US2713720A - Orthodontic appliance - Google Patents

Description

y 1955 F. w. JOHNSON 3,

ORTHODONTIC APPLIANCE Filed May 31, 1952 IN VEN TOR. FRANK W. JOHNSON A T TORNE V United States Patent ORTHODGNTIC APPLIANCE Frank W. Johnson, Duarte, Qalifi, assignor to Unitek Corporation, Pasadena, Calif., a corporation of California Application May 31, 1952, Serial No. 291,050

9 Claims. (CI. 32-14) This invention relates to a bracket for orthodontia of the type adapted to attachment to a tooth band. The invention further relates to a method of fabricating such brackets.

Heretofore this type of bracket has generally been formed from flat metal strips with the arch wire receiving groove, the two lateral ligature wire receiving grooves and the base flange being formed by separate broaching or milling operations. Brackets produced by such prior techniques are flat and are often fabricated and sold as integral multiple bracket flat strips. Such strips may be scored at spaced intervals to facilitate severance of individual brackets.

I have now developed an improved bracket characterized by a generally arcuate configuration in which, as preferred practice, the inner and outer surfaces of the bracket together with the several wire receiving grooves are formed on coaxial radii. In one aspect, therefore, the invention contemplates an orthodontic bracket comprising a relatively thin arcuate base, an integrally formed projection extending from the convex face of the arcuate base, the projection having an arch wire receiving groove in its outer face lying parallel to the longitudinal axis of the base and extending from end to end of the projection, and overhanging lips extending along opposite side edges of the projection outwardly of the lateral edges of the base to form ligature wire receiving channels along the bracket edges. In a preferred embodiment, the outer face of the projection, the bottom of the arch wire receiving groove and the bottom of the ligature wire receiving channels are curvilinear in the direction of the longitudinal axis of the base substantially paralleling the curvature of the base.

The bracket as above described represents an improvement over presently conventional flat brackets in that the configuration of the base flange approximates the contours of tooth surfaces and thereby facilitates placement. To further achieve this desirable objective, the base flange may be shaped arcuately along both its longitudinal and transverse axes, as hereinafter described. In addition, the curvilinear arch wire receiving groove in the preferred form of the invention provides a relatively greater contact surface for engagement with the arch wire with a consequent increased stability and comfort.

An important feature of the invention is the method of fabricating the improved bracket, which not only results in the improved arcuate configuration but in addition is appreciably less expensive than the operations required to produce conventional flat brackets.

The method involves forming a plurality of integrally connected brackets in a closed ring by machining the ring on a conventional turning machine such as a lathe, screw machine or the like, whereby one or more of the bracket surfaces are developed on coaxial radii in a series of turning operations which may be carried out for the most part without removing the stock from the machine.

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In another aspect, therefore, and in accordance with presently preferred practice, the invention contemplates the method of forming orthodontic brackets having a base flange and an integral projection extending therefrom providing an arch wire receiving groove and ligature wire receiving channels which comprises forming a plurality of such brackets in an integral ring with the outer face of the projection, the flange, arch wire receiving groove, and ligature wire receiving channels formed on coaxial radii. More particularly, the method comprises forming a plurality of such brackets in an integral ring from a metal stock in the following steps:

(1) Developing an inside diameter to form the inner face of the base flange, this step being unnecessary if a tubular stock of appropriate I. D. is employed;

(2) Developing an outside diameter to form the outer face of the projection, this step being unnecessary if tubular stock of appropriate 0. D. is employed;

(3) Cutting an annular groove in the outer circumference;

(4) Shaping the lateral edges of the ring on equal radii about axes transverse to the axis of the ring;

(5) Undercutting each of the shaped lateral side edges to form channels outwardly of the lateral side edges of the inside face of the ring;

(6) Cutting the ring from the stock at the extremity of the adjoining curved lateral edge;

(7) Grooving the outer circumference of the ring transversely at spaced intervals and to a depth exceeding that of the annular groove to form the upper face of the base flange between adjacent integral remaining projections; and

(8) Severing the ring into sections to form a rality of bracket members.

