US 3775850 A
Orthodontic apparatus employing parallel unbent arch wires in cooperation with brackets having predetermined ideal three dimensional positions built into the bracket structure for each tooth. Friction between the bracket and arch wires is minimized by using point contacts. In one embodiment, a plastic bracket may be used having snap-in slots for holding the arch wires. In another embodiment a staple may be inserted in the bracket to hold the arch wires. Both embodiments also permit the use of ligature wires to hold the arches. The unbent light arch wires may be configured in pairs, normally one above the other, or in threes, triangular or in line, to provide greater rigidity. Substantial time saving is achieved through the use of the orthodontic apparatus herein disclosed while at the same time achieving greater success with less skill by the practitioner. The invention overcomes the shortcomings of prior art "edgewise" and "light-wire" orthodontic techniques.
Description (OCR text may contain errors)
United States Patent [191 Northcutt Dec. 4, 1973 1 ORTHODONTIC APPARATUS  Inventor: Michael E. Northcutt, 1704  ABSTRACT Miramonte Ave., Los Altos Hills, Orthodontic apparatus employing parallel unbent arch Calif. 94040 wires in cooperation with brackets having predetermined ideal three dimensional positions built into the  Filed 1971 bracket structure for each tooth. Friction between the Appl. No.: 193,400
Primary Examiner-Russell R. Kinsey Assistant Examiner-J. Q. Lever Att0meyWilliam E. Schuyler, Jr. et al.
bracket and arch wires is minimized by using point contacts. In one embodiment, a plastic bracket may be used having snap-in slots for holding the arch wires. in another embodiment a staple may be inserted in the bracket to hold the arch .wires. Both embodiments also permit the use of ligature wires to hold the arches. The unbent light arch wires may be configured in pairs, normally one above the other, or in threes, triangular or in line, to provide greater rigidity. Substantial time saving is achieved through the use of the orthodonti c apparatus herein disclosed while at the same time achieving greater success with less skill by the practitioner. The invention overcomes the shortcomings of prior art edgewise and light-wire orthodontic techniques.
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l ORTHODONTIC APPARATUS BACKGROUND OF THE INVENTION The invention relates generally to orthodontics and more particularly to novel orthodontic brackets and archwires for use with suchbrackets.
A number of prior art orthodontic techniques have been tried over the years; those forming a background to the present invention will be discussed.
In the edgewise technique, t h eearl@st orthodon-' axis of the tooth to or from adjacent teeth) force it is' generated by the bracket configuration. Some orthodontists have cut the bracket slot at an angle, so as to provide a torquing (tipping of the major axis of the tooth to or from the palate) of the tooth. Differences in tooth width have been accommodated by some orthodontists by placing shims under the bracket to offset the bracket position in the horizontal plane. The basic appliance using Angles appliance with some modifications is still the standard of the art today.
In US. Pat. No. 3,477,128 tovDr. L. F. Andrews, amodified edgewise technique is disclosed in which the various modifications listed above have been brought together by the use of a cast metal bracket. Substantially greater expense is incurred in precision casting the bracket and consequently the standard edgewise arch continues to be employed. Dr. Andrews notes the need' for horizontal correction' due to' the v 2 trol is not possible with only one point contact on the teeth.
' The edgewise and Begg techniques account for 90 percent or more of current orthodontic treatment at this time. However, neither technique is satisfactory in providing precise three dimensional control of tooth movement, particularly when extreme malocclusions are encountered.
Other variations of the edgewise technique are disclosed in US. Pat. No. 2,756,502 to V. D. Bowles and US. Pat. No. 2,330,315 to S. L. Winslow. Both techniques suffer from the frictional binding and excessive force levels of the edgewise technique. In addition, the practical requirement of precision bending two independent archwires to minute angles render the techniques essentially impossible to practice.
In U.S.- Pat. No. 2,756,502 to V. D. Bowles, an orthodontic bracket having a pair of parallel grooves for accepting one or a pair of arch wires is disclosed. Although a pair of round arch wires are shown in FIG. 1 of the patent, it is suggested that the heavier and rectangular arch wires should be used in the intermediate and final phases of tooth alignment and movement. When two wires are used they must be independently bent to the exact same configuration or conflict with each other; a time-consuming procedure; Also the long groove lengths would cause greater friction with the width of the individual teeth, but does not relate such correction to a reproducible arch form. That the mere observation of anatomical differences in widths of teeth does not relate them to an overall appliance is clearly evident, in that the teeth could be placed all in a straight line and still meet the patentees criteria.
In the edgewise approach functional resistance and binding between the wire and bracket slot walls is encountered. Heavy rectangular wires of 'the magnitude of 0.022 X 0.028 inches are typically used which are usually painful to the patient and may cause root damage. Torquing movements are obtained by binding of the arch on the upper and lower slot walls of the brackets; when torquing forces are employed all other vector forces are impeded. See FIG. 17 which is described in greater detail hereinafter.
The Begg light wire technique is an attempt to avoid the painful and frequently destructive forces of the edgewise technique. This technique is described in considerable detail in an article entitled Differential Force in Orthodontic Treatment by Dr. P. R. Begg in the American Journal of Orthodontics, Vol. 42, No. 7,
July, l956, p. 48. -In this technique'only a single light round wire is used. This wire is pinned at one point only and is a substantial improvement over the edgewise technique in reducing the amount of force applied to the teeth. Frictional resistance is greatly lowered but one point control permits excessive tipping which requires great skill and diligence to overcome in later stages of treatment. Moreover, three dimensional conarch wires, thus inhibiting the desired tooth movement. In addition, the ligature tie areas are closed so that the securing wires mustbe hand-fed through slots at a further loss of time.
