Patent Publication Number: US-RE28889-E

Title: Method and apparatus for orthodontic treatment

Description:
BACKGROUND OF INVENTION 
     In accordance with what is known as the direct method of orthodontic work, bands are positioned around the individual teeth of a patient with brackets to permit connection of the bands to the arch wire and various spring wires as are ordinarily utilized. This technique requires considerable skill and judgment on the part of an orthodontist in manipulating and forming the various force applying wires so as to attain the desired movement of teeth. 
     In accordance with the so-called &#34;indirect&#34; method utilized heretofore, bands and arch wires are formed in an ideal model and then transferred to the patient. However, it is virtually impossible to secure the bands on the patient&#39;s teeth in the same location as on the model. 
     SUMMARY OF INVENTION 
     In accordance with the method of the invention and utilizing the apparatus of the invention, an orthodontist is enabled to perform the difficult and intricate task of forming an arch wire so as to obtain the desired tooth movement on an ideal model of the teeth of the patient while the arch wire is out of the mouth. Thereafter, the arch wire can be transferred to the patient&#39;s mouth and easily and quickly secured to the individual teeth by the novel brackets of the invention. 
     More particularly, in accordance with the method of the invention, arch wire brackets are secured by bands to the teeth of a patient after which an impression is made of the patient&#39;s mouth. After removal of the impression, replicas of the brackets are inserted in a corresponding position in the impression and a casting made of the teeth in the course of which the brackets will become rigidly attached to the tooth castings. Thereafter, the individual tooth castings are separated and reset in an ideal model of the patient&#39;s mouth whereupon an arch wire can be formed so as to conform to the bracket locations of the teeth in the ideal model. After formation of such wire, it is transferred to the patient&#39;s mouth, whereupon the memory of the wire will apply corrective force to the teeth causing them to move towards their ideal location. 
    
    
     THE DRAWINGS 
     FIG. 1 is a perspective view of a portion of a bracket made in accordance with the invention; 
     FIG. 2 is a perspective view of a so-called follower utilized in the bracket of the invention; 
     FIG. 3 is a top view of an assembled bracket; 
     FIG. 4 is a sectional view taken along line 4--4 of FIG. 3; 
     FIG. 5 is a top view of a modification of the bracket of the invention; 
     FIG. 6 is a top view of still another modification of a bracket made in accordance with the invention; and 
     FIG. 7 is an elevation on reduced scale of a modification of a snap ring adapted for use in the invention. 
    
