CA2505283A1 - Adjustable surveyor table and method of use for adjusting dental implant drill guides - Google Patents

Abstract

A novel dental surveyor table features a model-mounting platform mounted to a base so as to be biaxially swivelable relative thereto. A pair of fixed stop members extend above the platform near one end thereof. A further stop member, also extending above the platform, is linearly movable relative to the platform, such that a dental model can be releasably clamped between the stops. Biaxial swivelability is provided by a pair of swivel mechanisms, oriented transversely to each other and disposed between the platform and the base, with means being provided for releasably clamping both swivel mechanisms in desired angular positions. The surveyor table may thus be used to securely position a dental model at a desired angular orientation, thus facilitating precise fabrication of dental prostheses or restorations, or precise angular alignment of implant drilling guides. Preferably, angular scales are provided to facilitate fine adjustment of both swivel mechanisms.

Description

ADJUSTABLE SURVEYOR TABLE AND METHOD OF USE
FOR ADJUSTING DENTAL IMPLANT DRILL GUIDES
FIELD OF THE INVENTION
The present invention relates in general to surveyor tables for use in making dental prostheses. In particular, the invention relates to adjustable surveyor tables and methods for using same to adjust the angular orientation of adjustable drill guide tubes in dental implant drill guide templates.
BACKGROUND OF THE INVENTION
Dental implants are an increasingly popular alternative to dentures for replacing missing teeth. To replace a single missing tooth using the implant procedure, a cylindrical socket (or osteotomy) is bored into the jawbone - the maxilla (upper jawbone) or the mandible (lower jawbone) as the case may be. A post-like metal implant (typically but not necessarily cylindrical, and preferably made of titanium or a titanium alloy) is then inserted into the socket.
The implant typically has external tapping threads so that it can be screwed into the socket.
Following insertion into the socket, the implant becomes integrated into the jawbone structure by a natural process known as osteointegration. Once osteointegration has occurred, a prosthetic tooth may be attached to the implant. To replace two or more adjacent teeth, two or more sockets are drilled into the jawbone to receive metal implants, and then a multiple-tooth prosthesis is attached to the implants.
For an optimally successful implant procedure, the metal implant (or implants) must be securely anchored in the jawbone, and for this reason the axis of the sockets for the implants should be oriented as centrally as possible within the thickness of the jawbone. If a socket is drilled too close to either the inner or outer side of the jawbone, there may not be enough bone material on that side to provide satisfactory structural support for an implant. Ideally, there will be about the same thickness of bone on each side of the socket. To achieve this desirable result, the socket should be started at a point substantially central to the ridge of the mandible or maxilla (as the case may be), and it should be drilled from that point at an appropriate transverse angle to ensure that it stays centrally located as drilling progresses into the bone.
In addition to its lateral or buccal-lingual position (i.e., transverse to the mandibular or maxillar ridge) and transverse angular orientation, an implant socket's longitudinal or mesio-distal position and angular orientation must also be controlled within fairly close tolerances.
Prostheses for dental implants are fabricated for attachment to implants having pre-selected angular orientations, so an implant will assume substantially the same angular orientation as the socket into which it is inserted. Therefore, if an implant socket is drilled at an angle varying more than slightly from the pre-selected angle, the position of implant after insertion into the socket will be offset from the corresponding attachment point of the prosthesis, thus making satisfactory installation of the prosthesis difficult or impossible. It will also be readily appreciated that inaccurate lateral or longitudinal positioning of an implant socket may complicate or preclude satisfactory prosthesis installation.
For all the foregoing reasons, it is important for oral surgeons drilling implant sockets to ensure proper positioning and angular alignment of the sockets. Some surgeons may rely merely on visual observation and judgment to determine socket location and alignment, but this method entails considerable risk. If the surgeon's judgment is inaccurate, or if the surgeon's manipulation of the drill is imprecise, the result may be an unusable socket.
It is preferable, therefore, to use some physical apparatus for guiding the drill bit along a desired path into the jawbone, and the prior art discloses several known apparatus directed to this purpose.
U.S. Patent No. 5,556,278 (Meitner) discloses a method of making a template for guiding a drill bit for drilling an implant socket. The first step is to cast a model of the affected portion of the patient's jaw, using methods and materials well known in the field of dentistry.
The model provides a very accurate three-dimensional representation of the gum surface in the edentulous (i.e., toothless) region intended to receive implants, as well as any teeth adjacent to the edentulous region. One or more holes are drilled into the model in the region corresponding to the edentulous region of the patient's jaw (one hole for each intended implant), with a starting point and angular orientation corresponding to the intended position and orientation of the eventual implant socket. A guide post, typically made of metal and _2_ having an outer diameter corresponding to the diameter of intended implant socket, is inserted into each of the holes. A cylindrical guide tube, having an interior diameter slightly larger than the diameter of the guide post, is placed over the guide post. A template is then formed by applying a molding material (e.g., an acrylic material) around the guide tube (or tubes). When the molding material has dried or set, the template is removed from the model with the guide tubes embedded into it. The template is then inserted into the patient's mouth, whereupon the oral surgeon proceeds to drill the desired implant sockets using the guide tubes in the template (i.e., with the drill bit passing through the tubes).
