal Maschio A, Salvato
A (1992) Use of digital radiology in orthodontic
Barenghi A, Mancini EG, Perrotti G, Salvato A roentgencephalography. Lido-Venice: Proceedings
(1993a) Applicazione della radiologia digitale nel of the 68th Congress of the European Orthodontic
check-up ortognatodontico (Nota I). Ortognato Society.
donzia Italiana 2:271-83.
Paini L, Oliva A, Salvato A (1991) Radiografia
Barenghi A, Mancini EG, Rusca M, Salvato A digitale e tradizionale a confronto nella diagnostica
(1993b) Applicazione della radiologia digitale nel per imaging odontoiatrica. UIO e RAM X: 11-18.
check-up ortognatodontico (Nota II). Ortognato
donzia Italiana 2:481-7. Rakosi T, Jonas I (1992) Diagnostica ortognato-
dontica. ( Masson: Milan.)
Garattini G, Nessi R, Blanc M, Pignanelli C (1992)
Introduzione di metodiche radiografiche innovative Rossetti G (1987) Radiologia odontoiatrica.
in ortodonzia: la radiologia digitale. Ortognato (Edizioni Libreria Cortina: Vernona) 297-300.
donzia Italiana 1:635-8.
Salvini E (1988) Radiografia digitale con detettori
Gianni E (1980) La nuova ortognatodonzia. (Piccin: fotoemittenti. Radiol Medica 76:545-51.
Padua.)
Sonoda M, Takano M, Miyahara J, Kato H (1983)
Johnson JL, Abenathy DL (1983) Radiology Radiology 148:833-8.
146:851-3.
Tateno Y, linuma T, Takano M (1987) Computed
Langlade M (1978) Cefalometria ortodontica. Radiography. (Springer: Berlin.)
(Scienza e Tecnica Dentistica Edizioni Inter-
nazionali: Milan.) Toshiba (1991). Application Manual (Routine
Processing) for Toshiba Computed Radiography
Model TCR-20L (Toshiba Corporation, no. 2B451-
005E.)
230
CHAPTER 12
Computerized Cephalometric Systems

Athanasios E Athanasiou and Jens Kragskov
INTRODUCTION al,1989) because it is only necessary to digitize the

radiological points directly on the cephalogram or
Nowadays, orthodontic offices use computers for the tracing paper, and the calculations are then done
many purposes, including appointments, recalls, within seconds (Kess, 1989). This process removes
appointment cards, patient tracking, correspon human error except for errors of landmark identi
dence, insurance filing and billing, accounting, fication (Isaacson et al, 1991).
cephalometrics, model analysis, diagnostic video In addition to the speed advantage, computerized
imaging, treatment records, daily work sheets, cephalometry facilitates the use of double digitiza
I inventory, supply orders, form generation, labora tion of the landmarks and thus significantly increas
tory sequencing, and database of information for es the reliability of the analysis (Baumrind and
surveys concerning the performance of the office Frantz, 1971; Erikscn and Bjorn-Jorgensen, 1988).
(Keimetal, 1992). If double digitization and calculation of the mean-
In addition to these functions, academic ortho points is performed, the chance that none of these
dontic institutions use computers for research data points are more than two standard deviations away
collection and elaboration, teaching purposes, and from the real point approximates 98%, leaving only
audiovisual material preparation (Pedersen et al, 2% chance for errors bigger than two standard devi
1988). ations (Baumrind, 1980; Erikscn and Bjorn-
Computerized cephalometric systems are used in Jorgensen, 1988). Although clinicians tend to think
orthodontics for diagnostic, prognostic, and treat that double digitization is of importance only to
ment evaluation, and their popularity has increased research applications, it should be remembered that
steadily since their introduction to the market in this procedure significantly decreases errors of the
thel970s. It has been suggested that in North cephalometric analysis during the planning of an
America about 10-15% of orthodontists now use individual patient's diagnosis and treatment.
computers for diagnosis, and it is expected to be a In addition to the great advantages of comput
growth rate of 10% a year in this market (Keim et erized cephalometric research applications, which
al, 1992). are described in Chapter 9, there are several other
benefits of this method. These include:
• easy storage and retrieval of cephalometric values
WHY USE COMPUTERIZED and tracings;
CEPHALOMETRY? • integration of the cephalometric registrations
within an office-management computerized
Before computerized cephalometry was employed, system; and
all angular and linear measurements were calculat • combination of the cephalometric data with
ed manually after tracing the bone and soft tissues patients' files, photographs, and dental casts
and identifying the landmarks related to the specific (Isaacson et al, 1991).
analysis used (Broadbent, 1931; Hofrath, 1931;
Downs, 1952). Cephalometric prediction of growth and the
The manual technique is time consuming, outcome of orthodontic treatment by means of com
whereas computerized cephalometry is very fast (Liu puters presents the same limitations as the various
and Gravely, 1991; Jacobson 1990; Davis and manual methods (Baumrind, 1991). On the other
Mackay, 1991). It can be performed in 10% of the hand, in orthognathic surgery patients, the possi
time of a normal manual registration (Harzer et bilities for computerized cephalometric prediction
231
of the surgical outcome on hard tissue and soft is recorded directly and converted to a digital image,
tissue profile are better than those of growth pre has facilitated the direct use of a mouse on the
diction or the prediction of the outcome of ortho screen (Isaacson et al, 1991). Before this , lateral and
dontic treatment (Donatsky et al, 1992; Grub, frontal cephalograms were digitized using a video
1992). However, this prediction only reflects the or an image-capture expansion board attached to
surgeon's ability to perform the planned surgery and the computer. However, this method has shown lim
the ability of the dentist to perform the cephalo- itations in reproducibility, mainly owing to poor res
metric analysis (Hing, 1989; Fischer-Brandies et al, olution problems (Oliver, 1991; Ruppenthal et al,
1991; Seeholzer and Walker, 1991a, 1991b; Lew 1991; Macri and Wenzel, 1993).
1992). Furthermore, adequate data concerning the Sonic technology imaging has been introduced
interplay of the various hard and soft tissues fol during the last few years in the computerized
lowing surgery exists only for certain types or com cephalometry market and it is currently expanding
binations of osteotomies (Wolford et al, 1985; despite the high cost of the system (Alexander et al,
Phillips etal, 1986; Gjorup and Athanasiou, 1991; 1990; Chaconas et al, 1990a, 1990b). This tech
Proffit, 1991). nique works with sonic waves, thus avoiding the tra
ditional ionizing radiation. Microphones detect the
registration pen into three-dimensional space by cal
T E C H N I C A L PRINCIPLES culating the delay between the output of the sonic
wave and its detection, thereby calculating the
Computerized cephalometrics can be divided into distance from the pen to the microphone. When
two components - data acquisition and data man several microphones are used, all three-dimension
agement. al co-ordinates can be estimated.
Data acquisition is achieved by various means, The use of video imaging can be used in combi
including ionizing radiation, magnets, sound, and nation with other imaging modalities. It is used for
light (Jacobson, 1990; Isaacson et al, 1991). With profile hard and soft tissue analysis and in combi
regard to the ionizing radiation modality, the com nation with other modalities such as sonic and con
monest way of creating the x and y co-ordinates of ventional radiography. Video imaging is of special
the points is by means of a digitizer. Several papers interest because it enables inclusion and intergra-
have shown that the use of a digitizer per se does not dion with clinical photographs and dental casts
improve the reproducibility of the readings when (Jacobson, 1990).
compared to measurements obtained by manual
tracing. This is related to the fact that most of the
errors take place during the procedure of landmark CHARACTERISTICS OF THE MAIN COM
identification and not during the procedure of PUTERIZED CEPHALOMETRIC SYSTEMS
tracing (Baumrind, 1980; Richardson, 1981; Liu
and Gravely, 1991). A significant number of computerized cephalomet-
However, there is no agreement concerning the ric systems are presently available. These range from
method that is characterized by optimal repro software programmes that use one or several
ducibility when direct digitization, digitization of cephalometric analyses to comprehensive hardware
tracing, and direct manual measurement are and software packages that also perform several
compared (Downs, 1952; Richardson, 1981; auxiliary functions. A brief presentation of five of
Houston, 1982; Oliver, 1991). One of the reports the most popular systems follows: this selection does
has shown that direct manual measurements are not imply endorsement or preference of any of the
superior to direct digitization by a fivefold com systems presented here or rejection of those that are
parison of manual tracings with digitization. This absent.
way of comparison has no clinical relevance, since
the superiority of digitization is achieved through RMO's Jiffy Orthodontic Evaluation
time-saving by permitting double digitization in Rocky Mountain Orthodontics (RMO) was the first
comparison to single direct manual measurement to provide the dental profession in the late 1960s
(Oliver, 1991). with a computer-aided cephalometric diagnosis.
The recent development of computerized digital RMO Diagnostic Services Department continues to
radiography, in which the X-ray beam attenuation provide various diagnostic services, including com-
2M
Computerized Cctphalometric Systems
puterized cephalometric diagnosis and forecast of cedures (i.e. angular and linear) and it constitutes
growth and treatment. a strong tool in arranging and estimating projections
Recently, RMO has designed, created and and points.
marketed a new software package described as JOE, PorDios works with a digitizer in the standard
an acronym for Jiffy Orthodontic Evaluation. JOE way and also enables the use of a video or scanner
is a static analysis programme. According to the as means of digitization of X-rays (12.1). It uses
company's information, this software system was well-known cephalometric analyses, including
developed in response to demands for a simple Bjork, Burstone, Coben, Downs, Frontal McNam-
multi-analysis in-house system. JOE generates ara. Profile, Ricketts, Steiner, and Tweed and it has
tracings of lateral or frontal cephalograms using the capability to produce occlusograms from pho
Ricketts, Jarabak, Sassouni-plus, Steiner and tocopies of dental casts. The user of PorDios can
Grummons analyses. alter the existing programme analyses or can de
JOE can also provide a visual representation of velop his own.
normal for comparison to the patient's tracings, PorDios has built-in calculation functions for
generate a collection of cephalometric values listed showing discrepancies between the actual mean and
in a logical order along with the norms and amount its deviation from the norms. The standard devia
of deviation from normal, and put together a list tions and mean values of each cephalometric
of orthodontic problem analysis. variable can be changed by the user if different
(JOE is a product of Rocky Mountain Ortho ethnic groups have to be evaluated. The main system
dontics, PO Box 17085, Denver, Colorado 80217, can automatically alter the orientation of a picture
USA.) in order to have the profile looking to the left or
right side of the screen. PorDios is multilingual and
PorDios the user can choose from English, German, French,
PorDios (Purpose On Request Digitizer lmput Italian, Spanish, Danish and Greek.
Output System) is a cephalometric IBM-compatible The system facilitates double digitization and the
system whose development is aimed to provide mean points are calculated and stored if the distance
orthodontists with an user-friendly programme. between first and second digitization does not
This programme can be easily changed by the user exceed the user's defined maximum variation.
in order to satisfy individual preferences and needs. Therefore, with this method, any mistakes in digi
PorDios is capable of solving measuring problems tization sequence or landmark registration can be
in the two-dimensional Cartesian co-ordinate sys detected, thus ensuring the validity of the whole reg
tem. It is based on a library of mathematical pro istration procedure. During digitization, points can
12.1 PorDios works with a digitizer in