These several steps may be carried out in any desired sequence depending upon such factors as available machine time, production requirements and the like. A part or all of the several forming operations may be carried out after the cut off operation by re-chucking the cut-off ring. At the present time the partially formed ring is re-chucked during fabrication in the production of these brackets.

The invention will be more clearly understood by reference to the following detailed description taken in relation to the accompanying drawing, in which:

Fig. 1 is a plan view of a bracket in accordance with the invention;

Fig. 2 is a longitudinal section taken on the line 2-2 of Fig. 1;

Fig. 3 is a transverse section taken on the line 33 of Fig. 2;

Fig. 4 is an elevation, partly in section, showing a plurality of the brackets in integral ring form; and

Fig. 5 is a transverse section through an alternative form of bracket.

Referring to Figs. 1, 2 and 3 of the drawing, the bracket is shown in Fig. l at approximately ten times actual size and in Figs. 2 and 3 at approximately twenty times actual size. Obviously the bracket may be made in any size and normal commercial production involves size differentials of or more so that the size comparisons with respect to the drawing are only approximate and are extending from one or both ends of the projection. As illustrated in Figs. I, 2 and 3, the base projects approximately equidistant from opposite ends of the projection 12, but, as will become apparent in relation to the description of the integral bracket ring of Fig. 4, one of the advantages of the invention isthe ease with which different arrangements may be produced if desired. For example, a bracket including two projections with an intervening connecting base flange may be formed for special purposes.

The upper surface of the projection 12 is preferabiy curved, as illustrated, in the direction of the longitudinal axis of the base and coaxially with the under surface of the base. The bracket is provided with a longitudinally extending arch wire receiving groove 14, the bottom surface 14A of which, in the preferred embodiment, is like wise curved in the direction of the longitudinal axis of the base and coaxially with the lower surface of the base.

As mentioned above, in accordance with preferred practice, the arch wire receiving groove 1 is machined when the integral bracket ring (Fig. 4) is supported in a turning machine so that the bottom surface of the arch wire receiving groove 14 is formed on a radius coaxial with the radius of the inner surface of the base and as shown particularly in Fig. 2. However, the groove may be milled at a later stage in the process, in which case it is flat bottomed.

The projection 12 includes oppositely disposed side lips 16, 17 which project outwardly beyond the lateral edges of the base 10 and which are curved on equal radii about an axis parallel to the longitudinal axis of the base. The lips 16 and 17 are undercut to form longitudinally extending channels 16A, 17A, the inner faces of which are substantially flush with the respective lateral edges of. the base. The channels 16A, 17A may be referred to as ligature wire receiving channels descriptive of their function when the bracket is used and to distinguish from the arch wire receiving groove 14.

The method of fabricating a bracket as illustrated in Figs. 1 to 3 is best described with relation to Fig. 4, which is an elevation view, partly in section, of a plurality of such brackets formed in an integral closed ring. Bracket ring 26 of Fig. 4 is developed from a piece of tubular stock or bar stock, and, for the most part, by a series of machining operations involving only a single chucking. If tubular stock of the proper I. D. is employed, no machining is necessary to develop an inside surface A. If bar stock or tubing of improper dimens ons is employed, the inside surface 20A is turned to the proper dimension. An outside surface 29B of the ring-1s machined if the O. D. of the stock employed is not of the proper dimension.

With the l. D. and O. D. of the ring established the bracket ring is formed by forming the arch wire groove 14, lips 16 and 17 and ligature wire channels 16A and 17A in a series of turning operations which may be carried out in any desired sequence either entirely or in part prior to or after the ring is cut from the parent metal and either prior to or after forming the transverse grooves which define the integral projections. In the event that any or all of these operations are performed subsequent to cut-off the ring is rechucked for such purpose.

Preferably the arch wire groove 14 is symmetrically arranged about the median plane of the ring and 1s bottomed on a radius coaxial with the radius of the inside surface of the ring identified by the reference character 20A. An arcuate arch wire groove is preferred not only for functional reasons as mentioned above, but also for reasons of manufacturing expediency. The groove is readily developed in the desired arcuate form by a s ngle turning operation which presently proves to be appreciably faster than the series of operations required to form flat grooves in each of the projecting portions of the integral ring.