The Meitner method produces satisfactory results provided that the guide tubes have been properly positioned in the template, but this is dependent on the position and orientation of the holes drilled into the model, which in turn involves an element of judgment and therefore is susceptible to inaccuracy. To confirm that the guide tubes are properly positioned, the Meitner method provides that the guide tubes are made with radiopaque material so that their position and orientation can be checked before the sockets are drilled by means of radiologic or tomographic visualization with the template positioned in the patient's mouth.
The problem with this, however, is that if the guide tubes are found to be unsatisfactorily positioned, there is no way to correct this condition, so the template must be discarded and a new one built. This obviously is inefficient and costly.
For these reasons, it is preferable to use a drill guide template that provides for angular adjustment of the guide tube, and preferably in both the lateral and longitudinal planes. Using such an adjustable template, the guide tube can be set at an initial angular orientation (or trial position), and then later adjusted to correct or improve the angular alignment, without needing to discard the template and build a new one.
U.S. Patent No. 5,800,168 (Cascione et al.) discloses a template with a guide tube that can be adjusted with respect to both lateral position and angular orientation.
A radiopaque guide tube is rotatably mounted inside a first radio-transparent housing which in turn is slidably mounted inside a second radio-transparent housing bonded into an acrylic template. The guide tube is rotatable about an axis generally parallel to the ridge of the jawbone so that its angular orientation transverse to the ridge can be adjusted. The first housing is slidable within the second housing transversely to the ridge of the jawbone, thus allowing for adjustment of the lateral position of the guide tube. The template is placed in the patient's mouth with the guide tube in a provisional or test position, whereupon the guide tube is radiologically visualized to confirm whether the guide tube is satisfactorily aligned with the jawbone. If it is not S satisfactorily aligned, adjustments can be made in the plane transverse to the jawbone ridge, by rotating the tube and sliding the first housing within the second housing to achieve a desired transverse position. The guide tube's position can then be checked by further radiologic visualization. This process can be repeated as many times as necessary until the guide tube is positioned and oriented as desired, whereupon it may be fixed into position within the template by introducing a filler material into the first and second housings. An implant socket may then be drilled into the jawbone, with the drill bit passing through the guide tube in the template.
The Cascione apparatus enhances the oral surgeon's ability to ensure satisfactory positioning and orientation of implant sockets by providing for adjustment of the guide tube, but this adjustability is limited to lateral positioning and angular adjustment about one axis only. Cascione has an additional drawback in that it entails specialized (and thus costly) construction by virtue of the pivoting guide tube and slidable housing assembly.
Another type of adjustable drill guide template is described in Canadian Patent Application No. 2,484,475 filed by Csillag on October 12, 2004 (the "Csillag '475 application"). The Csillag template incorporates a guide tube disposed within a spherical swivel ball that is rotatably retained, in ball-and-socket fashion, within the template. The guide tube projects outward (i.e., away from the jaw) from the swivel ball, through an opening in the template, so that it can be manipulated in "joystick" fashion, to orient the guide tube as desired.
Once the guide tube has been positioned in a desired angular orientation, it can be fixed in position relative to the template by application of a suitable filler material or bonding material.
With each guide tube thus fixed in position, the template may be placed in the patient's mouth over the corresponding portion of the patient's dentition, whereupon a dental drill bit may be inserted through the guide tube to drill the desired implant socket in the jawbone, with confidence that the axis of the resultant socket will substantially coincide with the pre-set angular orientation of the guide tube.

In one embodiment of the Csillag template, the swivel ball is formed into the template material, such as by sandwiching the ball between layers of acrylic material prior to forming the template using vacuum-forming techniques. In other embodiments, the swivel ball is disposed in a swivel ball housing that allows for lateral adjustment of the swivel ball position, in addition to allowing for multi-axial angular adjustment; the swivel ball housing is then formed into the template.
Both the Cascione template and the Csillag template may be used with reliance on the visual judgment of the dental surgeon who is making adjustments to the angular orientation and lateral position of the drill guide tube. However, if the surgeon's judgment is inaccurate, the angular disposition and lateral position of the implant sockets within the patient's jawbone can be of less than optimal in spite of the adjustability of drill guide tube. For this reason, it is advantageous for the surgeon's judgment to be aided by radiographic diagnostic methods to confirm whether the angular orientation of the drill guide tube is satisfactory, and if it is not, to provide an accurate indication of the required angular and lateral adjustments.
Accordingly, with the template positioned on the model of the patient's dentition, the angular orientation of the guide tube may be set in an initial trial position, and temporarily fixed in place relative to the main body of the template using a suitable filler or bonding material. The guide tube is provided with a radiopaque marking (meaning, for purposes of this patent document, a marking made with a material through which electromagnetic waves such as X-rays will not readily pass) or other suitable means that will indicate the guide tube's angular orientation in radiographic images. The template is then placed over the patient's dentition, and radiographic images of the dentition are taken (preferably from multiple angles).