S. L. Winslow in US. Pat. No. 2,330,315 describes a technique using perpendicular rectangular arch wires in a dual edgewise approach. No attemptis made to ultimately position each tooth as to optimum location since each tooth bracket is identical andhas no built-in anglesor in/out spacing. The long contact between the rectangular arch wires and bracket grooves necessarily cause binding and inhibits desired tooth movement.
SUMMARY OF THE INVENTION The Ideal Occlusion Until the present invention, the science of orthodontics has largely been an art form depending largely on the clinical skill of the orthodontist. For example, no textbook defines the specific torque, tip and horizontal spatial. relation of each tooth and consequently the correct occlusion varied from practitioner to practitioner.
Considerable work by the present inventor and others has led to an understanding of ideal occlusion. There is a reference normal for teeth just as there is for eyes, ears, and other body organs. The following chart gives the relation of each individual tooth in three planes of space. Angles are related to the coronal surfaces of the teeth since that is the portion to which the bracket must relate. Horizontal relation is measured in from an ideal arch to the tooth surface.
LOWER Tooth Tip Torque In central 2 1 L3 mm lateral 2 l 1.3 mm cuspid 5 l l 0.6 mm lst biscuspid 2 l7 0.15 mm 2d biscuspid 2 22 0.l5 mm lst molar 2 30 0 mm 2d molar 2 35 0 mm UPPER Tooth Tip Torque In central 5 +7 0.8 mm lateral 9 +3 [.2 mm cuspid 11 7 0.4 mm lst bicuspid 2 7 0.5 mm 2d bicuspid 2 7 0.4 mm lst molar 5 9 mm 2d molar -9 0 mm Tip Cant of root axis away from midline (see FIG. 21)
Torque Cant of root axis toward palate (see FIG. 22)
Horizontal measurement in from ideal Bonwill Hawley arch form.
It is important that the teeth be related to anatomically correct curvature which can be printed on the treatment sheetof the patient so that the orthodontist can scientifically relate each arch to an end point blueprint. The arches may be of course modified as human arch forms vary slightly in square, tapering, and ovoid fashion.
Ideal Arch Form The ideal arch form is described in Strangs Text (Strang and Thompson p. 728-729, Leo Ferbiger, Philadelphia, Pa., 1958) as follows. Reference is made to FIG. 32.
Using as a radius the sum of the mesio-distal widths of a maxillary central, lateral and canine tooth, plus two l/l6 inch allowances placed between the central and lateral, lateral and canine measurements as described on page 732, draw the circle A-B, Plate V, placing the cente of the circle Y, on the line C-D. Maintaining the same radius but with the point of the compass at E, bisect the circumference of the circle on each side at the points F and G. Draw the lines H-.] and H-K which extended indefinitely Connect these lines by a tangential line running through E and drawn at right angles to the line C-D, thus forming an equilateral triangle H-J-K. Using the length of one side of this equilateral triangle as a radius, with the point of the compass on the line C-D, at the point L, and the pencil at the point E, construct the circle M-N. With the radius of this circle, divide its circumference six times, beginning at the point EjDraw the lines P-R and S-T.
To the radius E-Y, add one-half its length, which will give the radius E-Y-U and also 7-Z. Using this radius and placing the point of the compass at Z, which is onetenth inch below the point U, on the line C-D, construct the line 6-7-8, the center of which is one-tenth inch below the point E. The line 6-7-8 extends fivetenths inch on each side of the line C-D.
Arch Wire Cross Section A most critical factor in the design of an orthodontic appliance is the cross section of wire to be used. Small changes in cross section can dramatically influence both the maximal elastic load and the load-deflection rate.
The maximal elastic load varies directly as the third power of the diameter of round wire and the loaddeflection rate varies directly as the fourth power of the diameter. The most obvious method of reducing the load-deflection rate of an active member is to cut down the size of the wire.
The fact that load-deflection rate varies as the fourth power of the diameter in round wire suggests the critical nature of the selection of a proper cross section. A piece of 0.018 inch wire is not interchangeable with 0.020 inch wire, for with a similar activation (ignoring play in the bracket), the 0.020 inch wire will deliver almost twice as much force. The dramatic difference between wire sizes can be further demonstrated by comparing two similar activations in a 0.020 inch and 0.010 inch round wire. The 0.020 inch round wire does not deliver twice as much force but rather 16 times as much 'force, load-deflection varying as the fourth power of the diameter.
Furthermore, because of the large amount of round wire that is available for commercial purposes, the properties of the wire, including corss-sectional tolerances, are far superior in round wire than in any other cross sections.
Wire Length The length of a member may influence the maximal elastic load and the load-deflection in a number of ways, depending upon the configuration and loading of the spring. The cantilever has been chosen to demonstrate the effect of length, since the cantilever principle is widely used in orthodontic mechanisms. A finger spring may be visualized for the following discussion.
FIG. 31 shows a cantilever attached at its right end with a vertical force F applied. The distance 1 represents the length of the cantilever measured paral lel to its structural axis. Inthis type of loading, the loaddeflection rate will vary, inversely as the third power of the length. In other words, the longer the cantilever, the lower the load-deflection rate. The maximal elastic load varies inversely as the length of the cantilever. Once again, the longer the cantilever, the lower the maximal elastic load.
Increasing the length of the cantilever is a better way to reduce the load-deflection rate than reducing the cross section. Increasing the length of the cantilever markedly reduces the load-deflection rate, yet the maximal elastic load is not radically altered, since it varies linearly with the length. Added length within the practical confines of the oral cavity is an excellent way of improving spring properties. A parallel arch' technique therefore doubles the presently used lengths.
.Pressure v is not exceeded and resistance will not build up.