the standard way of digitization of cephalo
grams.
233
also be declared as missing or digitized at a later ulations made), CO-CR option for quantifying the
time. This is important, for example, for superim difference between the joint-dominated recorded
posing two jaws when occlusograms are produced condylar position and the tooth-dominated
and utilized together with the profile tracings. maximum intercuspal position of the mandible, and
PorDios allows the drawings to be printed either a feature that allows customization of cuts for tem-
on a matrix printer as a screen dump, on a laser poromandibular joint (TMJ) tomograms for each
printer, or on a colour plotter. The system is capable patient by means of analysing a sub-mental vertex
of understanding commands that are given using a X-ray.
template on the digitizer, so it is not necessary to use (Dentofacial Planner is a product of Dentofacial
the keyboard during digitization of the points. There Software Inc, PO Box 300, Toronto, Ontario M5X
is an import-export facility using ASCII standard, 1C9, Canada.)
and it is possible to make calculations on all stored
patients. The results of this total calculation are Quick Ceph Image
stored on a disk file and are always ready for trans Quick Ceph Image is a programme designed espe
fers (e.g. to a statistical programme). PorDios can cially for high-end Macintosh computers that does
produce a database file containing the results of the computerized cephalometrics and mapping.
digitization. This file can be read from the database Quick Ceph Image works with windows, a built-
programme each time it is started and it can import in feature in Apple computers. A Macintosh Quadra
the data and empty the file, thus making it ready or Ilci processor and a high-resolution monitor (14
to record more patients. inch, 16 inch, or 20 inch - 35 cm, 41 cm, or 51 cm)
(PorDios is a product of the Institute of Ortho should be used. The hardware also consists of a
dontic Computer Sciences, Valdemarsgade 40, DK- black-and-white camera CCD 252 (NTSC), a cam
8000 Aarhus C, Denmark.) corder Sony TR200, S-Video, a 29-inch (74-cm)
camera stand, and a colour printer.
Dentofacial Planner Thirteen different analyses can be performed,
Dentofacial Planner is a computer-aided diagnos including Ricketts, Steiner, Jarabak, McNamara,
tic and treatment planning software system for Downs, Soft Tissue, Iowa, Roth, Burstone, Sassouni,
orthodontics and orthognathic surgery. Frontal and SMV and model analyses of arch length
Dentofacial Planner works with an IBM-com and Bolton discrepancies. Four of these analyses are
patible 286 or 386 processor in DOS 3.0 or higher. reprogrammable in order to provide customized
The programme enables the user to use one of the analysis.
pre-programmed analyses, including Steiner, Other features of the system include lists of mea
McNamara, COGS, Downs, Rick 10, Rick32, surements, automatic summary description, CO-CR
Grummons, Harvold, Legan, and Jarabak. Further conversion, growth forecast, Steiner box for arch
more, the orthodontics subsystem allows the user to length discrepancy elimination, treatment simula
do superimpositions, estimate facial growth, to tions of orthodontic, orthognathic, and surgical
simulate the skeletal and soft tissue effects of movements, and superimpositions at any selected
orthopaedic appliances, and to simulate orthodon landmark and parallel to any selected line.
tic tooth movements. Quick Ceph Image allows the user to take all the
Both the orthodontics and surgery subsystems patient's pictures, including intraorals in the
allow the operator to manipulate a variety of superior 24-bit colour mode. This function is per
skeletal regions interactively. The surgery subsystem formed by means of a video camera to input up to
allows the user to estimate the skeletal and soft 16 pictures per patient at one sitting.
tissue effects of orthognathic surgery, creating a so- The system also provides an effective method for
called Surgical Treatment Objective (Wolford et al, accumulating and storing patient picture records.
1985). Recently, several innovations have been incorpo
Dentofacial Planner offers several other func rated into the system, including JPEG compression
tions, including the display of a treatment-planning for massive image storage, 32-bit addressing for fast
tracing superimposed over the load-state tracing, an operation, free-style record talking, animated treat
option for reverting the tracing to its state at load ment simulation, smile library, and the use of digi
time (thus deleting any treatment planning manip tizer or camera for the X-rays.
234
As Quick Ceph preceded Quick Ceph Image, the cephalometers. The head holder is suspended from
ater system is comparable with the earlier system. a boom, supported by a vertical column attached to
(Quick Ceph and Quick Ceph Image arc products the cabinet (12.2). Two video cameras, permanent
of Orthodontic Processing, 386 East H Street, Suite ly aimed and focused, are mounted on the vertical
209-404, Chula Vista, California 91910, USA.) column. Lighting emanates from sources inside the
boom, thus insuring that all images are properly illu
DigiGraph minated.
The DigiGraph is a synthesis of video imaging, The DigiGraph has sonic digitizing electronics
computer technology, and three-dimensional sonic and computers that enable the clinician to perform
digitizing. non-invasive and non-radiographic cephalometric
The DigiGraph Work Station equipment mea analysis. This device uses sonic digitizing electron
sures about 5 feet x 3 feet x 7 feet (152 cm x 91 cm ics to record cephalometric landmarks by lightly
x 213 cm). The main cabinet contains the electron touching the sonic digitizing probe to the patient's
ic circuitry; the patient sits next to the cabinet in skin (12.3). This emits a sound, which is then
an adjustable chair similar to those used with recorded by the microphone array in x, y, and z co-
12.2 The main cabinet contains the

e l e c t r o n i c c i r c u i t r y and the p a t i e n t sits
next t o the cabinet in an adjustable chair
similar t o those used w i t h cephalometers.
T h e head h o l d e r is s u s p e n d e d f r o m a
b o o m , supported by a vertical c o l u m n
attached to the cabinet. Two video
cameras, permanently aimed and focused,
are m o u n t e d o n t h e v e r t i c a l c o l u m n .
Lighting emanates from sources inside the
b o o m , t h u s i n s u r i n g t h a t all images a r e
properly illuminated. (Reprinted with
permission from Dolphin Imaging Systems.)
12.3 The DigiGraph has sonic digitizing

electronics and c o m p u t e r s t o enable the
clinician to perform non-invasive and non-
radiographic cephalometric analysis. This
device uses sonic digitizing electronics t o
record cephalometric landmarks by lightly
touching the sonic digitizing probe t o the
patient's skin. (Reprinted with permission
from Dolphin Imaging Systems.)
235
ordinates. According t o the manufacturer's infor • a consultation unit that t r a n s p o r t s information

mation, one can perform cephalometric analysis and into the operatory, doctor's office, or consulta
monitor patient treatment progress as often a nec tion area, thus allowing viewing and comparison
essary without radiation exposure. In addition, data of information and the development of visual
collection is non-invasive a n d , with practice, rela treatment objectives;
tively efficient. • the use of a second high-resolution video camera
The machine has the following capabilities: with a telephoto lens for taking intraoral views
• a landmark can be identified as a point in three by freeze framing the video image;
dimensions; • a light box for X-rays and a study model holder
• a cephalometric analysis can be m a d e indepen for video imaging t h a t will be included in the
dently of the head position; patient floppy disk;
• neither parallelism of the X-ray in the midsagit- • camera and video printer for producing copies ol
tal plane n o r the symmetry of a n a t o m i c mor video m o n i t o r information (Alexander et al,
phology between left and right sides is necessary 1990).
(Lim, 1992).
T h e DigiGraph also allows all a patient's radio
The basic DigiGraph Work Station's h a r d w a r e and graphs, tracings, cephalograms, photos, and models
software enable the performance of cephalometric t o be stored on one small disk, thereby reducing
analyses, tracings, superimpositions, a n d visual storage requirements. Furthermore, it is a valuable
treatment objectives. The programme produces any tool for improving communication among clinician,
of 14 cephalometric analyses including Ricketts patient and staff (12.4).
lateral, Ricketts frontal, Vari-Simplex, Holdaway, The question as to h o w similar cephalometric
A l a b a m a , J a r a b a k , Steiner, D o w n s , Burstone, measures obtained from the DigiGraph are to those
M c N a n a r a , Tweed, G r u m m o n s frontal, Standard obtained from a radiograph is of great importance
lateral, and Standard frontal. Measurements for any for the validity of the system, and an attempt to
selected analysis can be displayed on the m o n i t o r address this issue has been made by Chaconas et al
and the observed values are shown along with the (1990b). It was concluded that for the 12 cephalo
patient norm - adjusted for age, sex, race and head metric measurements used in the studies, the
size - a n d s t a n d a r d deviations from the n o r m DigiGraph Work Station digitization process
(Chaconas et al, 1990a). produced cephalometric values comparable to those
In addition to the basic DigiGraph Work Station, of cephalometric tracings, but was also quite con
there are a n u m b e r of valuable o p t i o n a l c o m p o sistent and reproducible. It remains, however, ques
nents, including: tionable how this system performs, if cephalometric
12.4 The DigiGraph is a valuable cool for

improving communications among clinician,
p a t i e n t and staff. ( R e p r i n t e d with per
mission f r o m Dolphin Imaging Systems.)
236
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work station. Part 2. Clinical Management. / Clin Fischer-Brandies E, Seeholzer H, Fischer-Brandies
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Gravely JF, Benzies PM (1991) The clinical signifi
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Grub JE (1992) Computer assisted orthognathic
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Harzer W, Reinhardt A, Dramm P, Radlinger J
Chaconas SJ, Engel GA, Gianelly AA, et al (1990) (1989) Computergestutzte Fernrontgendiagnostik
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Downs WB (1952) The role of cephalometrics in
orthodontic case analysis and diagnosis. Am J Jacobson A (1990) Planning for orthognathic
Orthod 38:162-82. surgery - art or science? Int} Adult Orthod Orthog-
nathSurg 5:217-24.
238
*
Keim RG, Economides JK, Hoffman P, Phillips HW, Phillips C, Devercux JP, Tulloch JFC, Tucker MR
Scholz RP (1992) JCO roundtables - Computers in (1986) Full-face soft tissue response to surgical max
Orthodontics. J Clin Orthod XXVI:539-50. illary intrusion. Int / Adult Orthod Orthognatb
Surg 1:299-304.
Kess K (1989) Entwicklung eines Programms zur
eomputergestutzten Fernrontgenanalyse. Die Quin- Proffit WR (1991) Treatment planning: The search
■■ tessenz 1447-51. for wisdom. In: Proffit WR, White R (eds) Surgical
Orthodontic Treatment. (Mosby Year Book: St.
I Lew KKK (1992) The reliability of computerized Louis) 142-91.
I cephalometric soft tissue prediction following
bimaxillary anterior subapical osteotomy, hit J Richardson A (1981) A comparison of traditional
Adult Orthod Orthognatb Surg 7:97-101. and computerised methods of cephalometric
analysis. EurJ Orthod 3:15-20.
Lim JY (1992) Parameters ofFacial Asymmetry and
I their Assessment. (Department of Orthodontics and Ruppenthal T, Doll G, Sergl HG, Fricke B (1991)
Pediatric Dentistry: Farmington, Connecticut.) Vergleichende Untersuchung zur Genauigkeit der
Lokalisierung kephalometrischer Referenzpimkte
Liu YT, Gravely JF (1991) The reliability of the bei Anwendung digitaler und konventioneller
Ortho Grid in cephalometric assessment. Br j Aufnahmetechnik. Fortschr Kieferortbop 52:289-96.
Orthod 18:21-7.
Seeholzer H, Walker R (1991a) Kieferorthopadische
Macri V, Wenzel A (1993) Reliability of landmark und kieferchirurgische Behandlungsplanung mit
I recording on film and digital lateral cephalograms. dem Computer am Beispiel des Dentofacial Planners
EurJOrthod 15:137-48. (I). Die Quintessenz 59-67.
Oliver RG (1991) Cephalometric analysis compar Seeholzer H, Walker R (1991b) Kieferorthopadische

ing five different methods. BrJ Orthod 18:277-83. und kieferchirurgische Behandlungsplanung mit
dem Computer am Beispiel des Dentofacial Planners
Pedersen E, Eriksen J, Gotfredsen E (1988) (II). Die Quintessenz 257-62.
Computerized Orthodontic Treatment Planning.
(Department of Orthodontics, Aarhus University: Wolford LM, Hilliard FW, Dugan DJ (1985)
Aarhus.) Surgical Treatment Oohjective; A Systematic
Approach to the Prediction Tracing. (St Louis: CV
Mosby.)
239
CHAPTER 13
Landmarks, Variables and Norms of Various Numerical