The radiographic images will show both the angular orientation of the guide tube (in its trial position) and the bone structure of the jaw at the implant site. Having regard to the bone structure disclosed in the radiographic images, the optimal angular orientation of the implant socket (and the corresponding optimal angular orientation of the guide tube) may be plotted on the images, whereupon measurements may be taken of any angular offsets (in one or more planes) between the optimal orientation of the implant socket orientation and the actual angular orientation of the guide tube in its trial position.

After the template is removed from the patient's mouth, the filler or bonding material around the guide tube is removed so that the guide tube is free to move relative to the template body. The guide tube is then angularly adjusted in accordance with the angular offsets measured on the radiographic images. When these adjustments have been made, the guide tube is once again fixed in place using a filler or bonding material. If the adjustments have been made with sufficient precision relative to the measured angular offsets, it should be possible to proceed directly to the socket drilling stage, with confidence that the socket will be satisfactorily oriented within the jawbone structure. However, even though the angular offsets may have been measured quite accurately, the adjustment procedure described above still involves a significant element of human judgment as to whether the adjustments made to the guide tube actually correspond, within acceptable tolerances, to the measured angular offsets.
For this reason, and to provide greater confidence regarding the alignment of the guide tube before the socket is drilled, it may be necessary or desirable to take additional radiographic images after the guide tube has been adjusted, to confirm that the adjustments were satisfactory, or to determine what additional adjustments might be warranted. This procedure may be repeated as many times as necessary, in trial-and-error fashion, until the radiographic images confirm that the angular alignment of the guide tube is satisfactory. The implant socket may then be drilled with virtually total confidence that it will be positioned as intended within the j awbone structure.
While this procedure should always provide satisfactory results, it has significant drawbacks. The patient is inconvenienced by the need to attend on two or more occasions for radiographic imaging. The total time required for the implant procedure, in terms of both calendar days and actual hours spent by the professional personnel involved in the various steps, is increased due to the multiple adjustment operations and multiple radiographic imaging operations. The increased professional time required in this procedure (e.g., for dental surgeons, dental technicians, and radiographic technicians) results in corresponding increases in the total cost to the implant patient.
For the foregoing reasons, there is a need for apparatus and methods than enable reliably accurate adjustment of adjustable dental implant drill guide templates without the need for multiple guide tube adjustment operations and multiple radiographic imaging operations, thus reducing the overall time and cost of the dental implant procedure. The present invention is directed to these needs.
BRIEF SUMMARY OF THE INVENTION
In general terms, the present invention is an adjustable surveyor table for making angular adjustments to an adjustable drill guide tube in a dental implant drill guide template, as well as a method of using the adjustable surveyor table for that purpose.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described with reference to the accompanying figures, in which numerical references denote like parts, and in which:
FIGURE 1 is a perspective view of a dental implant drill guide template having multi-axially rotatable swivel balls with drill guide tubes at sites intended to receive dental implants.
FIGURE 2 is a cross-section through one of the swivel ball and guide tube assemblies of the prior art template shown in Figure 1.
FIGURES 3 and 4 illustrate dental implant drill guide templates with laterally-adjustable mufti-axially rotatable swivel balls.
FIGURE 5 is a perspective view of a dental implant drill guide template and associated marker plug, with swivel ball and guide tube assembly positioned in correspondence with an implant site in an edentulous region of a patient's jaw.
FIGURE SA is a cross-section through the swivel ball and guide tube of the template shown in Figure S.
FIGURE 5B is a side view of the marker plug shown in Figure 5.

FIGURE 6 is a top view of the template of Figure 5, mounted on a corresponding dental model, with a marker plug inserted into and projecting from the guide tube.
FIGURES 7A and 7B are lateral perspective views of the template mounted on the dental model as in Figure 6, illustrating how the marker plug may be multi-axially manipulated to dispose the guide tube in different angular orientations.
FIGURE 8 is a perspective view of a prior art surveyor table for use in fabricating dental prosthetic appliances.
FIGURE 9 is a perspective view of an improved surveyor table in accordance with a first embodiment of the apparatus of the present invention.
FIGURE 9A is a side view detail of an upper swivel bracket of the surveyor table shown in Figure 9.
FIGURE 10 is a perspective view of the dental implant drill guide template and model from Figure 6 mounted on the surveyor table of Figure 9 which in turn rests on the base of a prior art dental surveyor.
FIGURE 11 is a representation of a radiographic side view image of a portion of a dental patient's upper jawbone structure, taken with a drill guide template as in Figure 5 in place over the patient's upper dentition, with a marker plug inserted in the guide tube and oriented in a trial position.
FIGURE 12 is a representation of a radiographic cross-sectional image of the upper jawbone structure and drill guide template depicted in Figure 11.
FIGURE 13 is a perspective view of an improved surveyor table in accordance with a second embodiment of the apparatus of the present invention.
_g_ DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The apparatus and method of the invention are perhaps best understood by first reviewing various types of dental implant drill guide templates that have multi-axially adjustable guide tubes.
Figure 1 illustrates a dental implant drill guide apparatus, generally designated by reference numeral 10, in accordance with the Csillag '475 application. In Figure 1, the apparatus 10 is shown in position on a cast model 70 of a portion of a dental patient's lower dentition, including all existing teeth 72 and an edentulous area in which it is intended to drill a socket to receive one or more implants for anchoring a dental prosthesis to replace one or more missing teeth. The template 20A is made from a radio-transparent material (meaning, for purposes of this patent specification, a material through which electromagnetic waves such as X-rays will readily pass), preferably an acrylic material. At least one substantially spherical swivel ball 30 is rotatably retained in or by the template as conceptually illustrated in Figure 2.