Since the orthodontic forces frequently act through moment arms on the root, even tipping forces encountered in so-called light-wire techniques may result in incredibly high pressures. Useful discussions concerning excessive force in orthodontics are found in Technique and Treatment With the Light-Wire Appliance, Joseph R. Jarabak and James A. Fizzell, C. V. Mosby Co., St. Louis, I963; A Critique of the Begg Technique From the Standpoint of Biomechanics," Jack Perlow, American Journal of Orthodontics, Vol. 54, No. 6, June, 1968, pp. 407-432; Force-Induced Changes in the Vascularity of the Periodontal Ligament, Anthony A. Gianelly, American Journal of Orthodontics, Vol. 55, No. 1, January, 1969, pp. 5-11, and A Study of Root Resorption in Treated Class II, Division I Malocclusions, Robert W. DeShields, The Angle Orthodontist, October, 1969. Oppenheim, A.: Possibility for Orthondontic Physiologic Movement. American Journal of Orthodontics, Vol. 30, 277-345, I944. (T.M. Graber, Current Orthodontic Concepts and Techniques, W.B. Saunders Company, Philadelphia 1969.
The present invention is concerned with the compounding of light forces in order to achieve maximum tooth movement without applying excessive pressure to the alveolar process. Light arch wires of high resiliency are employed. The basic philosophy underlying this in-' vention is to provide a light sustained pressure of greater duration, rather than the current heavy pressures employed by the edgewise technique.
Appliances According to the Present Invention tic bracket is provided for cooperation with a novel arch wire. In one embodiment the bracket is particularly adapted for being formed from plastic material; in a further embodiment the bracket is formed from soft metal. In one preferred embodiment the arch wire is a single pair of parallel unbent light round wires; additional embodiments of the arch wire include three such wires arranged in a triangular cross section and three such wires arranged in line.- v
An orthodontic bracket is provided for each tooth having a base surface following the general curve of the particular tooth. Since the bracket may be formed of plastic or soft metal the base may be adapted exactly to the particular tooth with seating pressure. Four point contacts are provided in the bracket for receiving arch wires; these point contacts completely geometrically define the ideal three dimensional location of the respective tooth (end point'tip angle, torque angle and horizontal offset distance as defined above), with respect to the arch wires which conform to the ideal arch form (FIG. 27 ).The arch wires are secured together in a pair or in threes to define a plane. In the plastic embodiment of the bracket, V-shaped slots taper to a point beyond which the arch wires may be snapped' in to secure the arch wires in low friction point contact rings.
In accordance with the present invention, the orthodontic bracket for each tooth has a predetermined structure that cooperates with the unbent light wires to cause the application of the aforementioned three di-- mensional forces to ultimately bring the teeth into their anatomically ideal relationship.
Present techniques require 45 minutes per patient for the construction of one pair of arches (upper and lower). It is extremely difficult to bend with precision all the angles required. With the current invention arch One basic effect of the present appliance is to replace the heavy arch of conventional appliances with a gentle push-pull force. Pairedarches will greatly help to eliminate the occurrence of undesired collateral effects such as tipping of teeth; thus, a duplication of movements and retracing of previous corrections may be minimized.
Since only light forces are encountered, the bracket itself can be stamped from soft metal, thus saving the expensive manufacturing costs encountered in casting or precision machining. Also, the light forces permit fabrication of the bracket in plastic or similar resinous material. The latter materials, unlike metal, can be affixeddirectly to the tooth by any suitable cement such as epoxy resin to thereby eliminate the intermediate tooth band. Plastic brackets have generally been found unsuitable for .use with heavy wires employed in the edgewise orthodontic technique because the heavy forces involved loosen the brackets from the teeth. 7
Pain is a response to pressure. Pressure Force per unit of area. By reducing wire diameter from 0.020 to 0.010 inches a 16 fold reduction of force occurs. Two 0.010 inch wires an 8 fold reduction in force. Using an area spread over four points increases the area and the pressure is reduced further. The pressure levels are reduced to be in harmoney with the biomechanics of tissue physiology. Currently patients often leave the orthodontists office in tears and suffer considerably for several days. By practicing the present invention, pain should be greatly reduced sinceno other appliance is designed to function at such light force levels.
A virtually friction free cooperation between bracket and arch is achieved through the use of four point con- 5 tacts. Rings are designed 0.020 thousandths in diameter, and considerable play exists using wires of 0.010 diameter either singly or in pairs. It is intended that the rings be coated with low friction material such as Teflon in order to further reduce friction. In addition, wires coated'with low friction material such as Teflon may also be used that are fabricated by the new plasma and metal oxide deposition techniques developed recently by the spaceand electronic industries. The same I 1 well known deposition techniques may be used to facilwires willbe unbent and may be prefabricated at the factory to the ideal curvature. A template of the Bonwill arch may be superimposed on the patientss starting models and selected-for the specific patient. Acetate forms as shown in FIG. 33 may be employed. These may be printed on the treatment sheet so'that like a blueprint the work follows a logical sequence and precision from beginning to end.
All manner of auxiliaries may be used in conjunction with the orthodontic appliances according to this invention.
itate the cementation of the brackets. A tremendous time loss is presently experienced in recementing loose bands'This' may be essentially eliminated by oxide and other depositions inside the band as the weak bonding area is currently the slick metal surface. Similarly such depositions greatly facilitate the direct cementation of plastics to tooth surfaces.
In the case of plastic brackets the wire may be snapped to place without hand tying: hand tying takes approximately fifteen minutes or more for a pair of arches.
In the stamped metal bracket, a tube may be used to receive staples for holding the arch wires, a great time sever over current tying.
This technique more than any other lends itself to the direct cementation of plastic brackets to tooth surfaces. The heavy forces involved with the edgewise technique have tended to'distort and pullloose such brackets. Current time for handing. requires 3 to 4 hours. With direct cementation the current invention should facilitate an immediate saving of much of this time.