Cephalometric Analyses - Cephalometric Morphologic
and Growth Data References
Carles Bosch and Athanasios E Athanasiou
INTRODUCTION
Combinations of different cephalometric variables of the cephalometric analyses that are not present
have been made in order to form analyses ofdento- ed in this section is available. In most instances,
facial and craniofacial morphology. Most of these landmarks, variables, and norms of the various
analyses are based on established norms that have analyses are presented according to their description
been statistically derived from population samples. in the original publication. Figures from the original
Their primary use is to provide a means of com publication have been reprinted with the kind per
parison of an individual's dentofacial characteristics mission of the copyright owners. However, in some
with a population average in order to identify areas cases, owing to an evolution or alteration of part of
of significant deviation, as well as to describe the the analysis by the author, the most up-to-date
spatial relationship between various parts of the descriptions have been incorporated. For a com
craniofacial structures. prehensive understanding of the application and
interpretation of each cephalometric analysis or
In this chapter, an attempt has been made to
variable, the reader should refer to the original bib
provide this textbook with a collection of the most
liography or other relevant chapters of this
popular and best-known cephalometric analyses.
textbook.
The presentation of each analysis includes, when
available, information concerning the sample from One of the requirements for appropriate appli
where the data was derived, figure(s) with the land cation of the various cephalometric analyses is that
marks and/or variables used, the suggested norms they should be used with norms that have been
for each variable, and the corresponding original derived from groups that are the same as or similar
reference(s). This section of the book does not to the patients examined with regard to race, age,
include non-numerical analyses or the updated and sex. Therefore, in the second half of this
norms of the Coben co-ordinate craniofacial and chapter, an extensive list of references of cephalo
dentition analyses, owing to copyright protection. metric morphological and growth data based on a
However, a supplementary list of references for most variety of ethnic, age and sex groups is presented.
241
CEPHALOMETRIC ANALYSES
BELL, PROFFIT, A N D W H I T E N O R M S
Horizontal reference line

Frankfort horizontal
Variables and norms

Males and Males Females
females
Mean SD Mean SD Mean SD
Crania! base relationships

SN-Ba (saddle length) 130 ±6 (deg)
S-N length 83 ±4 77 ±4 (mm)
S-Ba length 50 ±4 46 ±4 (mm)
Ba-N length 120 ±4 112 ±5 (mm)
SN-FH 5 ±6 (deg)
Maxilla to cranium
Horizontal (anteroposterior)
SNA 82 ±4 (deg)
SN-ANS 87 ±4 (deg)
FH-NA 85 ±4 (deg)
SN-PM vert (Eth-PTM) 106 ±6 (deg)
Ba-PNS 52 ±4 50 ±4 (mm)
Ba-ANS 113 ±5 106 ±5 (mm)
Vertical
Na-ANS 60 ±4 56 ±3 (mm)
Or-Pal plane 27 ±3 25 ±2 (mm)
Eth-PNS 55 ±4 50 ±3 (mm)
Internal maxillary measurements

PNS-ANS 62 ±4 57 ±4 (mm)
PTM-ANS 65 ±3 61 ±4 (mm)
PM vert-A (perpendicular) 59 ±3 57 ±4 (mm)
Mandible to cranium
SNB 79 ±3 (deg)
SN-Pog 79 ±3 (deg)
NPog-FH (Facial plane) 85 ±5 83 ±4 86 ±3 (deg)
FH-NB 82 ±3 . (deg)
NPog-Mandibular plane 68 ±3 (deg)
Ba-Gn 128 ±5 120 ±6 (mm)
242
Internal mandibular measurements
Co-B
Co-Pog
Co-Gn (ramus length)
Go-B
Go-Gn (body length)
Ramus thickness at midpoint
Co-Mandibular plane perpendicular
Mandible to maxilla
ANB 3
Palatal plane-NB 85
Palatal plane-BPog 86
Palatal plane - Mandibular plane 82
Co-PNS
Maxillary teeth to other structures

i-NA 22
1-NA 4
Maxillary arch length
(mesial 6—labial 1)
ANS-1
Palatal plane-1
Palatal plane-£
1-SN 104
1-FH 109
1-Palatal plane 112
Palatal plane - Functional occlusal plane 7
Mandibular teeth to other structures
l-APog
1-NB
1-SN 52
1-FH 56
1-Palatal plane 59
1-Mandibular plane 95
l-APog 24
1-NB 25
Go-lower incisor incisal edge
Mandibular arch length
6-Mandibular plane
1-Mandibular plane
Id-Me
Males and Males Females

females
Chin prominence
Pog-NB 2 ±2 (mm)
Maxillary to mandibular teeth

1-Uppcr incisor 129 ±10 (deg)
l_-Functional occlusal plane 61 ±7 (deg)
Upper incisor-
Functional occlusal plane 67 ±7 (deg)
Vertical dentofacial relationships

SN-Palatal plane 7 ±3 (deg)
SN-Functional occlusal plane 14 ±4 (deg)
SN-GoGn 32 ±5 (deg)
SN-Ramus plane 89 ±4 (deg)
FH-Functional occlusal plane 11 ±3 (deg)
FH-Ramus plane 85 ±4 (deg)
Palatal plane-NA 88 ±4 (deg)
Ramus plane-Mandibular plane 123 ±5 (deg)
Me-ANS 80 ±6 70 ±5 (mm)
Me-Palatal plane perpendicular 76 ±6 67 ±4 (mm)
Me-Ne 137 ±8 123 ±5 (mm)
S-PNS 56 ±4 51 ±3 (mm)
S-ANS 100 ±5 93 ±6 (mm)
S-Gn 144 ±7 131 ±5 (mm)
S-Go 88 ±6 80 ±5 (mm)
References
Bell WH, Proffit WR, White RP (1980) Surgical
Correction of Dentofacial Deformities, volume I.
(WB Saunders: Philadelphia)137-50.
244
Landmarks* Variables^ Analyses and Norms
BJORK ANALYSIS (13.1)
ongin Group II - boys from the town of race Scandinavian (Swedish)

Vasteraas, Sweden sex Males
Group III - army conscripts (n=215) clinical characteristics
from the Dalkarlia Regiment drawn Group II - very good condition of the
from the entire population of this area teeth, only single permanent teeth
and voluntary high school graduates decayed or single teeth missing, no
(n=66) orthodontic treatment
size and age Group III - cases with fixed bridges,
Group 1 - 2 0 twelve-year-old removable dentures and completely
Group II - 322 twelve-year-old decayed bite were excluded. None of the
Group III - 281 conscripts and high conscripts had received orthodontic
school graduates treatment
1 3 . 1 L a n d m a r k s and t h e i r d e f i n i t i o n s u s e d in t h e Bjork
cephalometric analysis-
a - articulare - the point o f intersection of the dorsal contours o f
processus articularis mandibulae and os temporale. The midpoint
is used where double projection gives rise t o t w o articulare points,
dd - the m o s t p r o m i n e n t point of the chin in the direction of
measurement.
gn - gnathion - the deepest point o n the chin.
id - infradentale - the point of transition from the crown of the most
prominent mandibular medial incisor t o the alveolar projection,
ii - incision inferius - the incisal p o i n t of the most p r o m i n e n t
medial mandibular incisor
is - incision superius - the incisal point of the most prominent
medial maxillary incisor.
k k - the p o i n t of i n t e r s e c t i o n b e t w e e n t h e base and ramus
tangents t o the mandible. The midpoint is used w h e r e double
projection gives rise t o t w o points.
mi - the mesial contact point of the lower molar projected normal
t o the plane of occlusion.
ms - the mesial contact point of the upper molar projected normal
t o the plane of occlusion.
n - nasion - the anterior limit of sutura nasofrontalis.
o r - orbitale - the deepest point o n the infraorbital margin. The
midpoint is used where double projection gives rise t o t w o points,
pg - pogonion - the most prominent point o n the chin,
po - porion - the midpoint on the upper edge of porus acusticus
externus, located by means of the metal rods o n the cephalometer.
This is a cephalometric reference point.
p r - prosthion - t h e transition point between the c r o w n o f the
m o s t p r o m i n e n t m e d i a l m a x i l l a r y i n c i s o r and t h e a l v e o l a r
projection.
s - the centre of sella turcica (the midpoint of the horizontal diameter),
Horizontal reference line sm - supramentale - the deepest p o i n t o n the c o n t o u r of the
Sella-nasion line alveolar projection, between infradentale and pogonion.
sp - the spinal point - the apex of spina nasalis anterior,
snp - spina nasalis posterior - the point of intersection of palatum
posterior durum, palatum molle and fossa pterygo-palatina.
ss - subspinale - the deepest point o n the c o n t o u r of the alveolar
projection, between the spinal point and prosthion.
io - the incisal point of the most prominent medial mandibular
incisor, projected normal t o the plane of occlusion.
245
Variables and norms
Mean SD
Dentobasal relationships
Sagittal
Dentoalveolar
Maxillary alveolar prognathism (pr-n-ss) 2 ±1 (deg)
Mandibular alveolar prognathism (CI7ML) 70 ±6 (deg)
Maxillary incisor inclination (ILs/NL) 110 ±6 (deg)
Mandibular incisor inclination (II.i/ML) 94 ±7 (deg)
Basal
Sagittal jaw relationship
(ss-n-pg) 2 ±2.5 (deg)
(ss-n-sm) 3 ±2.5 (deg)
Vertical
Dentoalveolar
Maxillary zone (NIYOLs) 10 ±4 (deg)
Mandibular zone (OLi/ML) 20 ±5 (deg)
Basal
Vertical jaw relationship (NL/ML) 25 ±6 (deg)
Cranial relationships
Sagittal
Basal
Maxillary prognathism 82 ;3.5 (deg)
Mandibular prognathism 80 3-5 (deg)
Vertical
Basal
Maxillary inclination (NL/OLs) 8 ±3 (deg)
Mandibular inclination (OLi/ML) 33 ±6 (deg)
Growth zones
Cranial base
n-s-ar 124 ±5 (deg)
n-s-ba 131 ±4.5 (deg)
Mandibular morphology
p-angle to ar 19 ±2.5 (deg)
Jaw angle 126 ±6 (deg)
References
Bjork A (1947) The face in profile. Sven Tandlak Bjork A (1960) The relationship of the jaws to the
Tidskr 40(suppl5B). cranium. In: Lundstrom A (ed) Introduction to
Orthodontics (McGraw-Hill: New York) 104-40.
246
Landmarks, Variables, Analyses and Norms
BURSTONE A N D COWORKERS' ANALYSIS FOR O R T H O G N A T H I C SURGERY (13.2)
•ample
-r^€^
origin sample obtained from the Child sex 14 males
Research Council of the University of 16 females
Colorado School of Medicine age 5-20
30M characteristics
longitudinal sample
N-A P3
13.2 Left: Horizontal skeletal angle of convexity. Right: Horizontal Measurements o f length o f maxilla and mandible (C).
skeletal profile (A). Vertical skeletal and dental measurements (B). Measurements of dental relations (D).
(From Burstone etal.1979; reprinted with permission.)
247
H o r i z o n t a l r e f e r e n c e line
Constructed by drawing a line through nasion 7 degrees up from sella-nasion line
Variables a n d n o r m s
Males Females
Mean S.D. Mean S.D.
Cranial base
Ar-PTM (HP) 37.1 ±2.8 32.8 ±1.9 mm,
PTM-N (HP) 52.8 ±4.1 50.9 ±3.0 mm
Horizontal (skeletal)
N-A-Pg angle 3.9 ±6.4 2.6 ±5.1 (deg;
N-A (HP) 0.0 ±3.7 -2.0 ±3.7 (mm;
N-B (HP) -5.3 ±6.7 -6.9 ±4.3 (mm]
N-Pg (HP) -4.3 ±8.5 -6.5 ±5.1 (mm]
Vertical (skeletal, dental)