The swivel ball 30 is also made from a radio-transparent material. In the preferred embodiment, the swivel ball 30 is made from an acrylic material.
The swivel ball 30 is rotatably retained in or by the template, in such fashion that the swivel ball 30 can rotate about multiple axes, in the same general way as a ball-and-socket joint. As illustrated in Figure 2, the rotatable retention of the swivel ball 30 by the template 20A is achieved by making the template 20A template from inner and outer layers 22, 24 of radio-transparent material, preferably an acrylic material, and preferably using vacuum-forming techniques that are well known in the art. In a template 20A formed using such techniques, the swivel ball 30 is sandwiched between the inner and outer layers 22, 24 of the template 20A, as shown in Figure 2, with the inner and outer layers 22, 24 of the template 20A
being deformed so as to create a cavity that at least partially conforms to the spherical shape of the swivel ball 30, effectively forming a "socket" in which the swivel ball 30 can rotate. As described in the Csillag '475 application, vacuum-forming techniques can be effectively used to encapsulate an acrylic swivel ball 30 in an acrylic template 20A without creating a bond between the swivel ball 30 and the template 20A, such that rotation of the swivel ball 30 is readily possible.
However, improved rotatability of the swivel ball 30 may be achieved by applying a bond breaking or lubricating material (compatible with the materials of the template 20A and the swivel ball 30) to the interface between the template 20A and the swivel ball 30 during the template fabrication process.
Disposed within the swivel ball 30 is a cylindrical guide tube 40, for receiving a drill bit. The guide tube 40 preferably projects from the swivel ball 30 so as to project through a guide tube opening 26 in the outer surface 23 of the template 20A. At least one dimension of the guide tube opening 26 is larger than the width of the guide tube 40, so as to permit rotation of the swivel ball 30 about at least one axis. In the preferred embodiment, however, the guide tube opening 26 is wider than the guide tube 40 in all directions (and is preferably a substantially circular opening), thus permitting rotation of the swivel ball 30 about multiples axes.
To facilitate rotation of the swivel ball 30, the guide tube 40 may be provided with a 1 S handle 44 as conceptually illustrated in Figure 2. The handle 44 may be of any configuration that permits manipulation of the guide tube 40 and swivel ball 30.
Alternatively (or in addition to handle 44), the guide tube 40 may be fashioned with a tool slot 42 as conceptually illustrated in Figure 2. The tool slot 42 is adapted to receive a tool for manipulating the guide tube 40 and swivel ball 30 into a desired angular orientation.
Figures 3 and 4 illustrate alternative embodiments of the template from the Csillag '475 application, which make it possible to adjust the linear position of the guide tube 40 in the sagittal plane (i.e., mesio-distally) and/or cross-sectional plane (i.e., bucco-lingually).
An elongate swivel ball housing 50 (60) is retainingly disposed within template 20B (20C) which has a guide tube opening 26. The swivel ball housing 50 (60) has a central chamber enclosed by two opposing sidewalls, each of which has an inner face defining a concave, partially-cylindrical groove 52 (63) running substantially the length of the sidewall. The grooves 52 (63) are substantially parallel, and the radius of each groove 52 (63) corresponds to the radius of a swivel ball 30 as previously described. The swivel ball housing 50 (60) also defines a guide tube opening 51 (61) into the central chamber, and the swivel ball housing 50 (60) is positioned in the template 20B such that guide tube opening 51 (61) is generally aligned with the guide tube opening 26 of the template 20B (20C). This construction of the drill guide apparatus 10 allows a swivel ball 30 to be disposed in the central chamber with its guide tube 40 projecting through guide tube openings 26 and 51 (61), with the swivel ball 30 being laterally movable within grooves S2 (63) while also being mufti-axially rotatable.
Figure 5 illustrates a dental implant drill guide template 110 having a round guide tube 140 disposed within a swivel ball 130, with the inner diameter of the guide tube 140 being considerably larger than that of the guide tubes 40 illustrated in Figures 1-4. As best seen in Figure SA, another difference from the embodiments shown in Figures 1-4 is that the guide tube 140 of template 110 does not project beyond the swivel ball 130. The guide tube 140 is adapted to receive a marker plug 120, which comprises a round plug body 122 having a diameter very slightly smaller than the inner diameter of guide tube 140, such that plug body 122 can slide easily into guide tube 140 easily but with virtually no "play".
Plug 120 has inner end 122a disposed toward the jawbone, and outer end 122b disposed away from the jawbone.
Guide tube 140 extends through the lower surface of template 110 such that inner end 122a of plug body 122 will come into contact with the surface of the patient's gum tissue when marker plug 120 is inserted into guide tube 140 when template 110 is positioned over the patient's dentition. For reasons that will become apparent, plug body 122 is configured such that outer end 122b of plug body 122 will not extend beyond the outer edge of guide tube 140 when inner end 122a is in contact with the patient's gum tissue.