The overhanging lips 16 and 17 are, as illustrated, preferably curved parallel to the circumference of the ring and also on respectively equal radii about axes normal to the axis of the ring. Again such configuration not only improves the functional characteristics of the lips and the ligature wire channels defined thereby, but also facilitates their formation since both curvatures of each lip can be formed in a single turning operation by feeding the cutting tool into the ring in a manner to develop the curvature on the axis lying normal to the axis of the ring.

The ring, during these cutting operations, may or may not remain as an integral part of the stock and is con veniently formed from an end section of the stock so that one of the edgewise lips 16 or 17 defines the end face of the stock. If the ring is integral with the parent metai during the several turning operations, a cut-off may be accomplished simultaneously with the formation of the ligature wire groove adjacent the stock, the groove being formed by undercutting the respective lip which may or may not have been shaped at this stage. There finally results, regardless of the sequence of the several forming operations, a continuous ring having uninterrupted inside and outside diameters with a continuous circumferential groove and with continuous circumferential lateral extending lips defining continuous channels. To develop individual brackets from this ring, it is grooved by milling, broaching, or any other machining technique at spaced intervals, as for example grooves 24 in Fig. 4, which each of the transverse grooves being deeper than the annular groove and definin the upper surface of the base flange between the remaining projections.

In the drawing, the grooves 24 are evenly spaced and are of uniform size so that the several radial projections are evenly spaced and are of uniform size. To produce a plurality of identical brackets from the ring 20 the base flange portion thereof is severed at the center line of each of the transverse grooves 24 so that each of the resultant individual brackets includes an integral projection symmetrically disposed with respect to the endwise extension of the base flange. For special purposes, however, it is a simple matter to alter the severance pattern so that two projections may be connected by an intervening base flange section. Referring to the lower part of Fig. 4, it is entirely practical to sever the ring, by way of example, at the points designated X and Y, so as to develop a bracket having projections 3t 31 at opposite ends of an interconnecting base flange 32. A feature of the method is that such special types of brackets may be formed as the last step of the fabricating process Without requiring any alteration of the principal formative operations.

As an alternative to the illustrated ring, the several transverse grooves (identified by reference character 24 in Fig. 4) which serve to define the radial projections may be formed at non-uniform intervals and in any desired pattern so as to develop a plurality of bracket projections of varying longitudinal dimensions. Additionally the several grooves whether uniformly or non-uniformly spaced, may be of non-uniform size so that varying flange patterns are developed. The flexibility further facilitates manufacture since patterns may be developed and established by proper machine settings which automatically turn out predetermined proportions of brackets of several dilferent sizes and flange arrangements. Such a production pattern can be developed as a function of market demands, inventory control or the like and, of course, can be easily varied by the simple expedient of adjusting machine settings to accommodate any changes in the factors upon which pattern selection is based. Essentially the only limitation upon variation within a given bracket ring is the radius of curvature of the flange, etc., as determined by the diameter of the ring.

The integral bracket ring illustrated in Fig. 4 and described in relation thereto, or any modification thereof- Lil as above mentioned, may be sold as such without cleav age between separate bracket forms. An orthodontist purchasing such integral rings can with very simple tools sever the ring as required and in the manner best suiting his individual requirements.

A modified form of the bracket of the invention is illustrated in transverse section in Fig. 5. Bracket 34 there shown is similar to the above described brackets in having a base portion 36, an integral projection 37 extending from the baseportion 36 and having a longitudinally disposed arch wire receiving groove 38 and ligature Wire receiving channels 39, 40 defined respectively by laterally extending lips 41, 42 with the inner surface of the base, the outer surface of the projection 37 and the bottoms of the arch groove and ligature grooves being curved in the direction of the longitudinal axis of the base on coaxial radii. The bracket 34 differs from those above described in that the base 36 is likewise curved in the direction of its transverse axis for the purpose of further conforming the under surface of the base to tooth surfaces. This transverse curvature may be accomplished after completion of a bracket in the manner described with relation to Fig. 4 as a furthe and final step in the fabricating operation.