N-ANS (_ HP) 54.7 ±3.2 50.0 ±2.4 (mm)
ANS-Gn (_ HP) 68.6 ±3.8 61.3 ±3.3 (mm)
PNS-N (_ HP) 53.9 ±1.7 50.6 ±2.2 (mm)
MP-HP angle 23.0 ±5.9 24.2 ±5.0 (deg)
Upper incisor-NF (_ NF) 30.5 ±2.1 27.5 ±1.7 (mm)
Lower incisor-MP (_ .MP) 45.0 ±2.1 40.8 ±1.8 (mm)
Upper molar-NF (_ NF) 26.2 ±2.0 23.0 ±1.3 (mm)
Lower molar-MP (_ MP) 35.8 ±2.6 32.1 ±1.9 (mm)
Maxilla, mandible
PNS-ANS (HP) 57.7 ±2.5 52.6 ±3.5 (mm,
Ar-Go (linear) 52.0 ±4.2 46.8 ±2.5 (mm;
Go-Pg (linear) 83.7 ±4.6 74.3 ±5.8 (mnt
B-Pg (MP) 8.9 ±1.7 7.2 ±1.9 (mm;
Ar-Go-Gn angle 119.1 ±6.5 122.0 ±6.9 (deg;
Dental
OP upper-HP angle 6.2 ±5.1 7.1 ±2.5 (deg)
OP lower-HP angle **• • •« (deg)
A-B (OP) -1.1 ±2.0 -0.4 ±2.5 (mm)
Upper incisor-NF angle 111.0 ±4.7 112.5 ±5.3 (deg)
Lower incisor-MP angle 95.9 ±5.2 95.9 ±5.7 (deg)
Referencs
Burstone CJ, James RB, Legan H, Murphy GA,
Norton LA (1979) Cephalometrics for orthognath-
ic surgery. 7 Oral Surg 36:269-77.
248
COBEN CRANIOFACIAL A N D DENTITION ANALYSES (BASION HORIZONTAL) (13.3,

13.4)
13.3 Landmarks and t h e i r definitions used in the Coben

craniofacial cephalometrk analysis, as illustrated in the figures
analysing cranial base (A), face depth (B) and face height (C),
respectively:
A - point A (subspinale) - the point at the deepest midline
concavity on the maxilla between the anterior nasal spine and
prosthion.
Ans - anterior nasal spine - the most anterior point of the
anterior nasal spine.
A r - articulate - the point of intersection of the images of the
posterior border of the condylar process of the mandible and the
inferior border of the basilar part of the occipital bone.
B - point B (supramentale) - the point at the deepest midline
concavity on the mandibular symphysis between infradentale and
pogonion.
Ba - basion - the median point of the anterior margin of the
foramen magnum located by following the image of the slope of
the inferior border of the basilar part of the occipital bone to its
posterior limit.
249
F — p o i n t F ( c o n s t r u c t e d ) - the p o i n t a p p r o x i m a t i n g f o r a m e n auditory meatus (superior margin of temporomandibular fossa,

caecum representing the anatomic a n t e r i o r limit of the cranial which lies at the same level, may be substituted in the construction
base, constructed as the point of intersection of a perpendicular t o of Frankfort horizontal).
the S - N plane f r o m the p o i n t o f crossing of the images of the Po - pogonion - the most anterior midline point of the mandibular
orbital roofs and the internal plate of the frontal bone. symphysis.
G o - gonion (constructed) - the point of intersection of the ramus P o ' - p o g o n i o n ' ( c o n s t r u c t e d ) - the p o i n t o f tangency of a
plane and the mandibular plane. perpendicular from the mandibular plane t o the most prominent
M - menton — the most inferior midline point o n the mandibular convexity of the mandibular symphysis.
symphysis. Ptm - pterygomaxillary fissure - the point of intersection of the
N - nasion - the most anterior (midline) point of the frontonasal images o f the anterior surface of the p t e r y g o i d process of the
suture. sphenoid bone and the posterior margin of the maxilla.
O - orbitale - the lowest point o n the inferior margin of the orbit, S - sella - the point representing the geometric centrer of the
midpoint between right and left images. pituitary fossa (sella turcica).
P - p o r i o n ( a n a t o m i c ) - t h e s u p e r i o r p o i n t o f the e x t e r n a l (From Coben, 1986; reprinted w i t h permission.)
13.4 Landmarks and their definitions used in the Coben dentition

cephalometric analysis:
Ul
- maxillary central incisor (horizontal) - the most labial point on
the crown of the maxillary central incisor;
- maxillary c e n t r a l incisor (vertical) — the incisal edge of the
maxillary central incisor.
LI
- mandibular central incisor (horizontal) - the most labial point
on the c r o w n of the mandibular central incisor;
- mandibular central incisor (vertical) - the incisal edge of the
mandibular central incisor.
U6
- maxillary first molar (horizontal) — the most distal point on the
c r o w n of the maxillary first permanent molar;
- maxillary first molar (vertical) - the tip of the mesiobuccal cusp
of the maxillary first permanent molar.
L6
- mandibular first molar (horizontal) - the most distal point on
the c r o w n of the mandibular first permanent molar;
- mandibular first molar (vertical) - the tip of the mesiobuccal
cusp of the mandibular first permanent molar.
(From Coben, 1986; reprinted with permission.)
250
Landmarks, Variables* Analyses and Norms
Horizontal reference line grated concept of craniofacial growth by which

Basion horizontal growth variables are mathematically summated to
calculate their combined effect on the spatial
Variables and n o r m s (Tables 13.1, 13.2) position of the dentition and the size and form of
The up-to-date complete sets of norms of the Coben the total face and profile. Furthermore, these
co-ordinate craniofacial and dentition analyses are analyses do not constitute a morphological evalua
not included in this section due to copyright pro tion or a combination of random measurements, but
tection. a totally integrated philosophy of craniofacial
According to Coben,"the illustrations of the growth and a system of analysis that depicts this
analyses should not be separated from the super philosophy".
imposed tracings since the work is a totally inte
Table 13.1 Means and variability of craniofacial proportions of 47 children at the age of 8 years ± I year (Coben, 1955).
251
BOYS GIRLS
MEAN AGE SPAN: 7.72 YEARS MEAN AGE SPAN: 7.66 YEARS
STANDARD STANDARD
UNIT MEAN DEVIATION RANGE UNIT MEAN DEVIATION RANGE
9.6 2.14 5.5/13.0 mm 7.4 2.36 3.0/12.0
0.0/5.5 mm 3.0 1.57 0.0/7.0

0.0/4.0 mm I.I 1.30 0.0/5.5
3.0/9.5 mm 11 1.39 1.5/6.0
6.0/17.5 mm 8.2 2.17 3.0/13.5
-2.5/3.0 mm 0.0 1.09 -2.5/2.0

8.0/25.0 mm J_L5 3.03 7.5/17.5
7.5/28.0 mm 11.5 3.01 7.5/17.5
6.5/19.5 mm 9.1 2.15 4.5/13.0

-6.0/+4.0 o -02 2.67 -4.0/+5.0
-2.5/4.5 1.2 2.14 -2.0/5.0
mm
7.0/26.5 9.5 2.58 5.0/15.5
-8.0/+4.0 mm -4.1 2.16 -8.0/0.0
6.5/25.0 o 10.3 2.71 6.5/18.0
mm
I0.0/+I.0 o -4.8 3.07 -9.0/+3.0
-8.0/+4.0 o -4.1 2.16 -8.0/0.0
-6.0/+4.0 0 -0.7 2.67 -4.0/+5.0
0.0/2.5 mm 0.6 0.50 0.0/1.5
0.5/9.0 mm 2.8 1.45 0.5/6.0

5.5/20.5 mm ?J. 2.08 5.5/13.0
.0/28.0 mm 11.9 3.17 4.5/19.0
0.0/18.5 mm 57 2.13 0.0/9.5

-0.5/8.5 mm 2.6 1.81 -0.5/6.0
3.5/13.5 mm 4.4 1.69 1.0/8.5
-3.0/4.5 mm 1.45 -1.5/4.5
3,0/18.5 mm 5.8 2.85 -1.5/11.0
10.5/37.0 mm 11.5 3.14 7.0/19.0
Table 13.2 Means and variability of increments in craniofadal depth and height of 25 boys and 22 girls f r o m ages 8 years ± I year to 16
years ± I year (Coben, 1955).
References
Coben SE (1955) The integration of facial skeletal Coben SE (1986) Basion Horizontal. (Computer
variants. Am) Orthod 41:407-434. CephaJometrics Associated; Jenkintown, Pennsyl
vania.)
Coben SE (1979) Basion Horizontal Coordinate
Tracing Film./ C/m Orthod 13:598-605.
252
Dl PAOLO'S QUADRILATERAL ANALYSIS (13.5)
Sample age mean 12.6

size 245 range 9-15
race not reported clinical characteristics
sex equally divided untreated orthodontic patients with
normal occlusions
13.5 Quadrilateral analysis. Dental assessment (BJ:

Skeletal assessment (A): 1 Pogonion line
Max Lth - maxillary base length 2 Point A line
Mand Lth - mandibular base length 3 Point B line
AUFH - anterior upper facial height 4 Anterior lower facial height
ALFH - anterior lower facial height (From Di Paolo et al. 1983; reprinted with permission.)
PLFH - posterior lower facial height
Facial - angle of facial convexity
H o r i z o n t a l r e f e r e n c e line
Sella—nasion line
253
Variables and n o r m s
Linear and angular
Mean S.D.
Maxillary length 50.9 2.0 (mm)