Marker plug 120 also comprises a marker stem 124 extending from outer end 122a or plug body 122 and, in the preferred embodiment shown in Figure SB, a marker button 126 extending from inner end 122a. Marker stem 124 is preferably oriented in substantially coaxial alignment with the plug body 122. Guide tube 140, marker stem 124, and marker button 126 are all made of a radiopaque material (e.g., steel). Plug body 122 may be made, but need not necessarily need to be made, of a radiopaque material. In the preferred embodiment, all components of marker plug 120 are made of the same radiopaque material for ease of fabrication.

Figures 6, 7A, and 7B illustrate template 110 in place on dental model 70, with the swivel ball 130, guide tube 140, and marker plug 120 assembly disposed in an area analogous to an edentulous portion of the patient's dentition. Figures 7A and 7B are essentially identical except that they illustrate two of the many different orientations into which the marker stem 124 (and, therefore, the marker plug 120, guide tube 140, and swivel ball 130) may be manipulated.
Figure 8 illustrates a prior art dental surveyor table 80. As used in this document, the term "surveyor table" refers to apparatus on which a dental model may be mounted and positioned in different angular orientations, to facilitate fabrication of dental prosthesis. Prior art surveyor table 80 has a base 82 and a model-mounting platform 84. Platform 84 has an movable stop 90 slidably disposed within a guide track in platform 84, and two or more fixed stops 92. The position of movable stop 90 is adjusted by means of an adjustment knob 94, which rotates a threaded rod 96 which engages a threaded bore in movable post 90. Platform 84 is mounted to base 82 by means of a swivel joint 86, such as a ball-and-socket joint as shown in Figure 8. The orientation of platform 84 relative base 82 is thus mufti-axially adjustable, and platform 84 can be releasably locked in position by means of clamping knob 88.
However, prior art surveyor table 80 does not provide any means for gauging or precisely setting the angulax orientation of platform 84.
Figure 9 illustrates an improved dental surveyor table 200 in accordance with the present invention. In the embodiment shown in Figure 9, surveyor table 200 has a base 202, a model-mounting platform 220 (with upper surface 221), movable stop 222 (slidably movable in guide track 226), fixed stops 224, and adjustment knob 228 generally similar to the analogous components of the prior art surveyor table 80 shown in Figure 8. Platform 220 is mounted to a first swivel mount body 240 such that platform 220 can swivel about a first axis X, which typically and preferably will be substantially parallel to upper surface 221 of platform 220.
First clamping means are provided for releasably clamping platform 220 in different orientations relative to selected orientations by means relative to first swivel mount body 240.
It will be readily apparent to persons skilled in the field of the invention that there will be numerous ways in which platform 220 may be pivotably mounted to first swivel mount body 240, and numerous forms which first clamping means may take, using well-known principles and techniques of machine design and fabrication, and the present invention is not intended to be limited by any particular means of incorporating these functional features into the apparatus.
For exemplary purposes, however, as illustrated in Figures 9 and 9A, platform 220 may be fashioned with a pair of downwardly-extending upper swivel brackets 230, each defining an opening 232 for receiving a trunnion or axle means (not shown) about which platform 220 may pivot about first axis X. One of the upper swivel brackets 230 has a discontinuous end 234 adjacent platform 220, such that it may be clamped about the trunnion or axle means by applying a force F against discontinuous end 234 such that discontinuous end 234 elastically deflects toward the trunnion or axle means and is urged into contact therewith, thus preventing rotation of platform 220 around first axis X. In the embodiment shown in Figure 9, this is accomplished by means of a first clamp knob 248 attached to a first threaded rod 249 which passes through a threaded bracket (not shown), such that rotation of first clamp knob 248 in a first direction will exert force F against discontinuous end 234 of upper swivel bracket 230, thus clamping upper swivel bracket 230 around the trunnion or axle means as described above.
Pivotability is easily restored by turning first clamp knob 248 in the other direction.
The surveyor table 200 includes first angular gauge means, for measuring the rotation of platform 220 about first axis X. In the embodiment shown in Figure 9, the first angular gauge means is provided in the form of first dial 242, which has first angular scale 246. First dial 242 may be provided with a first dial knob 244 to facilitate rotation of first dial 242. A first reference mark 228 is provided on or in association with platform 220. First dial 242 is rotatable independently of other components, and will not rotate relative to first swivel mount body 240 when platform 220 is rotated about first axis X.
With platform 220 oriented in a first selected position, a user may turn first dial 242 so as to align first reference mark 228 with a selected mark on first angular scale 246, and then pivot platform 220 to a desired second position, whereupon the angle through which surveyor table 200 has been pivoted about first axis X can be easily and accurately determined by reading the new position of first reference mark 228 on first angular scale 246. Similarly, when it is desired to rotate platform 220 through a specific angular displacement about first axis X, the user simply notes the position of first reference mark 228 with respect to first angular scale 246, determines what final position of first reference mark 228 when platform 220 has been rotated the desired amount, and then rotates surveyor table 200 until first reference mark 228 is at the predetermined final position with respect to first angular scale 246.