Arch length is doubled by the use of two wires with advantages as previously discussed under wire length.
This, coupled with the more resilient use of low diameter wires will allow for a sustained light force application over a greater length of time resulting in appointment intervals at 6 weeks instead of 3. Moreover, since the practitioner need not make any bends in the arch wires another 45 minutes time is saved whenever new upper and lower arch wires are placed. This is coupled to a tying time saving of ID to l minutes. Friction is greatly reduced allowing for faster and more efficient movement of the teeth further reducing .the treatment time.
This appliance will facilitate the use of tooth colored plastic brackets getting away from the tin look.
Pressure injected plastic brackets and stamped brackets are not currently used due to the heavy forces presently required bythe edgewise technique. A great reduction in cost will be achieved by their use. In addition, round wires are greatly cheaper than milled edgewise wires of minute dimensions such as 0.022 X 0.028 thousandths (the conventional wire). The same fundamental bracket form may be used with a few modifications for most teeth, the major variable being the positioning of the ring points. This is a reat savings over other techniques such as Andrews where rights and lefts are different and require expensive casting procedures for each tooth. The greatest saving occurs in the orthodontists time. It should be possible to reduce banding and arch time as well as tie in time to the point where two to three times as many patients can be treated at half the price.
Many adults are, desperately in need of treatment but fail to receive help due to their self-consciousness regarding bands. The use of plastic brackets should extend treatment to many now out of reach.
Since arches require no bends general dentists will be able to incorporate orthodontics into their scope of treatment. At present the intricate angles and bends required limit orthodontics to a select few who have been able economically to afford to take the additional two years training required to develop this skill. The result is that there are approximately 125,000 dentists in the BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of one preferred embodiment of the orthodontic bracket according to the present invention shown affixed to a tooth.
FIG. 2 is an elevational view along lines 2-2 of FIG. 1.
FIG. 3 is an elevational view along lines 33 of FIG. 1.
FIG. 4 is an enlarged cross-sectional plan view along lines 4-4 of FIG. 3.
FIG. 5 is a broken away elevation view along lines 5-5 of FIG. 4.
FIG. 6 is a perspective view of a further preferred embodiment of the orthodontic bracket according to the present invention shown affixed to an orthodontic tooth band.
' FIG. 7 is an elevation view along lines 7 7 of FIG. 6.
FIG. 8 is an elevation view along lines 88 of FIG. 6.
FIG. 9 is an elevation view, similar to FIG. 8, of an upper molar bracket according to the present invention.
FIG. 10 is an elevation view, similar to FIG. 8, of a lower molar bracket according to the presentinvention.
FIG. 1 l is a perspective view of a geometric plane defined by the parallel arch wires of the present inven tion.
FIG. 12(a) is a perspective view of one embodiment of the parallel arch wires according to thepresent invention.
FIG. 12(b) is a perspective view of a variation of the parallel arch wires of FIG. 12(a).
FIG. 12(0) is a perspective view of a further variation of the parallel arch wires of FIG. 12(b).
FIG. 13 is a perspective view of a further embodiment of the parallel arch wires according to the present invention.
FIG. 14 is a perspective view of a further embodiment of the parallel arch wires according to the present invention.
FIG. 15 is an elevation view of the arch wires of FIG. 12 attached to a bracket according to the present invention.
FIG. 16 is an elevation view of the arch wires of FIG. 14 attached to a bracket according to the present invention.
FIG. 17 is an enlarged cut-away elevation and crosssectional view of the prior art edgewise orthodontic technique when a rectangular arch wire is inserted into a rectangular bracket slot.
FIG. 18 is an enlarged cut-away elevation and crosssectional view view of the orthodontic technique of the present invention where a pair of light circular arch wires are inserted into a pair of V-shaped slots for bold ing at a pair of point contacts.
FIG. 19 is a perspective view of a left upper central incisor illustrating the terminology conventionally used todescribe the planes and directions associated therewith.
FIG. 20a is a plan view of a molar illustrating the terminology for distal axial rotation.
FIG. 20b is a plan view of a molar illustrating the terminology for merial axial rotation.
FIG. 21 is an elevation view along the labial-lingual axis of a central incisor illustrating tipping correction.
FIG. 22 is an elevation view through the mesial-distal axis of the tooth of FIG. 21 illustrating torquing correction.
FIG. 23 is a perspective view of bracket and arch wires according to the present invention showing the flexing of the arch wires in early stages of correction.
FIG. 24 is a plan view of a molar having bracket and arch wires according to the present invention, showing the flexing of the arch wires to produce a mesial rotational force. FIG. 25 is a perspective view of the brackets according to the present invention attached to a central incisor and cuspidillustrating the use of parallel retraction arches.
FIG. 26 is a plan view of a typical set of teeth showing the correction technique when teeth are so far out of line that the arch wires cannot be flexed to reach the teeth.
FIG. 27 is a schematic elevation view of several brackets according to the present invention with spring auxiliaries.
FIG. 28 is a perspective view of a bracket according to the present invention and a tooth, showing the bracket coding and the notches for lining up the bracket on the tooth.
FIG. 29(a) is an elevation view showing the desired torque angle for the right lower'teeth.
FIG. 29(b) is an elevation view showing the desired tip angle for the right lower teeth.
FIG. 29(0) is a plan view showing the desired in spacing of the right lower teeth with respect to the unflexed arch wire.
FIG. 30(a) is an elevation view showing the manner in which the bracket in cooperation with the arch wires according to the present invention provide the desired tip correction.
FIG. 30(b) is an elevation view showing the manner in which the bracket in cooperation with the arch wires of the present invention provide the desired torque correction.
FIG. 30(c) is a plan view showing the manner in which the bracket in cooperation with the arch wires of the present invention provide .the desired in spacing from the arch wires.