Mandibular length 50.0 2.5 (mm)
Difference 0.9 N/M (mm)
ALFH
(Anterior lower facial height) 60.0 3.5 (mm)
PLFH
(Posterior lower facial height) 39.4 2.2 (mm)
LFH (average)
(Lower facial height) 49.7 2.8 (mm)
AUFH
(Anterior upper facial height) 49.2 2.3 (mm)
Posterior LEG (max) 101.4 N/M (mm)
Total length (max) 152.3 N/M (mm)
PP-GoGn angle 23.1 1.7 (deg)
Facial convex angle 169.5 3.2 (deg)
Ratios
Mean
Maxillary length/mandibular length 1 : 0.99

Maxillary length/LFH (average) I : 0.99
ALFH/AUFH 1 : 1.21
Posterior LEG (max)/total length (max) 1 : 1.5
(sagittal ratio)
PLFH/ALFH (vertical ratio) 1 : 1.52
References
Di Paolo RJ (1969) The quadrilateral analysis, Di Paolo RJ, Philip C, Maganzini AL, Hirce JD
cephalometric analysis of the lower face. / Clin (1983) The quadrilateral analysis: an individualized
Orthod 3:523-30. skeletal assessment. Am J Orthod 83:19-32.
Di Paolo RJ, Markowitz JL, Castaldo DA (1970) Di Paolo RJ, Philip C, Maganzini AL, Hirce JD
Cephalometric diagnosis using the quadrilateral (1984) The quadrilateral analysis: a differential
analysis. 7 Clin Orthod 4:30-5. diagnosis for surgical orthodontics. Am ] Orthod
86:470-82.
254
Landmarks, Variables* Analyses and Norms
DOWNS ANALYSIS (13.6, 13.7)
size 20 individuals age 12-17

race Caucasian clinical characteristics
sex male and female about equally divided clinically excellent occlusion
13.6 Landmarks, planes, and variables of the Downs cephalo

metric analysis.
Nasion - the suture between the frontal and nasal bones.
Bolton point - the highest point on the concavity behind the
o c c i p i t a l COndyles.
The centre of sella turcica - located by inspection of the profile
image of the fossa.
Orbitale - the lowest point on the left infraorbital margin.
Porion (cephalometric) - the highest point on the superior surface
of the soft tissue of the external auditory meati.
Pogonion - the most anterior point on the mandible in the midline.
Point A - subspinale - the deepest midline point on the premaxilla
between the anterior nasal spine and prosthion.
Point B - supramentale - the deepest midline point on the
mandible between infradentale and pogonion.
Gnathion - a point on the chin determined by bisecting the angle
formed by the facial and mandibular planes,
Bolton plane - represented by a line from nasion to Bolton point.
Frankfort horizontal (cephalometric) - a horizontal plane running
through the right and the left cephalometric porion and the left
orbitale.
Mandibular plane - a line at the lower border of the mandible
tangent to the gonion angle and the profile image of the symphysis.
Facial plane - a line from nasion to pogonion.
Denture base limit — a line drawn through points A and B.
Occlusal plane - a line bisecting the occlusion of the first molars
and central incisors. Should either incisor lack full eruption or be
in supraclusion o r infraclusion, the general occlusion as determined
by the premolars is used.
Y axis - a line from sella turcica to gnathion.
Angle of convexity - formed by the intersection of a line from
nasion to point A with a line from point A to pogonion.
Facial angle - the inside inferior angle formed by the intersection
of the Frankfort horizontal and facial plane.
(From Downs, 1948; reprinted with permission.)
255
retrogndthic prognathic
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13.7 Polygonic interpretation of the findings of Downs analysis. (From Vorhies and Adams, 1951; reprinted with permission.)
256

Variables and norms

Mean SD Range
Skeletal
Facial angle 87.8 ±3.57 82-95 (deg)
Angle of convexity 0 ±5.09 -8.5 to 10 (deg)
AP plane to facial plane -4.6 ±3.67 -9to0 (deg)
Mandibular plane angle 21.9 ±3.24 17-28 (deg)
Y axis to Frankfort horizontal 59.4 ±3.82 53-66 (deg)
Dental
Cant occlusal plane 9.3 ±3.83 1.5-14 (deg)
Interincisal angle 135.4 ±5.76 130-150.5 (deg)
Inclination incisor inferior to occlusal plane 14.5 ±3.48 3.5-20 (deg)
Inclination incisor inferior to mandibular plane 91.4 ±3.78 -8.5 to 7 (deg)
Inclination incisor superior to AP plane 2.7 ±1.8 -1 to 5 (mm)
References
Downs WB (1948) Variation in facial relationships: Downs WB (1956) Analysis of the dentofacial
their significance in treatment and prognosis. Am J profile. Angle Orthod 26:191-212.
Orthod 34:812-40.
Vorhies JM, Adams JW (1951) Polygonic
Downs WB (1952) The role of cephalometrics in interpretation of cephalometric findings. Angle
orthodontic case analysis and diagnosis. Am J Orthod 21:194-7.
Orthod 38:162-82.
257
FARKAS A N D COWORKERS' ANALYSIS (INCLINATIONS OF THE FACIAL PROFILE) (13.8)
sex 51 males
50 females
age 18-30 years
clinical characteristics
subjects were randomly selected healthy
individuals, all hospital employees, office
workers, or students without visible
occlusion problems
13.8 Nine landmarks identifying the individual

segments of the facial profile contour,
t r i c h i o n ( t r ) - p o i n t o n t h e hairline in the
midline of the forehead
TRJCHON (Tr) glabella (g) - the most prominent midline point
between the eyebrows
subnasion (n') - deepest point of the nasofrontal
angle
pronasale (prn) - the most protruded point of
DEEPEST POINT Of THE the apex nasi
NASOFRONTAL ANGLE (n'l
FRANKFURT HORIZONTAL subnasale (sn) - midpoint of the columella base
at the apex of the nasolabial angle
PRONASALE (pm) labiale superius (Is) — m i d p o i n t of the upper
vermilion line
SUBNASALE (
labiale i n f e r i u s (li) - m i d p o i n t o f the lower
vermilion line
LABIALE INFERIUS (li) sublabiale (si) - m i d p o i n t of the horizontal
labiomental skin ridge
POGONtON(pg> pogonion (pg) - the most anterior midpoint of
the chin.
(From Farkas e t al, 1985; reprinted with per
mission.)
258

Males Females
Mean SD Mean SD n
Basic facial inclinations

General (g-pg) -4.7 ±3.1 -4.9 ±3.8 131 (cleg)
Aesthetic (n'-pg) -5.5 ±3.8 31 (deg)
Upper face (g-sn) 1.3 ±3.5 -0.1 ±5.9 50 (deg)
Lower face (sn-pg) 16.2 ±5.8 -14.1 ±5.9 100 (deg)
Lower third of face (li-pg) 21.3 ±7.3 -18.9 ±6.7 100 (deg)
Profile segment inclinations

Forehead (tr-g) 10.5 ±6.3 -5.5 ±5.9 50 (deg)
Nasal bridge (n'-prn) 29.5 ±5.1 29.6 ±3.7 50 (deg)
Upper lip (sn-ls) -1.9 ±9.1 -0.7 ±7.2 100 (deg)
Lower lip (li-ls) 51.0 ±12.0 7.2 ±11.9 50 (deg)
Chin (sl-pg) 12.2 ±8.0 12.3 ±8.7 50 (deg)
Reference
Farkas LG, Sohm P, Kolar JC, Katie MJ, Munro IR
(1985) Inclinations of the facial profile: art versus
reality. Plast Reconst Surg 75:509-19.
259
HARVOLD ANALYSIS (13.9)
Sample
origin Data derived from white children studied race white

at the Burlington Orthodontic Research
Center, University of Toronto, Canada clinical characteristics
size, age, and sex distribution not specified
6 years-
9 years-
12 years-
14 years-
6 years- 53
13.9 Cephalometric tracing of a case using Harvold cephalometric

analysis. The following landmarks and measurements are used in
this analysis:
Temporomandibular joint (TMJ) - a point on the contour of the
glenoid fossa, where the line indicating the maximum length of the
mandible intercepts the contour of the temporomandibular fossa.
The midpoint between the right and left side is marked.
Anterior nasal spine (ANS) - a point on the lower contour of the
anterior nasal spine where the vertical thickness is 3 mm, used for
horizontal measurements; a point on the upper contour of the
anterior nasal spine, where the vertical thickness is 3 mm,
employed for vertical measurements.
Prognathion (PGN) — a point on the contour of the chin indicating
maximum mandibular length measured from the
temporomandibular joint.
Gnathion (GN) - the most inferior point on the contour of the
chin.
Pogonion (PG) - the most anterior point on the chin.
Nasion (N) - the point at which the nasofrontal suture reaches the
contour line of the bones.
The forward position of the maxilla, measured from TM to ANS.
Mandibular length, measured from TM to PGN.
Lower face height, measured from ANS to GN.
The angle of convexity - the angle between the lines PG-ANS and
ANS-N.
(From Harvold, 1974; reprinted with permission.)
260
Variables and norms

Mean SD
Angle of convexity (Pg-ANS/ANS-N) Not specified

Interincisal angle 128 ±4 (deg)
Occlusal plane / line through the roots of the
maxillary and mandibular central incisors 89 ±5 (deg)
4
Length of the jaws and lower face height

Girls Boys
Mean SD Mean SD
6 years
Forward position of the maxilla (TM to ANS) 80 ±2.96 82 ±3.19 (mm)
Mandibular length (TM to Pg) 97 ±3.55 99 ±3.85 (mm)
Lower face height (ANS-Gn) 57 ±3.22 59 ±3.55 (mm)
Difference in jaw length 17 17 (mm)
•
9 years
12 years
14 years
16 years
Reference
Harvold EP (1974) The Activator in Orthodontics.
(CV Mosby: St Louis) 37-56.
261
HASUND (BERGEN) ANALYSIS (13.10)
depending on the measurement and it

between 48 and
av,an
13.10 Planes used in the Bergen analysis.