First swivel mount body 240 is pivotably mounted to a second swivel mount body 250, such that first swivel mount body 240 and, therefore, platform 220 can swivel about a second axis Y, which typically and preferably will be substantially horizontal (i.e., substantially parallel to the underside of base 202), and will also be substantially perpendicular to first axis X when viewed from above. Second swivel mount body 250 is non-rotatably mounted to base 202. Second clamping means are provided for releasably clamping first swivel mount body 240 in different orientations relative to second swivel mount body 250. In the embodiment shown in Figure 9, the second clamping means comprises second clamp knob 258 and second threaded rod 259 which are functionally similar to first clamp knob 248 and first threaded rod 249 respectively. However, persons skilled in the art will appreciate that the second clamping means may be provided in various other forms using known principles and techniques.
The surveyor table 200 includes a second angular gauge means, for measuring the rotation of second swivel mount body 250 (and platform 220 as well) about second axis Y. In the embodiment shown in Figure 9, the second angular gauge means is provided in the form of a second dial 252, with second angular scale 256 and second dial knob 254 to facilitate rotation of first dial 242. A second reference mark 249 is provided on or in association with first swivel mount body 240. Second dial 252 is rotatable independently of other components, and will not rotate relative to second swivel mount body 250 when first swivel mount body 240 is rotated about second axis Y.
Figure 10 illustrates surveyor table 200 positioned on a prior art dental surveyor 150.
Dental surveyor 150 has a base 152, a vertical mast 154, and an arm 156 which is mounted to mast 154 by means of swivel mount 158 such that it can swivel about the vertical axis of mast 154. A rod housing 160 is attached to the end of arm 156. A rod 170 extends vertically through a vertical passage (not shown) in rod housing 160, and a chuck 174 is fitted to the lower end of rod 170 which projects below rod housing 160. A helical spring 172 is disposed around rod 170 as shown, and is retained on rod 170 by a rod cap 174 connected to the upper end of rod 170. Rod 170 is vertically slidable through rod housing 160, with spring 172 biasing rod 170 toward an uppermost position. However, rod 170 may be clamped in a desired position by turning clamp knob 162 attached to a threaded rod (not shown) which passes through a threaded hole (not shown) in rod housing 160 and presses against rod 170 so as to prevent vertical movement of rod 170.
In the arrangement illustrated in Figure 10, dental model 70 (with drill guide template 110 in place thereon, and with marker plug 120 and guide tube 140 in a trial position) has been clamped in place on platform 220 of surveyor table 200, and a sleeve 176 is fitted to chuck 174.
Sleeve 176 has a cylindrical bore having a diameter very slightly smaller than the diameter of marker stem 124, such that marker stem 124 can slide easily over marker stem 124 but with virtually no "play".
An understanding of the method of the present invention will be enhanced by referring to Figures 11 and 12, which are representations of radiographic images of a dental patient's upper jaw, taken with drill guide template 110 in place over the patient's dentition, and with marker plug 120 inserted into guide tube 140. Figure 11 is a lateral image of the jawbone 180, with sinuses (or other bone discontinuities in the jaw structure) 182, existing teeth 184, and roots 186. The surface of tissue covering jawbone 180 (i.e., the gum line) is denoted by reference numeral 188. Figure 12 is an image looking along the ridge of jawbone 180 (per section line 12-12 in Figure 11). Being made of a radio-transparent material, template 110 and swivel ball 130 are not seen in the radiographic images. However, marker stem 124 and guide tube 140 are visible as images 124' and 140' respectively.
Image 124' of marker stem 124 allows a technician to make an accurate determination of the line along which a dental implant socket would be oriented if drilled using template 110 with guide tube 140 in the trial position shown in the radiographic images. At the same time, the technician can determine whether it is desirable or necessary to select a different alignment for the socket, such as to optimize the depth of the socket within bane 180 or to avoid the socket coming too close to a lateral edge of the ridge of bone 180. As conceptually illustrated in Figure 11, the trial position of guide tube 140 in one plane (indicated by line L1-A) is fairly good, and the technician has determined that only a small angular adjustment (through angle 8) is required to bring the socket line into optimal alignment (along line L1-B).
In contrast, a comparatively large angular adjustment (through angle ~ ) is needed in the transverse plane, to move the transverse socket line from the trial position (along line L2-A) to the optimal position (along line L2-B).
S With this information from the radiographic images, the technician is now ready to make a precise adjustment of the guide tube 140 using the improved surveyor table 200 of the present invention, in conjunction with a dental surveyor 150 as illustrated in Figure 10. As an initial step, it is important to ensure that guide tube 140 has been temporarily but securely bonded in place (relative to template 110) in the trial position corresponding to the radiographic images taken with template 110 positioned over the patient's dentition. It is also desirable -- to optimize the accuracy of the adjustment of the guide tube 140 -- to ensure that model 70 is positioned such that the jawbone ridge of model 70 in the vicinity of the implant site (or a line tangential to the ridge in the vicinity of the implant site) is substantially parallel to either first axis X or second axis Y. Platform 220 of surveyor table 200 may then be manipulated such that sleeve 176 slides over marker stem 124, whereupon platform 220 is clamped in position using the first and second clamping means of surveyor table 200.