FIG. 31 is a schematic view illustrating a mechanical principle useful in understanding the present invention.
FIG. 32 is a schematic diagram for use in deriving an ideal arch form.
FIG. 33 is a portion of an orthodontists record for a particular patient, illustrating the use of the ideal arch forms.
DESCRIPTION OF THE PREFERRED EMBODIMENTS elements. The orthodontic bracket 2 comprises a uni tary structure having a'base portion4. The bracket is preferably formed by injection molding of phenolic resins, epoxies, plastics and any other structural materials that are suitable and capable of being injection molded.
The bracket may also be formed from soft metal. Base 4 is generally curved to approximte'the tooth contour so that it conforms exactly to the tooth contour with seating pressure applied by a I hand tool when the bracket is installed. In this embodiment a tooth encircling band is not necessary. The back side of base 4 has an oxide deposit layer 5 to facilitate cementation of the plastic ormetal bracket to the tooth 9 by epoxy resin or other means. The deposit layer 5 may be any suitable layer of metal, silicon, etc. deposited by well known techniques as used in electronic microcircuit technology, for example. A pair of parallel vertical ridges 6 and 8 are widely spaced on the bracket base 4. Desirably, the ridges are located as widely apart as possible for the geometry of the particular tooth to which the bracket is to be affixed. The length of the ridges 6 and 8, and hence of the bracket base vertical dimension, with which they are coextensive, is also as great as possible the greatest control over the ,tooth. Two V-shaped slots 14 are provided crosswise in each ridge. Each slot tawhere it is held by ring 15. Ring 15 is tapered so that only a narrow circular periphery contacts the arch wire to minimize friction; The inner peripheral portion of ring 15 may be coated with a low friction material 17, such asTeflon, to further reduce friction. Four notches 22 are provided in the ends of ridges 6 and 8 for use in holding a ligature wire 24 in place. The ligature wire 24 may be used in addition to the snap-in rings 15 to hold the arch wires 16 and 18.
Alternative embodiments of the basic bracket as described in FIGS. l-5 are shown in FIGS. 6-10. These embodiments are intended to be fabricated from metal and attached to the tooth by means of -a conventional tooth band 3. It is possible, however, to employ a plastic bracket in combination with a tooth band in practicing this invention.
The orthodontic bracket 2 preferably comprises a unitary structure of soft metal having a base portion 4. Base 4 is generally curved toapproximate the tooth contour so that it conforms exactly to the tooth contour with seating pressure applied by a hand tool when the bracket is installed. The back side of base 4 is welded to a tooth band 3. A pair of parallel vertical ridges 6 and 8 are widely spaced on the bracket base 4 as in the embodiment of FIGS. 1-5. The top portion of ridges 6 and 8 are flared to define a pair of open-ended tubes 10 and 12, respectively. Two V-shaped slots 14 are provided crosswise in each ridge. As explained below, each slot depth is significant and is predetermined for the tooth on which the particular bracket is to be used. The V-shape of slots 14 facilitates the reception of arch wires 16 and 18. The top surface of ridges 6 and 8,'and hence the axes of tubes 10 and 12, are dimensioned so that arch wires 16'and 18 are held against the bottoms of slots 14 when the U-shaped staple 20 has its parallel arms inserted in tubes 10 and 12. Four notches 22 are provided in the ends of ridges 6 and 8 for use in holding a ligature wire (not shown) in place. The ligature wire may be used instead of staple 20 to hold the arch wires 16 and 18. Thus, the practitioner has the option of two methods to secure the arch wires.
As will be explained further below, the brackets of FIGS. 1-8 can be used with either one 'or two arch wires. Also, as shown in examples below, either or both tubes 10 and 12 can be used for auxiliaries when the ligature wire 24 instead of the staple 20 is used to hold the arch wires.
In FIG. 9, a further alternative embodiment of the bracket of FIGS. 1-8 is shown. The bracket of FIG. 9
i is an upper molar bracket: since this bracket is located in terms of the particular tooth size in order to provide at the end of the arch wires when installed, a plurality of holes 30 areprovided' instead of slots 14 in a single ridge 8. The arch wires may thus be inserted directly in the holes 30. The tubes 10 and 12 for holding a staple 20 ,are thus also omitted. A tube 32 having its major axis disposed generally parallel to the arch wires that are inserted in holes 30 is provided for accepting headgear wires. I
FIG. 10, shows a lower molar bracket, similar to the upper molar bracket of FIG. 8. The lower molar bracket has a single ridge 8 in which a pair of holes 30 are provided to accept the arch wires. No headgear tube is provided.
A set of parallel unbent light-wire arch wires suitable for use with the brackets of FIGS. 1-10 are shown in FIGS. 12(a-c). The upper and lower arch wires 34 and 36 are substantially identical and conform, for example, to the conventional Bonwill arch form. Arch wires 34 and 36 are light wires of round cross section. In accordance with the teachings of this invention, arch wires 34 and 36 are not bent by the practitioner prior to their installation. As explained below, some flexing of the arch wires occurs when installed, but it is intended that the arch wires are not permanently deformed when installed. Several connecting wires, including a wire 38 at the midline of arch wires 34, 36 and two symmetrically disposed wires 40 and 42 distally spaced from the midline wire 38, hold the two arch wires one above the other in substantial registration in FIG. 12(a). The wires may be soldered, for example. Thus, the planes defined by arch wires 34 and 36 are parallel and wires 38, 40 and 42 are perpendicular to those planes. A pair of frontward opening hooks 44 and 46 can be located distally along the arch wires for use with auxiliaries or headgear. The hooks can be soldered to the arch'wires 34 and 36.