    
     Reference is made first to FIG. 1 in which is illustrated a bracket .Iadd.body .Iaddend.10 made in accordance with the invention and which bracket comprises a base portion 12 adapted to be secured as by brazing or other suitable means to a tooth band 14 which is mounted upon the patient&#39;s tooth in any conventional manner. The bracket also includes a head portion 16 having a labial surface 18. As indicated, the base and head portions are preferably of circular configuration, but need not be so, and extending between them is a shank 20 which is of reduced diameter with respect to both the base portion 10 and the head portion 16. The head portion 16 is formed with a horizontal groove 28 therein for receiving an arch wire 30. Preferably but not necessarily both the groove 28 and the arch wire 30 are of rectangular configuration. The head portion 16 is also provided with a vertical groove 26 which in depth may be less than the depth of the groove 28 but at least is of such depth that the difference between the depth of the groove 28 and the groove 26 is not greater than the thickness of the arch wire 39 the reason for which will become apparent. 
     A second vertical groove 32 is provided in the bracket, such vertical groove extending in the present embodiment through the base and shank portions and preferably being of rectangular cross section. Extending between the grooves 26, 32 is a notch 34. 
     Referring now to FIG. 2, adapted to cooperate with the bracket 10 is a locking member or follower 38 which includes a base portion 40 of rectangular cross section adapted to be slidably received within the groove .Iadd.or guideway .Iaddend.32. Extending forwardly from the base portion 40 is an arm 42 adapted to be received in the notch 34 at the end of which arm is a locking .Iadd.portion or .Iaddend.finger 44 adapted to extend forwardly of the arch wire 30 when the same is engaged within the groove 28, the lower end of the finger 44 being received within the lower portion of the groove 26. 
     The follower 38 is adapted to be .Iadd.retained or .Iaddend.locked in place by a snap ring 46 which in turn is adapted to be engaged about the shank 20, the ends of the snap ring extending over the top .Iadd.or shoulder .Iaddend.of the follower 38 when the follower is fully inserted, as may be seen in FIGS. 3 and 4. The follower base portion 40 is formed with grooves 48 in the opposite sides thereof in which the ends of the snap ring 46 are received during retraction or insertion of the follower. Preferably the follower 38 is provided with .Iadd.first .Iaddend.means releasably to engage the snap ring in its .Iadd.first .Iaddend.partially withdrawn .Iadd.or open .Iaddend.position with the finger 44 clear of the groove 28. Such means may comprise an indentation 50 formed in one or both of the walls 52 of the grooves 48 as shown in FIG. 4, or other suitable stop means may be provided. 
     The bracket and follower are preferably formed of stainless steel or other suitable corrosion resistant, high strength metal and can obviously also be formed of high strength plastic or other material. The groove 26 and arch wire 30 are preferably of such dimension as to form a close fit, but they should, at the same time, permit some longitudinal movement of the arch wire 30 through the groove 28. Such movement is necessary, of course, to permit adjustment of the position of the bracket on the arch wire as a tooth rotates under pressure applied to it through the arch wire. Likewise, the clearance between the finger 44 and an arch wire 30 must be such as to permit sliding movement of the wire. 
     In accordance with the method of the invention, the brackets 10 and bands 14 are secured to the teeth of a patient. An impression of the patient&#39;s mouth is then taken so as to obtain an impression of the position of the teeth with the brackets attached thereto. The impression is removed from the mouth and replicas of brackets 10 are inserted in the corresponding apertures formed in the impression. Thereafter, a casting is made in the impression so as to obtain a model of the patient&#39;s teeth with the bracket replicas attached to the cast teeth. Next, the individual tooth castings are separated by cutting or other suitable means and reset in their ideal locations in a model. Next, an arch wire is formed so as to fit the brackets of the ideal model and upon its completion this arch wire is removed and attached to the brackets on the teeth in the patient&#39;s mouth. Upon attaching to the teeth in the patient&#39;s mouth, the memory of the wire will, of course, apply the desired pressure to the teeth in the mouth to cause them to rotate or tip or otherwise move as desired towards the ideal location. It may be preferred to start the treatment with a wire applying only a small amount of force and to increase the force applied as the treatment continues by changing the wire. In any case, the orthodontist can go back to his ideal model for forming the arch wire which is to positioned in the patient&#39;s mouth. 
     As will be clear from the foregoing, to attach the arch wire to the bracket the follower 38 is mounted on a bracket with the snap ring engaged in the openings 50 so that the groove 28 is clear. The arch wire 30 is then inserted within the groove 28 and positioned against the rear wall of such groove and pressure then applied to the follower 38 to cause it to move downwardly, thereby moving the finger 44 over the arch wire 30 to hold it in .Iadd.its second or locked .Iaddend.position. When the follower 38 clears the ends of the snap ring 46, they will close over the top of the follower to retain it in .Iadd.a closed .Iaddend.position. 
     To remove an arch wire the process is reversed, that is, the orthodontist opens the snap ring 46, for which purpose a suitable tool is provided. The follower 38 is then moved upwardly until the ends of the snap ring 46 engages in the indentations 50. At this point the finger 44 will have cleared the groove 28 so that the arch wire 30 can be moved sideways and out of the groove 28. While the bracket of this embodiment has been illustrated in connection with a rectangular arch wire 30, it will be obvious that round arch wires or bundles of two or more arch wires can be suitably utilized. Also, while the method of the invention has been described in connection with the brackets of FIGS. 1 to 4, it will be apparent it may also be performed with other types of brackets. 
     Referring to FIG. 5, a modification of a bracket of the invention is therein illustrated, the bracket 10&#39; of this modification comprising a base portion 12&#39; and a head portion 16&#39;, the horizontal groove 28&#39; in this embodiment being of such depth as to extend to the shank 20&#39;. Thus, the arch wire 30&#39; abuts the surface of the snap ring 46&#39;. The follower in this embodiment includes a base portion 70 fitting within a groove 72 formed in the base 12&#39;. Extending from the base portion 70 is an arm 42&#39;. The arm 42&#39; is provided at its end with a finger 44&#39; for engaging over the arch wire 30&#39; when it is fully inserted. The present embodiment has the advantage over the prior described embodiment in that the length of arch wire contact is increased to the edge of the snap ring 46&#39;, that is, to the point X&#39; compared to the point X thus increasing the torque arm for rotational inclination of a tooth. 
     Referring to FIG. 6, in still another modification of the invention, the finger 44&#34; is of enlarged cross section relative to the arm 42&#34; and the vertical groove 26&#34; of the receiving bracket is correspondingly enlarged. This has the advantage of more securely holding the follower in place than in the previously described embodiments. 
     To still further increase the rotational torque arm, the snap ring may be provided with wings 80 as shown in FIG. 7. Such wings can be provided on a snap ring as used in any of the foregoing embodiments. 
     Having described certain preferred embodiments it will be apparent that the invention permits of still other modifications in arrangement and detail.