Sleeve 176 may now be withdrawn from marker stem 124, and, if desired, surveyor table 220 (with model 70 still clamped in place on platform 220) may be moved away from surveyor 150. First dial 242 is then zeroed (or otherwise correlated) relative to first reference mark 228, and second dial 252 is zeroed (or otherwise correlated) relative to second reference mark 249. First clamp means may then be released so that platform 220 can be rotated about first axis X through angle B (or angle ~ , as appropriate, depending on the orientation of model 70), having reference to first angular scale 246, whereupon the first clamp means is re-tightened. Next, the second claim means is released so that platform 220 can be rotated about first axis X through angle fi (or angle B, as appropriate), having reference to second angular scale 256, whereupon the second clamp means is re-tightened. (Persons skilled in the art will readily grasp that the order of these steps may be reversed without departing from the invention.) The bond between guide tube 140 and template 110 is then broken so that guide tube 140 is now free to rotate within template 110 (alternatively, this step may be taken prior to the angular adjustments of platform 220 described above). Surveyor table 200 (with model 70 still clamped in place on platform 220) is then re-positioned (if necessary) upon base 152 of surveyor 150. Marker stem 124 is then manipulated so as to be vertically oriented, or nearly so, such that sleeve 176 can be slid over marker stem 124. Because guide tube 140 is at this stage free to rotate within template 110, the positioning of sleeve 176 over marker stem 124 will cause marker stem 124 to be moved into substantially true vertical alignment (corresponding to the vertical alignment of sleeve 176). Because of the biaxial angular adjustments made to platform 220 (i.e., through angles 8 and 4i determined from the radiographic images), the positioning of marker stem 124 into true vertical alignment has the effect of making the corresponding angular adjustments to the orientation of guide tube 140 relative to template 110.
With marker stem 124 still disposed within sleeve 176, the next step in the method is to re-bond guide tube 140 securely to template 110, whereupon sleeve 176 may be withdrawn from marker stem 124, and template 110 may be removed from model 70.
By means of the steps described above, template 110 has been adjusted such that the axis of guide tube 140 closely coincides with the optimal orientation of the intended dental implant socket as represented by lines L1-B and L2-B from Figures 11 and 12.
Template 110 is now ready for immediate placement over the patient's actual dentition, and for immediate use to guide the oral surgeon in drilling the desired implant socket, with confidence that the orientation of the socket in the patient's jawbone will closely coincide with the predetermined optimal orientation. In fact, the inventor's experience has been that the orientation of the implant socket can be adjusted within a precision of as little as 0.1 degrees in any direction, using the method described above.
The method of the invention may include additional steps whereby the optimal depth of the implant socket may be determined with precision. In cases where an implant socket is to be drilled in a region of the patient's jawbone near a sinus cavity 182 (or other bone discontinuity), as in the case conceptually illustrated in Figures 1 l and 12, it is important to ensure that the socket is drilled to an optimal depth without penetrating the sinus cavity 182.
As previously described, outer end 122b of plug body 122 preferably will not extend beyond the outer edge of guide tube 140 when inner end 122a of plug body 122 is in contact with the patient's gum tissue. Therefore, the distance from the outer edge of guide tube 140 to the gum tissue surface 188 will be equal to the length of guide tube 140 if the inner end 122a of plug body 122 substantially coincides with the inner end of guide tube 140 (i.e., if the inner end of guide tube 140 also is in contact with gum tissue surface 188).
In the preferred embodiment of marker plug 120, as shown in Figure 5B, plug body 122 has marker button 126 projecting from inner end 122a. Marker button 126 will contact gum tissue surface 188 when marker plug is inserted into guide tube 140.
Therefore, marker button 126 will facilitate more accurate determination of the location of gum tissue surface 188 in radiographic images in a case where the inner end of guide tube 140 does not coincide with gum tissue surface 188. In that case, the distance from the outer edge of guide tube 140 to the gum tissue surface 188 can be measured on the radiographic images as the distance from the outer end of guide tube 140' to the inner end of marker button 126. The thickness T of the gum tissue can also be readily measured from the radiographic images, by measuring from the inner end of guide tube image 140' (or marker button image 126') to the surface of bone 180 along the selected implant socket line.
With the foregoing information at hand, the oral surgeon can determine the optimal depth to which the implant socket is to be drilled into the bone, and can drill the socket to the selected depth using the outer end of guide tube 140 as a reference datum, since the distance to the bone surface relative to guide tube 140 has been determined with precision.
Drilling of the implant socket then proceeds in accordance with normal and appropriate methods. This may involve the use of one or more drilling sleeves (not shown), each having an outer diameter very slightly smaller than the inner diameter of guide tube 140, but with different inner diameters corresponding to different drill bits or burs that the oral surgeon has elected to use. The implant socket is formed by first drilling a small-diameter pilot hole into the bone using one drill sleeve, and then enlarging this pilot hole using a one or more larger-diameter burs and corresponding drill sleeves. The final enlargement will typically be made through guide tube 140, using a bur of corresponding size.