In order to provide a greater force at the upper or lower slots of the bracket 2 (FIGS. 1-10), the arch wires 34 and 36 can be offset so that the midline of one extends farther forward than the other. The arch wires remain in parallel planes. Thus, the midline connecting wire 38 is no longer vertical, but is angled when viewed from the side. FIG. l2( b) shows the lower arch wire 36 farther forward than upper arch wire 34. FIG. 12(c) shows the upper arch wire 34 farther forward. These configurations of FIGS. 6(b) and 6(c) are useful during theearly phase of treatment particularly in extreme cases of hypoand hyper-divergence.
FIG. 11 is intended to show a basic geometric concept underlying the parallel archwires of this invention. The parallel wires 34 and 36 lie in a curved plane 37 that conforms to the ideal arch fonn. Each bracket 2 (FIGS. 1-10) has four contact points 39, 41, 43, 45 that completely define a three dimensional spatial location. Hence, by constructing each tooths bracket by properly choosing the slot depths (and ring positions), the tooth's three dimensional orientation is completely determined.
FIGS. 13 and 14 show two further variations of the basic arch wire configuration as shown in FIG. 12. In FIG. 13 a third arch .wire 35 is provided outside the two inside wires 34, 36. Viewed in cross section, a triangle is formed by the three wires 34, 35, 36. Additional connecting wires 40', 40", 38', 38", 42 and 42" are provided to secure the three wires together. Hooks 44 and 46 are accordingly modified to mount on the triangularly configured arch wires. The triangular arch wires of FIG. 13 are usable with the brackets of FIGS. 1-10 without modification to those brackets, as shown in FIG. 15.
In FIG. 14 the third wire 35 is provided in line" or in the same plane 37 (FIG. 11) as arch wires 34 and 36.
All three wires are held together by vertical wires 38,
40, 42 as in FIG. 12. A modified bracket as shown in FIG. 16 having a third slot 14' is required to accept the third arch wire 35.
The addition of the third wire 35 as shown in FIGS. 13 and 14 provides additional rigidity and force which may be helpful particularly in the final phases of treatment.
FIG. 17 shows a portion of a prior art edgewise bracket 49 having a rectangular arch wire 53. The wire 53 is bent by the orthodontist to its solid line position to have a torque axis as shown in the front teeth area to tip the roots to axis AA. The wire is flexed to axis AB (53') and inserted into slot 51. Ultimately, the bracket and tooth rotate to the desired torque axis AA (49'). During rotation the edgewise arch wire 53 binds at the surfaces of slot 51 to inhibit movement of the bracket and tooth in any other planes.
Conversely, the point contact provided by the brackets 2 and round arch wires of FIGS. 1-16 provide virtually friction free contact that permits simultaneous correction in all planes of motion. The parallel vertical arch wires 34, 36 are flexed and inserted into the slots 14. The greater pulling action of the upper wire 34 results in the rotation of the bracket and tooth to bracket position 2.
In order to lay a precise semantic groundwork for the discussion to follow, FIGS. 19 and 20 show the basic directions used to describe tooth orientation, translation and rotation. In FIG. 19 the terms are applied to a left upper central incisor 48. It will be apparent that the terms are equally applicable with appropriate changes to anterior teeth and lower teeth. Thus, the
mesial direction is always a direction along the arch toward the mesial plane (the median vertical longitudinal plane that divides the mouth into right and left halves). Many orthodontic references refer to tipping and torquing. In terms of FIG. 19 tipping is a rotation along the buccal-lingual axis so that the root moves distally of mesially and torquing is a rotation along the mesial distal axis. Rotation along the major axis of the tooth, the apical-occlusal axis is shown in FIG. 20. In FIG. 20(a) a molar'50 is shown with reference to distal axial rotation. FIG. 29(b) shows'molar 50 with reference to mesial axial rotation. It will be apparent that a combination 'of forces and moments may simultaneously act on a tooth in a complex manner to bring about the desired correction.
FIGS. 21-24 show a bracket 2 in position on a central incisor 48..In FIG. 21 an elevation view along the labial-lingual axis shows the tipping correction action. The solid lines show the uncorrected position of incisor 48; uncorrected apical-incisal. axis of incisor 48 is shown by line 52. It is desired to tip the tooth to a corrected position at 48 as shown in dashed lines. The corrected occlusal-apical axis is shown by line 54. The angle between the uncorrected and corrected axis (lines 52, 54) is 0:. Arch wires 34 and 36 are flexed due to the uncorrected position of tooth 48. Thus, a pair of forces 56 and 58 act along the ridges 6 and 8 as the arch wires 34 and 36 push against slots 14 to form a force couple to exert a mesial tipping force. As the tooth tips toward its corrected position the arch wires are less and less flexed until they become horizontal when the tooth is at corrected position 48' as shown by dashed lines 34 and 36'. It will be noted that the angle formed between the line of the arch wires between slots 14 when the tooth is uncorrected and the final horizontal position of the arch wires is the angle a. Thus, by properly choosing the vertical locations of slots 14 for the desired corrected tip angle of the tooth, the proper tipping forces are exerted by arch wires 34 and 36 to achieve correction. Thus the angle between the slots 14 and a horizontal line through bracket 2 is the final tip angle of the tooth.