(From Hasund, 1977; reprinted with per
mission.)
262

Sella-Nasion line
Variables and norms

Mean Range
Angular measurements
Group 1
SNA 82.1 74-90 (deg)
SNB 80 72.5-88 (ckg)
ANB 2.5 -4.5 to 8.5 (deg)
SNPg 82 74.5-90.5 (deg)
Group II
SNBa 129 119-139 (deg)
Mandibular angle (Gn-tgo-Ar) 126 112-151 (deg)
NORDF.RVAL ANGLE (N angle) 56.3 40-74 (deg)
Group HI
NL-NSL 8 2.5-14 (deg)
ML-NSL 29 13^11.5 (deg)
ML-NL 21 9-33.5 (deg)
Group IV
Interincisal angle 139 120-163 (deg)
Upper incisor to NA angle 18 0-37 (deg)
Upper incisor to NB angle 22 2-40 (deg)
Group V
Holdaway angle (NB-Pg to UL) 3-18 (deg)
Linear measurement
Croup I
Upper incisor to NA distance 3.5 -4 to 9 (mm
Upper incisor to NB distance 4 -9 to 14.5 (mm
Pg to NB distance 4 0-11.5 (mm
Holdaway ratio difference 0 -11 to 13 (mm
Group 11
Anterior facial height 79 65-101 (m m
Upper facial height (N-SP') not specified (m m
Lower facial height {Sp'-Gn) not specified (mm
Index in percent N-Sp' x 100 not specified
Sp'-Gn
References
Hasund A, Sivertsen R (1969) An Evaluation of the Hasund A (1977) Clinical cephalometry for the
Diagnostic Triangle in Relation to the Facial Type, Bergen technique. Orthodontic Department, Dental
the Inclination of the Horizontal Facial Planes and Institute, University of Bergen: Bergen.)
the Degree of Facial Prognathism. (Acta Universit
Bergensis, Mcdisinske Avhandl: Bergen.)
263
H O L D A W A Y ANALYSIS (13.11)
Sample
origin private practice patients sex not specified

age not specified
race Northern European ancestry
13.11 In the Holdaway analysis the following lines are used:

1 the H line o r harmony line drawn tangent t o the soft tissue
chin and the upper lip
2 a soft tissue facial line f r o m soft-tissue nasion t o the point on
the soft tissue chin overlying Ricketts' suprapogonion
3 the usual hard tissue facial plane
4 the sella-nasion line
5 Frankfort horizontal plane (FH)
6 a line running at a right angle t o the Frankfort plane down
tangent t o the vermilion border of the upper lip
(From Holdaway, 1983; reprinted with permission.)
H o r i z o n t a l reference line
Soft tissue facial angle (A) 91±7 fdeg

Nose prominence (B) range: 14 to 24 (mm
Superior sulcus depth (Q 3 (range: 1 to 4) (mm
Soft tissue subnasale to H line (D) 5±2 (mm
Skeletal profile convexity (E) 0 (mm
Basic upper lip thickness (F) ■ 3
:
(mm]
Upper lip strain (G) 13 to 14 (mm)
H angle (H) 10 (best range: 7 to 14)* (deg)
Lower lip to H line (I) 0-0.5 (range: -1 to 2) ''mm
Inferior sulcus to H line (J) No norms
Soft tissue chin thickness (K) 10-12 mm
* Depending on the skeletal profile convexity present
References
Holdaway RA (1983) A soft-tissue cephalometric Holdaway RA (1984) A soft-tissue cephalometric
analysis and its use in orthodontic treatment analysis and its use in orthodontic treatment
planning. Part I. Am J Orthod 84:1-28. planning. Part II. Am] Orthod 85:279-93.
264
JARABAK ANALYSIS (13.12)
Sample
origin some of the measurements were described race not specified

and taken from Bjork cephalometric sex not specified
analysis age not specified
size not specified
SNA 81°
SNB 88°
D. C. ANB -7°
Face Height Ratio SN-Po 92°
6- 9-55 71%
9-17-70
24°
43ram
127mm
19'
52mm
14'
13.12 Cephalometric tracing of the Jarabak analysts. (From Jarabak and Fizzell, 1972; reprinted with
permission.)
265
Sella-nasion line
Variables and norms

Mean S.D
Skeletal analysis
Saddle angle (N-S-Ar) 123 ±5 (deg)
Articular angle (S-Ar-Go) 143 ±6 (deg)
Gonial angle (Ar-Go-Gn) 130 ±7 (deg)
Sum 396 (deg)
Anterior cranial base length 71 ±3 (mm)
Posterior cranial base length 32 ±3 (mm)
Gonial angle (N-Go-Ar) 52-55 (deg)
Gonial angle (N-Go-Gn) 70-75 (deg)
Ramus height (Ar-Go) 44 ±5 (mm)
Body length (Go-Gn) 71 ±5 (mm)
Mandibular body /
anterior cranial base length ratio 1/1
SNA 80 ±1 (deg)
SNB 78 ±1 (deg)
ANB 2 (deg)
SN GoGn not specified (deg)
Facial depth (N-Go) not specified (mm)
Facial length on Y axis not specified (mm)
Y axis to SN not specified (deg)
S Go post facial height not specified (mm)
Anterior facial height not specified (mm)
Posterior facial / anterior facial height not specified %
Facial plane (SN-Po) not specified (deg)
Facial convexity (NA-Po) not specified (deg)
Denture analysis
Occlusal plane to Go-Gn not specified (deg)
Interincisal angle not specified (deg)
Upper incisor to Go-Gn 90 ±3 (deg)
Upper incisor Go-Gn not specified (mm)
ItoSN 102 ±2 (deg)
1 to facial plane (N-Po) 5 ±2 (mm)
Upper incisor to facial plane (N-Po) -2 to +2 (mm)
Facial aesthetic line upper lip -1 to -4 (mm)
Facial aesthetic line lower lip 0to2 (mm)
Reference
Jarabak JR, Fizzell JA (1972) Technique and
Treatment with Lightwire Edgewise Appliance. (GV
Mosby: St Louis.)
266
LEGAN A N D BURSTONE SOFT TISSUE ANALYSIS FOR ORTHOGNATHIC SURGERY

(13.13)
characteristics
orthodonticaily untreated patients with
Class I occlusions and vertical facial
proportions that were determined to be
within normal limits (N-ANS/ANS-Me
between 0.75 and 0.85)
13.13 Landmarks used in the Legan and Burstone soft tissue

analysis.
Glabella (G) - the most prominent point in the midsagittal plane of
the forehead
Columella point (Cm) - the most anterior point on the columella
of the nose
Subnasale (Sn) - the point at which the nasal septum merges with
the upper cutaneous lip in the midsagittal plane
Labrale superius (Ls) - a point indicating the mucocutaneous
border of the upper lip
Stomion superius (Stms) - the lowermost point on the vermilion
of the upper lip
Stomion inferius (Stmi) - the uppermost point on the vermilion of
the lower lip
Labrale inferius (Li) - a point indicating the mucocutaneous border
of the lower lip
Mentolabial sulcus (Si) - the point of greatest concavity in the
midline between the lower lip (Li) and chin (Pg')
Soft tissue pogonion (Pg') - the most anterior point on soft tissue
chin
Soft tissue gnathion (Gn') - the constructed midpoint between soft
tissue pogonion and soft tissue menton; can be located at the
intersection of the subnasale to soft tissue pogonion line and the
line from C to Me*
Soft tissue menton (Me') - the lowest point on the contour of the
soft tissue chin; found by dropping a perpendicular from horizontal
plane through menton
Cervical point (C) - the innermost point between the submental
area and the neck located at the intersection of lines drawn
tangent to the neck and submental areas
Horizontal reference plane (HP) — constructed by drawing a line
through nasion 7 degrees up from setla-nasion line
(From Legan and Burstone, 1980; reprinted with permission.)
267

Constructed by drawing a line through nasion
7 degrees up from sclla-nasion line
Mean S.D.
Facial form
Facial convexity angle (G-Sn-Pg') 12 ±4 (cleg)
Maxillary prognathism (G-Sn (HP*)) 6 ±3 (mm;
Mandibular prognathism (G-Pg'(HP*)) 0 ±4 (mm]
Vertical height ratio (G-Sn/Sn-Me'(HP+)) 1
Lower face-throat angle (Sn-Gn'-C) 100 ±7 (deg)
Lower vertical height-depth ratio (Sn-GnVC-Gn') 1.2
Lip position and form

Nasolabial angle (Cm-Sn-Ls) 102 ±8 (deg)
Upper lip protrusion (Ls to (Sn-Pg')) 3 ±1 (mm;
Lower lip protrusion (Li to (Sn-Pg1)) 2 ±1 (mm;
Mentolabial sulcus (Si to (Li-Pg')) 4 ±2 (mm;
Vertical lip-chin ratio (Sn-Stms/Stmi-Me'(HP+)) 0.5
Maxillary incisor exposure (Stm s/1) 2 ±2 (mm;
Interlabial gap (Stms-Stmi (HP+)) 2 ±2 (mm
*(HP) - refers to parallel to Horizontal Plane

+(HP) - refers to perpendicular to Horizontal Plane
References
Burstone CJ (1958) The integumcntal profile. Am] Lcgan H, Burstonc CJ (1980) Soft tissue
Ortbod 44:1-25. cephalometric analysis for orthognathic surgery. ]
Oral Surg 38:744-51.
268
M C N A M A R A A N A L Y S I S (13.14)
Sample
origin Ann Arbor sample age average age females: 26 years, 8 months
size 111 young adults average age males: 30 years, 9 months
race Caucasian clinical characteristics
sex male and female good to excellent facial configurations of
untreated adults with good occlusions
13.14 Effective midfacial and mandibular lengths. Effective

MIXED midfacial length is constructed from point A to condylion. Effective
DENTITION mandibular length is constructed from anatomic gnathion (on the
contour of the symphysis) to condylion (A).
Effective midfacial and mandibular lengths in: (B) ideal female adult;
(C) ideal male adult. The maxillomandibular differential is
CONDYLION determined by subtracting effective midfacial length from effective
mandibular length.
(From McNamara, 1984; reprinted with permission.)
POINT A
ANATOMICAL
GNATHION

269
Variables and norms

Females (n=73) Males (n=38)
Mean SD Mean SD
Maxilla to cranial base

Nasion perpendicular to point A 0.4 2.3 1.1 2.7 (mm)
SNA angle 82.4 3.0 83.9 3.2 (deg)
Mandible to maxilla
Effective length of maxilla
(Condylion to point A) 91 4.3 99.8 6.0 (mm)
Effective length of mandible
(Condylion to gnathion) 120.2 5.3 134.3 6.8 (mm)
Maxillomandibular differential 29.2 3.3 34.5 4.0 (mm)
Lower anterior facial height
(ANS to men ton) 66.7 4.1 74.6 5.0 (mm)
Mandibular plane angle 22.7 4.3 21.3 3.9 (deg)
Facial axis angle 0.2 3.2 0.5 3.5 (deg)
Mandible to cranial base

Pogonion to Na perpendicular -1.8 4.5 -0.3 3.8 :mm
Dentition
Upper incisor to point A vertical 5.4 1.7 5.3 2.0 mm,
Lower incisor to A-Po line 2.7 1.7 2.3 2.1 mm
Airway measurements
Upper pharynx 17.4 3.4 17.4 4.3 mm
Lower pharynx 11.3 3.3 13.5 4.3 mm'
Composite norms
Mixed dentition Change per year Adult
Maxillary skeletal
Nasion perpendicular to point A 0 Minimal 1 (mm)
Maxillary dental
Upper incisor to point A vertical 4-6 No change 4-6 (mm)
Mandibular dental
Lower incisor to A-Po line 1-3 No change 1-3 (mm)
Mandibular skeletal
Pogonion to Na perpendicular -8 to -6 0.5 -2 to +4 (mm)
Vertical measures
Mandibular plane angle 25 -1 every 3-4 yean ; 2 2 (deg)
Facial axis angle 0(90) No change * 0(90) (deg)
References
McNamara JA Jr (1984) A method of McNamara JAJr, Brust EW, Riolo ML (1993) Soft
cephalometric evaluation. Am} Orthod 86:449-69. tissue evaluation of individuals with an ideal
occlusion and a well-balanced face. In: McNamara
McNamara JAJr, Brudon WL (1993) Orthodontic JA Jr (ed) Esthetics and the Treatment of facial
and Orthopedic Treatment in the Mixed Dentition. Form. Monograph 28, Craniofacial Growth Series.
(Needham Press: Ann Arbor.) (University of Michigan, Center for Human Growth
and Development: Ann Arbor.)
270
RICKETTS ANALYSIS (13.15)
13.15 Landmarks used in the Ricketts analysis (A):

A - the deepest point on the curve of the maxilla between the
anterior nasal spine and the dental alveolus
ANS - tip of the anterior nasal spine
BA - most inferior posterior point of the occipital bone
CC - point where the basion—nasion plane and the facial axis
intersect
DC - a point selected in the centre of the neck of the condyle
where the basion-nasion plane crosses it
NA - a point at the anterior limit of the nasofrontal suture
PM - point selected at the anterior border of the symphysis
between Point B and pogonion where the curvature changes from
concave to convex
PO - most anterior point on the midsagittal symphysis tangent to
the facial plane
XI - the geometric centre of the ramus of the mandible.
Variables used in the analysis (B).