Persons skilled in the art will appreciate that the present method does not require the use of a drill guide template the same as or largely similar to template 110, with guide tube 140 wholly disposed within swivel ball 130, and adapted for use with marker plug 120. The method is also readily adaptable for use with other drill guide templates having mufti-axially adjustable guide tubes, in accordance with the general principles of the method. For example, the templates shown in Figures 1-4 may be adjusted largely as described above, with minor modification to the method steps. In one particular modification, a round pin could be fitted to chuck 174 of surveyor 150, for insertion into the bore of guide tube 40 (or 140). Alternatively, guide tube 40 could be made to extend further out of swivel ball 30 than shown in Figures 1-4, so as to facilitate positive engagement with sleeve 176 (the inner diameter of which would be correspondingly adjusted).
Persons skilled in the art will also appreciate that various modifications may be made to the apparatus of the present invention without departing from the concept and scope of the invention. To provide only one example, a particularly preferred embodiment of the apparatus is illustrated in Figure 13. In this embodiment, surveyor table 210 is generally similar to surveyor table 200, with all components below the platform 260 being essentially the same (and marked with the same reference numerals). However, surveyor table 210 has a turntable 270 mounted to platform 260 so as to be rotatable about an axis substantially perpendicular to the surface of platform 260 as indicated by the curved arrows in Figure 13.
Turntable 270 may be clamped to platform 260 in a selected rotational position by means of clamp screw 276.
In the preferred embodiment, turntable 270 is laterally movable in one or preferably two directions, so that the position of a dental model mounted on turntable 270 can be laterally adjusted relative to axes X and Y. This desirable feature can be provided by various alternative means. For example, in the embodiment illustrated in Figure 13, platform 260 is laterally movable in a direction parallel to axis X relative to first swivel mount body 240 by means of rack-and-pinion gearing (not shown) controlled by control knob 278. The lateral position of turntable 270 (and, therefore, the position of a model placed thereon) will be transversely adjustable relative to axis Y. Persons skilled in the art will readily appreciate that a similar gearing arrangement or other suitable mechanism can be incorporated into the apparatus to provide for lateral adjustability relative to axis X (for example, by interposing a second rack-and-pinion gear arrangement between platform 260 and first swivel mount body 240, facilitating lateral movement of platform 260 in a direction parallel to axis Y). In another alternative construction, single or dual lateral movement mechanisms may be disposed between turntable 270 and platform 260, such that the position of turntable 270 is laterally adjustable relative to platform 260 and, in turn, relative to axes X and Y.
The rotatability and lateral adjustability of turntable 270 facilitates optimal orientation of a dental model with respect to first axis X and second axis Y, so as to enhance the accuracy of angular adjustments to the guide tubes of an implant drill guide template mounted on the model. For optimal accuracy, it is desirable for such angular adjustments to be made with the implant site on the model positioned directly over the intersection of axes X
and Y, and this is easily achieved with turntable 270.
As shown in Figure 13, turntable 270 does not have movable and fixed stops for clamping a dental model as in the embodiment of Figure 9 (although that modification would be possible in an alternative embodiment). Instead, turntable 270 a plurality of grooves 272 configured for mating engagement with corresponding projections on the underside of the model, in accordance with known methods of casting dental models. A magnet 274 embedded near the center of platform 260 will magnetically interact with a ferromagnetic insert in the bottom of the model, so as to hold the model securely in place (also in accordance with known techniques). Persons skilled in the art will appreciate that platform 220 of the embodiment shown in Figure 9 could also be modified to eliminate the movable and fixed stops and to incorporate grooves 272 and magnet 274 as in Figure 13.
Surveyor table 210 also features alignment guide 280, for assisting the eye in aligning a dental model with axes X and Y, and in positioning the implant site of the model relative to the intersection of axes X and Y. In the embodiment shown in Figure 13, alignment guide 280 comprises a lateral arm 282 connected to a vertical mast 284, which is vertically adjustable by means of rack-and-pinion gearing (schematically not shown) disposed within mast housing 290 and controllable by height control knob 292. Alignment guide 280 is also laterally adjustable by means of rack-and-pinion gearing 294 (generally indicated by reference numeral 294) and controllable by lateral adjustment knob 296 associated with platform 260.
Preferably, alignment guide 280 can be fully retracted from platform 260.
In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following that word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element.

Claims (2)

1. A dental surveyor table comprising:
(a) a model-mounting platform;
(b) two or more fixed stops connected to and projecting above the platform;
(c) a movable stop associated with the platform, and operable to releasably clamp an object between the fixed stops and the movable stop;
(d) a first swivel assembly having a first axis, and being disposed below the platform and swivelably mounted thereto such that the platform can swivel about the first axis;
(e) a second swivel assembly having a second axis transverse to said first axis, said second swivel assembly being disposed below the first swivel assembly and swivelably mounted thereto such that the first swivel assembly can swivel about the second axis;
(f) a base underlying, and rigidly connected to, the second swivel assembly;
and (g) adjustment means for:
g.1 adjusting the position of the movable stop relative to the fixed stops;
g.2 adjusting and releasably locking the angular position of the platform; and g.3 adjusting and releasably locking the angular position of the first swivel assembly.

2. The surveyor table of Claim 1, further comprising angular scales associated with the first and second swivel assemblies.