At the same time the tipping correction of FIG. 21 is taking place, torquing correction shown in FIG. 22 occurs. FIG. 22 is an elevation view through the mesialdistal axis of tooth 48. In its uncorrected position, tooth 48 has an apical-incisal axis shown by line 60. The desired torquing angle is shown with the 'tooth in dashed lines at 48 with an apical-incisal axis of line 62. In the uncorrected position of tooth 48, arch wires exert push-pull forces 64 and 66 forming a force couple to rotate the tooth lingually along the mesial-distal axis. When the arch wires 34, 36 are vertical with respect to each other, tooth 48 is in its desired position. Thus the depth of slots 14 determine the final torque angle of the tooth and also the distance of the tooth from the arch wires (the in/out distance). FIG. 23 shows the manner in which arch wires 34 and 36 are flexed when tooth 48 is in its uncorrected position to provide the torquing forces. It will be apparent that the forces resulting from the flexed arch wires act ing on the angles built into the bracket slots 14 can cause translatory motion of the tooth in any combina-' tion of the three directions shown in FIG. 19. I
FIG. 24 shows a mesial rotational force acting on tooth 48. It is to be understood that such a force may occur simultaneously with the forces described in FIGS. 21-23. FIG. 24 is a bottom view along the incisal-apical axis. Since the uncorrected position of tooth 48 is not parallel to arch wires 34, 36 there is a flexing of the arch wires in order to reach the slots in ridge 8. Thus, a force 68 tends to rotate the tooth mesially around the incisal-apical axis. The four-point contact locations are defined in terms of the ideal final arch by locating the slots 14 along ridges 6 and'8 and by con trolling the slot 14 depths.
FIG. 25 shows a perspective view of an orthodontic installation according to the present invention having a set of brackets 2 cemented to a central incisor 72 and a cuspid 74. For an understanding of this example the entire mouth need not be shown. A pair of parallel re-' traction arches 80 and 82 are shown installed in the brackets 2. Retraction arches 80 and 82 each have a pair of symmetrically disposed springs 84. The use of a single retraction arch 82, or the pair of retraction arches as shown in FIG. 13, is particularly useful in early phases of treatment of severely maloccluded teeth. The bracket 2 permits the use of two such retraction arches thereby permitting a more balanced retraction force than would be achieved with-a single arch wire and also increasing the length of time between office visits.
In FIG. 26 the lateral incisors 86 and 88 are so far out of line that the arch wires 34, 36 cannot beflexed to reach the brackets. In order to move the lateral incisors out along the labiaHingual axis a plurality of ligature wires 90 are tied from the arch wires 34, 36 to the brackets 2. The ligatures are tied so that some flexing of the arch wires occurs to exert a force on the lateral incisors. By using four sets of ligature wires attached to the four slots of each bracket 2, a greater degree of control over the lateral incisors may be accomplished so as to provide, for example, rotational correction of the incisors at the same time that the teeth are translated labially.
FIG. 27 shows the use of the bracket tubes 10 and 12 with a pair of spring auxiliaries 92 and 94, respectively. In the example of FIG. 27, the center bracket 2 is attached to a tooth (not shown) that has a tipping angle too extreme for seating the arch wires 34, 36. Thus some initial correction by means of auxiliaries is required until the tooth is rotated far enough to seat the arch wires in bracket 2. Spring 92 has its remote end corrected to tube 12 of bracket 2" and spring 94 has its remote end connected to arch wire 34 by means of a hook 95. Ligature wires (not shown) are employed to hold the arch wires 34, 36 in the slots 14 of brackets 2" and 2" when the bracket of FIGS. 6-8 is used. Alternately, a single spring 92 or 94 can be used.
FIG. 28 shows a plastic bracket 2 as shown in FIGS. 1-5 in greater detail. A symbol such as a conventional dental symbol for a particular tooth, may be molded into each bracket. Such a symbol may also be provided in the metal brackets. The bracket for each tooth, which is different, is thus easily distinguished by the practitioner. In addition, four notches 93, 95, 97, 99 may be provided along the edges of the bracket which is used without a band to facilitate its proper alignment and affixation on the tooth. Light pencil markings 101 may bemade on the tooth 9 to ease such alignment.
FIG. 29 shows what is believed to be the desired torque angle, tip angle, and in/out distance of the right lower teeth. A similar relationship is known for the upper teeth and is set forth in the table above. These relationships are thought to be the ideal relationship for the human mouth existing in nature. The brackets according to this invention have the four-contact points arranged to achieve these relationships for each tooth. It will be apparent that a practitioner may choose relationships at variance with the angles and in/out distances shown here. The invention does not depend on these particular relationships; the significant point is thatja choice, of some finaltorque angle, tip angle, and in/out distance is made and consequently the bracket foreach tooth has its slots arranged so that the desired tooth position is achieved when the arch wires are unflexed. Since each tooth has slightly different angles or in/out distance, the bracket intended for each tooth is different. Referring to FIG. 29(a), the torque angles for the central incisor, lateral incisor, cuspid, first bicuspid,
' second biscupid, first molar and second molar are 1,
1111 and respectively. measured from a line perpendicular to the horizontal. Referring to FIG. 29(b) the tip angles for the above listed teeth are 2, 2, 5, 2, 2, 2, and 2, respectively, measured from a line perpendicular to the horizontal. FIG. 29(c) shows the in/out distances in millimeters with respect to an unflexed arch wire.
In FIG. 30 the configuration of slots 14 of a bracket 2 intended for use with the cuspid is shown.FIG. 30(a) shows the arch wires 34, 36 in their ultimate vertical position. An 1 1 angle is formed between the arch wires and the tooth: the desired torquing angle. FIG. 30(b) shows the arch wires'34, 36 in their ultimate horizontal position. A 5' angle is formed between the arch wires and the tooth: the desired tipping angle. FIG. 39(c) shows 30(c) distance between the vertical arch wires and the tooth surface as 0.6 mm.: the desired in/out distance.
The invention thus described comprises novel appliances for a unique orthodontic technique having all variables designed into the appliances in harmony with nature and the physice of wires and biomechanical forces. The technique differs substantially from the Begg light wire technique which has a bracket pinned at only one point and lacks three dimensional control. It differs from the edgewise technique which relying on a single arch and heavy forces encounters frictional binding. By means of the novel brackets disclosed parallel arch wires are practical since congruent arches may be placed without binding. It will be apparent that the invention as described may be practiced other than with the specific apparatus disclosed by making modifications apparent to those of ordinary skill in the art once the invention is known by this disclosure. Thus, it is to be understood that the invention is to be limited only by the scope of the appended claims.