(From Ricketts et al, 1979; reprinted with permission.)
271

Mean SD For 9 year old + age adjustment
Chin in space
Facial axis (1) 90 ±3 N o adjustment (deg)
Facial angle depth (2) 87 ±3 Adjust +1 degree every 3 years (deg)
Mandibular plane (3) 26 ±4 Adjust - 1 degree every 3 years (deg)
Facial taper (4) 68 ±3 No adjustment (deg)
Lower facial height (5) 47 *4 No adjustment (deg)
Mandibular arc (6) 26 s4 Mand. arc closes V, degree/year (deg)
Angle increases / 2 degree/year
Convexity
Convexity of point A (7) 2 ±2 Adjust - 1 mm every 3 years iiiim
Teeth
Lower incisor to APo (8) 1 ±2 No adjustment (mm)
Upper molar to PtV (10) Age+3 (mm)
Mandibular incisor inclination (9) 22 ±4 No adjustment (deg)
Profile
Lower lip to E-plane (11) -2 ±2 Less protrusive with growth in m
References
Ricketts RM (1957) Planning treatment on the basis Ricketts RM (1975) A four-step method to
of the facial pattern and an estimate of its growth. distinguish orthodontic changes from normal
Am] Orthod 27:14-37. growth. / Clin Orthod 9:208-28.
Ricketts RM (1960) The influence of orthodontic Ricketts RM, Bench RW, Gugino CF, Hilgers JJ,
treatment on facial growth and development. Angle Schulhof R (1979) Bioprogressive therapy. (Rocky
Orthod 30:103-33. Mountain Orthodontics: Denver) 55-70.
Ricketts RM (1960) A foundation for cephalometric Ricketts RM (1981) Perspectives in the clinical
communication. Am J Orthod 46:330-57. application of cephalometrics. The first five years.
Angle Orthod 51:115-50.
Ricketts RM, Bench RW, Hilgers JJ, Schulhof R
(1972) An overview of computerized cephalo- Ricketts RM (1991) Orthodontics today - a total
metrics. Am J Orthod 61:1-28. perspective. In: Hosl E, Baldauf A (eds) Mechanical
and Biological Basics in Orthodontic Therapy.
(Huthig Buch Verlag: Heidelberg) 249-308.
272
RICKETTS COMPREHENSIVE COMPUTER DESCRIPTION ANALYSIS
not specified
not specified
not specified
the norm values were established from an deviation was based on the curves of
extensive independent study and an distribution; the actual standard
intensive research of the literature in order deviations were based on an arbitration of
to program the consensus of the published the reports in the literature, and the studies
scientific data available. The clinical of successfully treated cases.

Mean Clinical For 8.5-9 years old +
deviation age adjustment
Field I - The denture problem

Molar relation -3 ±3 No adjustment (mm;
Canine relation -2 ±3 No adjustment (mm;
Incisor overjet 2.5 ±2.5 No adjustment (mm;
Incisor overbite 2.5 ±2 No adjustment (mm;
Lower incisor extrusion 1.25 ±2 No adjustment (mm;
Interincisal angle 130 ±6 No adjustment (deg;
Field II - The skeletal (orthopaedic) problem

Convexity of point A 2 ±2 Decreases 0.2 mm per year (mm)
Lower facial height 47 ±4 No adjustment (deg)
Field III - Denture to skeleton

Upper molar position Age +3 [mm)
Mandibular incisor protrusion 1 ±2.3 No adjustment (mm)
Maxillary incisor protrusion 3.5 ±2.3 No adjustment (mm)
Mandibular incisor inclination 22 ±4 No adjustment (deg)
Maxillary incisor inclination 28 ±4 No adjustment (deg)
Occlusal plane to ramus 0 ±3 Decreases 0.5 mm per year (mm)
Occlusal plane inclination 22 ±4 Increases 0.5 deg per year (deg)
Field IV - Aesthetic problem (lip relation)

Lower lip to F,-plane -2 ±2 Decreases 0.2 mm per year (mm)
Upper lip length 24 ±2 No adjustment (mm)
Lip embrasure - occlusal plane -3.5 Increases 0.1 mm per year (mm)
273
Mean Clinical For 8.5-9 years old +

deviation age adjustment
Field V - Craniofacial relation

Facial depth angle 87 ±3 Increases 0.33 deg per year (deg)
Facial axis 90 ±3.5 No adjustment (deg)
Facial taper 68 ±3.5 No adjustment (deg)
Mandibular plane angle 26 ±4.5 Decreases 0.3 deg per year (deg)
Maxillary depth 90 ±3 No adjustment (deg)
Maxillary height 53 ±3 Increases 0.4 deg per year (deg)
Palatal plane 1 ±3.5 No adjustment (deg)
Field VI - Internal structure
Cranial deflection 27 ±3 No adjustment (deg)

Cranial length 55 ±2.5 Should be corrected for size (mm)
Posterior facial height 55 ±3.3 Should be corrected for size (mm)
Ramus position 76 ±3 No adjustment (deg)
Porion location (TMJ) 39 ±2.2 Should be corrected for size (mm)
Mandibular arc 26 ±4 Increases 0.5 deg per year (deg)
Corpus length 65 ±2.7 Increases 1.6 mm per year (mm)
Should be corrected for size
References
Ricketts RM (1970) The sources of computerized Ricketts RM (1972) The value of cephalometrics
cephalometrics. In: Ricketts RM, Bench RW (eds) and computerized technology. Am j Orthod
Manual of Advanced Orthodontics Seminar. 42:179-99.
Ricketts RM, Bench RW, Hilgers JJ, Schulhof R

(1972) An overview of computerized cephalo
metrics. Am ] Orthod 61:1-28.
274
RIEDEL ANALYSIS
Horizontal reference lines

Sella-nasion line
Variables and norms

Adults Children
Mean SD Mean SD
Skeletal
SNA 82.01 ±3.89 80.79 ±3.85 (deg)
SNB 79.97 ±3.69 78.02 ±3.06 (deg)
ANB 2.04 ±1.81 2.77 ±2.33 (deg)
Mandibular plane (SN-GoGn) 31.71 ±5.19 32.27 ±4.67 (deg)
Angle of convexity (N-A-P) 1.62 ±4.78 4.22 ±5.38 (deg)
Dental
Upper incisors to SN (Ul-SN) 103.97 ±5.75 103.54 ±5.02 (deg)
Interincisal angle (Ul-Ll) 130.98 ±9.24 130.40 ±7.24 (deg)
Lower incisors to mandibular plane (Ll-GoGn) 93.09 ±6.78 93.52 ±5.78 (deg)
Lower incisors to occlusal plane (Ll-OP) 69.37 ±6.43 71.79 ±5.16 (deg)
Upper incisors to facial plane (Ul—FP) 5.51 ±3.15 6.35 ±2.67 (mm)
Upper incisors to Frankfort horizontal 111.2 ±5.7 110.0 ±4.9 (deg)
Reference
Riedel RR (1952) The relation of maxillary
structures to cranium in malocclusion and in normal
occlusion. Angle Orihod 22:142-5.
275
S A S S O U N I ANALYSIS (13.16)
13.16 Definition of planes used in Sassouni cephalometric anal/sis.

Mandibulocranial angle - angle formed by che mandibular base plane and the anterior cranial base plane
Palatocranial angle - angle formed by the palatal plane and the anterior cranial base plane
Palatomandibular angle - angle formed by the palatal plane and the mandibular base plane
Occlusopalatal angle - angle formed by the occlusal plane and the palatal plane
Occlusomandibular angle - angle formed by the occlusal plane and the mandibular base plane
Angle M - angle formed by the 6 axis and the occlusal plane
Angle M' - angle formed by the 6 axis and che palatal plane
Angle M" - angle formed by the 6 axis and the anterior cranial base plane
Angle I - angle formed by 1 and the occlusal plane
Angle I' - angle formed by i and the palatal plane
Angle I" - angle formed by I and che ancerior cranial base plane
Angle R - angle formed by the occlusal plane and the ramal plane
Angle i - angle formed by the occlusal plane and the axis of 1
Angle rfl' - angle formed by the occlusal plane and the axis of 6
(From Sassouni, 1955; reprinted with permission.)
276

Anterior cranial base plane or basal plane
In a well-proportioned face, the anterior cranial base
plane, the palatal plane, the occlusal plane, and the
mandibular base plane meet together posteriorly at
the same point O.
Anterior relationships between point O

and the bony profile of a well-proportioned face A circle drawn with point O as centre and
with O-ANS as the radius, passing through
pogonion, the incisal edge of the upper central
incisor, the anterior nasal spine, nasion, and
the frontoethmoid junction.
Posterior relationships in a well-proportioned face A circle drawn with point O as centre. The
posterior wall of sella turcica also passes
through gonion.
Relationship between the angles formed at point O

Mandibulocranial angle unique to each individual face
Palatocranial angle / palatomandibular angle 1/1
Occlusopalatal angle / occlusomandibular angle 1/1 to 1/2
Teeth axis and facial planes. Maxilla

The axis of 6 and I intersect at the level of the bony orbital
contour
Angle iVT equals angle I'+IO
3 axis - 6 axis - palatal plane form a perfect isosceles triangle
Teeth axis and facial planes. Mandible

Angle R equals angle i
Ramal plane - upper incisor axis - occlusal plane form an isosceles triangle
Angle m' equals angle i' + 5
Axis of lower 7 parallel axis lower incisor
Relationship between teeth axes and other planes

Angle I" equals angle M
Angle I equals angle M1
Angle 1 - palatal plane equals angle I
References
Sassouni V (1955) A roentgenographic cephalo- Sassouni V (1969) A classification of skeletal facial
metric analysis of cephalo-facio-dental relationships, types. Am J Orthod 55:109-23.
Am J Orthod 41:735-64.
Sassouni V (1970) The class II syndrome:
Sassouni V (1958) Diagnosis and treatment differential diagnosis and treatment. Angle Orthod
planning via roentgenographic cephalometry. Am} 40:334-41.
Orthod 44:433-63,
277
SCHWARZ ANALYSIS (13.17)