Emphasis is placed on the fact that the manufacturing technique herein described not only is appreciably less expensive than present practices of making edgewise brackets, but results in a bracket which is superior to presently conventional brackets in the longitudinally oriented curvature of one or more of the transverse faces of the bracket form. it is apparent that orthodontic brackets of varying sizes and shapes may be made without significant equipment changes by the simple expedient of varying the size of the base stock and the cutting radius of the machine tools. This is a further advantage over present practices wherein materially different setups are required to manufacture flat brackets of differing dimensions.

I claim:

1. An orthodontic bracket comprising a generally arcuate base, an integral projection extending from the convex face of the base and having an arcuate outer face, the base forming a flange extending from at least one end of the projection, the projection having a groove in its outer face extending from end to end of the projection with the bottom of the groove being curved coaxially with the base, and lips extending along opposite side edges of the projection and overhanging the base to form channels opening generally away from the outer face of the projection.

2. An orthodontic bracket comprising a generally arcuate base, an integral projection extending from the convex face of the base and having an arcuate outer face, the base forming a flange extending from at least one end of the projection, the projection having a groove in its outer face extending from end to end of the projection with the bottom of the groove being curved in the direction of curvature of the base, and lips extending along opposite side edges of the projection and overhanging the base to form channels opening generally away from the outer face of the projection, the lips and channels formed thereby being curvilinear in the direction of curvature of the base.

3. An orthodontic bracket comprising a generally arcuate base having an under surface curved about a transverse axis, an integral projection extending from the convex face of the base and having an outer face curved coaxially with the base, the base forming a flange extending from an end of the projection, the projection having a groove in its outer face extending from end to end of the projection with the bottom of the groove curved coaxially with the base, and lips extending along opposite side edges of the projection and overhanging the base to form channels opening generally away from the outer face of the bracket, the lips and the bottom of the channels formed thereby being curved coaxially with the base.

4. An article of manufacture comprising a ring, a plurality of integral radial projections extending outwardly from the ring, each projection having a groove in its outer face extending from end to end thereof, and lips along its side edges overhanging the ring and forming inwardly opening channels along opposite side edges of the projection.

5. An article of manufacture comprising a metallic ring, a plurality of uniformly spaced integral radial projections extending outwardly from the ring, each projection having a g oove in its outer face extending from end to end thereof, and lips along its lateral edges overhanging the ring and forming inwardly opening channels along opposite lateral edges of the projection.

6. An article of manufacture comprising a metallic ring, a plurality of integral spaced radial projections extending outwardly from the ring, the outer face of each projection being curved about the axis of the ring, each projection having a groove in its outer face extending from end to end of the projection and bottomed on a radius of the ring axis, and lips along its side edges overhanging the ring and forming inwardly opening channels along opposite side edges of the projection, the lips being curved on a radius of the ring axis.

7. An article of manufacture comprising a metallic ring, a plurality of integral spaced radial projections extending outwardly from the ring, the outer face of each projection being curved coaxially with the ring and adjacent its lateral edges on respectively equal radii about axes transverse to the axis of the ring, the lateral edges overhanging the ring to form channels along opposite lateral edges of the projection, bottomed on a radius of the ring axis, and a groove in the outer face of each projection extending from end to end of the projection and bottomed on a radius of the ring axis.

8. An orthodontic bracket comprising a generally arcuate base curved along both its longitudinal and transverse axes, an integral projection extending from the convex face of the base, the base forming a flange extending from at least one end of the projection, the projection having a groove in its outer face extending parallel to the longitudinal axis of the base and from end to end of the projection, and lips extending along opposite side edges of the projection and overhanging the base to form channels opening away from the outer surface of the projection.

9. An orthodontic bracket comprising a generally arouate base, an integral projection extending from the convex face of the base and having an arcuate outer face curved coaxially with the arcuate base, the base forming a flange extending from at least one end of the projection, the projection having a groove in its outer face extending from end to end of the projection in the direction of curvature of the base and projection, and lips extending along opposite side edges of the projection and overhanging the base to form channels opening generally away from the outer face of the projection.

References Cited in the file of this patent UNITED STATES PATENTS 1,789,719 Weatherhead J an. 20, 1931 1,976,141 Richardson Oct. 9, 1934 2,045,025 Richardson June 23, 1936 2,134,749 Burt Nov. 1, 1938 2,378,279 Begg June 12, 1945 2,527,526 Bursse Oct. 31, 1950

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