1. An orthodontic system for gently and efficiently straightening a row of teeth, including in combination:
a. a plurality of round light arch wires normally in parallel planes with each arch wire end anchored to a molar,
b. a series of orthodontic brackets attached to teeth lying between and forward of said molars, each said bracket having arch wire receiving means to hold said arch wires, each said arch wire being slidable with respect to and rotatable within its receiving means, said receiving means holding said arch wires spaced apart at an angle across the tooth corresponding to a predetermined tip angle for each individual tooth to which said bracket is secured, said arch wire receiving means being located relative to the rear surface of said bracket facing the tooth and a predetermined torque angle for each said tooth,
c. said arch wires being flexed into and held by said receiving means whereby torquing, tipping and/or horizontal in-out forces are applied to said teeth.
2. The system of claim 1 wherein the predetermined tip and torque angles are ideal angles and the in-out distance corresponds to an ideal arch for the patient.
3, The system of claim 1 wherein two round arch wires are employed.
4. The system of claim 1 wherein three round arch wires are employed.
5. The system of claim 1 wherein said brackets include a pair of outward extending ridges adapted to receive round arch wires, each of ridges having apertures therein.
6. The system of claim 1 wherein said brackets include a pair of outward extending ridges adapted to receive two round arch wires, each of said-ridges having two apertures therein, and said arch wires comprise two arch wires having securing means to secure said arch wires in parallel planes and said arch wires aligned one above the other and spaced from one another.
7. The system of claim 1 wherein said brackets include a pair of outward extending ridges adapted'to receive two round arch wires, each of said ridges having two apertures therein and said arch wires comprise three arch wires having securing means to secure said arch wires in parallel planes with said arch wires spaced apart and with two of said arch wires aligned one above the other and the third arch wire spaced laterally forward and between the planes of said other two arch wires so that said three arch wires form a triangle when viewed in cross section.
8. The system of claim 1 wherein said brackets include a pair of outward extending ridges adapted to receive three round arch wires, each of said ridges having three apertures therein and said arch wires comprise three arch wires having securing means to secure said arch wires in parallel planes and said arch wires aligned one above the other and spaced from one another.
9. The system of claim 1 wherein the arch wires are held by receiving means having a cross-sectional configuration that is a circular arc.
l0. Orthodontic bracket comprising a base having a front face and a back side, said back side adapted for attachment to a tooth or to a tooth band,
said front face including receiving means for a plurality of round arch wires in parallel planes, the crosssectional configuration of the arch wire receiving means including a circular arc,
said arch wire receiving means being slidable with re- 'spect to said arch wires and contacting said arch wires along their length sufficient to hold said wires spaced apart at an angle across the tooth corresponding to a predetermined tip angle, said arch wire receiving means being located relative to said back side at a predetermined in-out distance and a predetermined torque angle whereby torquing, tipping and/or horizontal in-out forces are applied to said tooth when said arch wires are flexed into place in said receiving means.
. 1 1. The bracket of claim l0 adapted for cementation directly on a tooth.
12. The bracket of claim 10 formed from a plastic material.
13. The bracket of claim 10 wherein'said receiving means hold each of said arch wires with at least two contacts.
14. The bracket of claim 10 wherein said front face further includes means for receiving an auxiliary orthodontic device.
15. The bracket of claim 10 wherein said means for receiving a plurality of round arch wires comprises a pair of outward extendingridges, each of said ridges having wire retaining slots extending from the front of said ridge toward the back side of said ridge.
16. The bracket of claim 10 wherein said means for receiving a plurality of arch wires comprises a pair of outward extending ridges adapted to receive two arch wires, each of said ridges having a pair of apertures therein. 1
17. The bracket of claim 15 wherein the top of said ridges are flared to define a pair of open ended tubes to receive a U shaped staple having its arms inserted in said tubes for holding arch wires in said slots.
18. The bracket of claim 15 wherein said bracket is formed from a plastic material and wherein said means for receiving a plurality of arch wires comprises a plurality of slots each having a narrow snap neck portion.
19. The bracket of claim 18 wherein the inner peripheral edges of said slots are tapered to a narrow surface.
20. The bracket of claim 10 wherein said predetermined tip angle, in-out distance and torque correspond to ideal angles for said tooth when said arch wires are not flexed.
21. The bracket of claim 12 which is tooth colored. 22. An orthodontic arch wire apparatus for use in combination with a bracket attached to a tooth, said apparatus comprising three light round arch wires in parallel planes, said wires conforming to smooth arch form of a size and configuration to substantially conform to the teeth in a human mouth, and means for securing said arch wires in a predetermined relationship to each other, whereby said wires apply torquing, tipping and/or horizontal in-out forces to the tooth when said wires are pre-stressed and connected in slidable and predetermined three dimensional relation to the bracket base. 23. The combination of claim 22 wherein the plurality of arch wires comprise three arch wires and said securing means secures said arch wires with the planes in which said arch wires lie parallel with said arch wires spaced apart and with two of said arch wires aligned one above the other and the third arch wire spaced laterally forward and between the planes of said other two arch wires so that said three arch wires form a triangle when view in cross section.
24. The combination of claim 22 wherein the plurality of arch wires comprise three arch wires and said securing means secures said arch wires with the planes in which said arch wires lie parallel and said arch wires aligned one above the other and spaced from one another.
25. The combination of claim 22 wherein said arch wires are coated with low friction material.
26. The apparatus of claim 22 wherein said arch form is an ideal arch form.