13.17 Cephalometric tracing of the Schwarz analysis.
Mean SD
Dental
Axial inclinations of the teeth to palatal plane:
upper central incisors 70 ±5 (deg)
65 ±5 (in mixed dentition) (deg)
canines 80 ±5 (deg)
first premolar 90 (deg)
molars 90 ±5 (deg)
Axial inclinations of the teeth to mandibular plane:
lower incisors 90 ±5 (deg)
85 ±5 (in mixed dentition) (deg)
canines 90 ±5 (deg)
Interincisal angle 140 ±5 (deg)
Skeletal
S-Ne 68 (mm)
Corpus mandibular 71 (mm)
Mandibular ramus 50 (mm)
Upper jaw length 47.5 (mm)
Height relations:
Upper / lower incisor 2:3
Upper / lower molar 2:3
Height dentition / skeletal nasal third 6:5
SpP^NSe plane 5 (deg)
SpP~Perpendicular from N': J an gle 85 (deg)
Na-NSe 85 (deg)
H plane-NSe parallel
H plane-Perpendicular from N* 90 (deg)
Occl. plane-Perpendicular from N* 75 (deg)
Mandibular plane-Perpendicular from N* 65 (deg)
Base plane angle (SpP-MP) or B angle: 20 ±5 (deg)
278
Mean
Maxillomandibular angle: 90 (deg)

Gonial angle 133 (dcg)
Length relation of the jaws:
N-Se / upper jaw 60:63
Ramus / mandibular corpus 5:7
Upper jaw / mandibular corpus 2:3
Ant / post jaw height 4 : 3 to 3 :2
Soft tissue thickness

Sn-A 12 children mm,
14-16 adults mm]
Upper lip 12 mmi
Lower lip 12 mnV
Chin cushion 10 mnV
Soft tissue at gnathion 6 mm'
References
Schwarz AM (1958) Die Roentgenostatik. (Urban Schwarz AM, Gratzinger F (1966) Removable
und Schwarzenberg: Wien). Orthodontic Appliances. (WB Saunders: Phila
delphia) 33-60.
Schwarz AM (1961) Roentgenostatics. A practical
evaluation of the X-ray headplate. Am J Orthod
47:561-85.
279
STEINER ANALYSIS (13.18)

13.18 Cephalometric tracing of the Steiner analysis. (From
Steiner, 1953; reprinted with permission.)
Sella-nasion line
Average
SNA angle 82 (deg)

SNB angle 80 (deg)
ANB angle 2 (deg)
SND 76-77 (deg)
GoGn-SN angle 32 (deg)
CC-SN angle not specified (deg)
GnGn'-SN angle not specified (deg)
S to E 51 (mm)
5 toL 22 (mm)
Occlusal plane to SN angle 14.5 (deg)
Interincisal angle 130-131 (deg)
1 to NA 4 (mm)
1 to NA angle 22 (deg)
ltoNB 4 (mm)
1 to NB angle 25 (deg)
Po to NB not specified (mm)
1 to GoGn 93 (deg)
£toNA 27 (mm)
6 to NB 23 (mm)
References
Steiner CC (1953) Cephalometrics for you and me. Steiner CC (1960) The use of cephalometrics as
Am ] Orthod 39:729-55. an aid to planning and assessing orthodontic
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Steiner CC (1959) Cephalometrics in clinical 46:721-35.
practice. Angle Orthod 29:8^29.
280
TWEED ANALYSIS (13.19)
size 95
a large majority of the sample was taken were taken from Dr Tweed's older treated
from non-orthodontic cases from cases, none of whom had previously been
individuals who had good balance of examined cephalometrically.
facial outline rather than ideal. A few cases
13.19 Tweed's triangle. (From Tweed,

1954; reprinted with permission.)

Variables and norms

Mean Range Norms used by
Dr Tweed
FMPA - Frankfort mandibular plane angle 24.57 16-35 25 (deg)

1MPA - Incisor mandibular plane angle 86.93 85-95 90 (deg)
FMIA - Frankfort mandibular incisor angle 68.2 60-75 65 (deg)
References
Tweed CH (1946) The Frankfort - mandibular Tweed CH (1954) The Frankfort - mandibular
plane angle in orthodontic diagnosis, classification, incisor angle (FMIA) in orthodontic diagnosis,
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32:175-230. 24:121-69.
Tweed CH (1953) Evolutionary trends in

orthodontics, past, present, and future. Am J
Orthod 39:81-94.
281
W I T S A P P R A I S A L (13.20)
adults
excellent occlusion
13.20 In 'Wits' appraisal, points A O and

BO are the points of contact o f per
pendiculars dropped from points A and B,
respectively, onto occlusal plane. (From
Jacobson, 1976; reprinted with permission.)
Functional occlusal plane
Variables and norms

0 mm in females
-1 mm in males
References
Jacobson A (1975) The 'Wits' appraisal of jaw
Jacobson A (1985) The 'Wits' appraisal. In:
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282
WORMS A N D COWORKERS' ANALYSIS

(13.21)
13.21 Cephalometric variables suggested by Worms and co-

workers (A and B). (From Worms et al, 1976; reprinted with
permission.)
Vffclcal So(l TlSiu* Propnrtloi"
Fraction A nm
«
VTH 2/5 to M
um 1/5 *0 75
DLL 1/5 20 25
ULL 2/5 -0 HI
283
Variables and norms

Mean S.D.
Facial contour angle -11 (deg)

Throat length 57 (mm)
Lip-chin-throat angle 110 (deg)
Lip protrusion:
Upper lip 3.5 ±1.18 (mm)
Lower lip 2.2 ±0.99 (mm)
N-ANS/ANS-MF 45:55
Vertical soft tissue proportions

Fraction mm
Upper facial height 2/5 40 50

Upper lip length 1/5 20 25
Lower lip length 2/5 40 50
Lower facial height 3/5 60 75
Reference
Worms FW, Isaacson RJ, Speidel TM (1976)
Surgical orthodontic treatment planning: profile
analysis and mandibular surgery. Angle Orthod
46:1-25.
284
WYLIE ANALYSIS (13.22)
size not specified

clinical characterise
Class I cases with good facial balance
13.22 Cephalometric analysis of Wylie,

(From Wylie, 1947; reprinted with per
mission.)
17 17 16 52
Mean Fa c
Pattern - F
Standard

Variables and norms

Mean Mean
Males Females
Glenoid fossa to sella 18 17

Sclla to Ptm 18 17
Maxillary length 52 52
Ptm-6 15 16
Mandibular length 103 101
285
origin films drawn from the University of size 57

California collection of cephalometric clinical characteristics
films good subjective rating of facial aesthetics.
?
ilms taken as part of pretreatment
:ecords. No patient who had had previous
irthodontic treatment was included.
Variables and norms

Total Males Females
Condylar angle 122.49 ±0.71 124.98 ±0.65 126.4 ±0.60

Lower border of man dible 67.3 ±0.46 65.92 ±0.46 65.63 ±0.48
Ramus height .54.81 ±0.56 53.54 ±0.46 52.66 ±0.46
Condyle to Frankfort -0.54 ±0.38 -0.54 ±0.28 0.02 ±0.42
Upper face height 50.65 ±0.38 50.08 ±0.32 48.8 ±0.32
Total face height 113.02 ±0.67 114.92 ±0.60 112.93 ±0.65
UFH/TFHxlOO 43.84 ±0.32 43.62 ±0.27 43.24 ±0.35
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Orthodontic Cephalometry

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What is the book about?

What is the book about?

What topics are covered in chapters 10-13?

What topics are covered in chapters 10-13?

ORTHODONTIC

> Formerly Associate Professor and Director

Preface and Acknowledgments 7

1. The Technique of Cephalometric Radiography 9

2. Anatomy, Radiographic Anatomy and Ccphalometric Landmarks

3. Possibilities and Limitations of Various Cephalometric Variables

4. Cephalometric Methods for Assessment of Dentofacial Changes 105

5. Sources of Error in Lateral Cephalometry 125

6. Posteroanterior (Frontal) Cephalometry 141

7. Applications and Limitations of Cephalometry in Diagnosis and

8. Finding Pathology on Cephalometric Radiographs 175

9. Clinical Research Applications of Cephalometry 181

11. Aspects of Digital Computed Radiography with Cephalometric

12. Computerized Cephalometric Systems 231

13. Landmarks, Variables and Norms of Various Numerical

Sam Wcinstein, DDS, MS

Chapter 1 reviews contemporary radiological technical aspects, addresses imporrant considerations

Chapter 2 constitutes a comprehensive and systematic presentation of all anatomical structures of

Chapter 3 provides an exhaustive discussion of the characteristics of the various cephalometric

Chapter 10 reviews the use of cephalometry to evaluate craniocervical angulation, pharyngeal

The Technique of Cephalometric Radiography

INTRODUCTION technique for producing a lateral head film was

1.3 X-ray cephalo­

1.4-1.6 These images show the cephalometric unit designed by

1.6 O p e r a t o r view of split-screen monitor showing lateral and

The development of such special units, especially for TECHNICAL ASPECTS

The cathode is a tungsten filament surrounded by T h e a n o d e is stationary and comprises a small

STEP UP TPANShQRMER 1.9 X - r a y t u b e w i t h basic e l e m e n t s :

i TUNGSTEN FILAMENT TUNGSTEN TARGET*

1.10 Benson line focus principle showing

ACTUAL FOCAL SPOT l I

THE IMAGE RECEPTOR SYSTEM

An image receptor system records the final product

Image quality is a major factor influencing the The processing procedure

FOCAL SPOT FOCAl SPOT ANODE

FOCAL SPOT ANODE

1.12 Radiographic image produced by a divergent beam

1.13 These diagrams illustrate the factors influencing the size of

Motion unsharpness is caused by movement of the FACTORS AFFECTING THE QUALITY OF

Equipment I: Veraview md-Cp (J Morita Corporation) - Model X-102 md-Cp

Equipment 2: Orthoralix SD Ceph (Phillips Electrical Corporation)

Standard exposure automatic dosage control

Equipment 3: Orthophos C D (Siemens Corporation)

Standard exposure automatic dosage control

Table I . I Examples of cephalometric equipment w i t h standard exposure.

Kreiborg S, Dahl E, Prydso U (1977) A unit for

Anatomy, Radiographic Anatomy and Cephalometric

INTRODUCTION process joins with the frontal process of the zygo­

2.3 Cephalometric landmarks related to the

Anatomy (2.4) Radiographic anatomy (2.5)

2.4 Photograph of the parietal bone.

2.5 Radiograph of the parietal bone.

OCCIPITAL B O N E plate (5). The two radio-opaque lines join together

Cephalometric landmarks (2.8) Bo - Bolron point - the highest point in the

2.8 Cephalometric landmarks related to

SPHENOID BONE The pterygomaxillary fissure appears as a radi-

1.3 X-ray cephalo

INTRODUCTION process joins with the frontal process of the zygo

serious consideration - in other words, the short SPECIFIC CONSIDERATIONS OF A

Variable: Stan TV 1.Ceph 2.Ceph 3.Ceph 4.Ceph Diff. Diff.