Abstract:
An orthodontic bracket defining a wire guide therethrough is described. The bracket includes first and second planar surfaces in the wire guide. The first planar surface is disposed at a predetermined angle from the second planar surface so that the first and second planar surfaces act as stops to limit tipping of the bracket when either planar surface abuts a wire disposed through the wire guide. In this manner the bracket incorporates stops to prevent the over-correction of a tooth during an orthodontic procedure.

Description:
[0001]    This application relies for priority on U.S. Provisional Patent Application Ser. No. 60/211,226, entitled “IMPROVED ORTHODONTIC BRACKET,” which was filed in the name of Dr. Harry K. Lerner on Jun. 13, 2000. The contents of that application are incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention concerns an improvement to an orthodontic bracket. In particular, the present invention concerns the shape of a channel that forms the bottom portion of a wire guide through the orthodontic bracket. More specifically, the improvement is directed to the shape of the surface of the bottom portion of the wire guide that contacts a wire disposed therethrough. The bracket is designed to be used with the commonly known light wire and edgewise corrective techniques, either singly or in combination.  
         BACKGROUND OF THE INVENTION  
         [0003]    The Applicant for the present invention is also the patentee for the following three patents, U.S. Pat. No. 5,037,297, U.S. Pat. No. 4,941,825, and U.S. Pat. No. 4,838,787. All three patents describe orthodontic brackets of a type known in the prior art. All three patents are incorporated herein by reference.  
           [0004]    In conventional orthodontic treatments, two methods of treatment are primarily used. The first technique is known as the edgewise technique, which consists of applying moving force to the tooth by the use of a bracket having a rectangularly sectioned arch wire receiving slot with an arch wire received therein. The tooth is moved by the application of angular torque to the bracket by the square sectioned arch wire. This torque is transferred to the underlying tooth, attached to the bracket, which then moves in the desired direction. A variation on the edgewise technique is the straight wire technique. In the straight wire technique, the torque and angulation are preadjusted in the bracket.  
           [0005]    The second technique uses a lighter wire and is known as the Begg light wire technique. This technique is characterized by the application of a light, round-sectioned arch wire, the force being applied to the tooth bracket by a different form of attachment of the light wire to the bracket. The result is similar to that of the rectangularly sectioned arch wire in that the energy stored in the wire by spring means is transferred to the tooth over time. It is very useful to have the versatility of a combination bracket that allows the use of either technique singly or both techniques simultaneously.  
           [0006]    In prior art orthodontic brackets  200 , such as the ones described in U.S. Pat. Nos. 5,037,297, 4,941,825, and 4,838,787, it is known to include a curved surface  202  for the wire guide  25  that contacts a wire  40  at a single point under that wire  40 . (See generally FIG. 1.) As shown, the wire  40  extends through the wire guide  25  at a position toward the top of the bracket  200  to provide orthodontic correction according to the Begg light wire technique, to which reference is made in U.S. Pat. No. 5,037,297 at col. 1, lines 31-32.  
           [0007]    Since the surface  202  contacts the wire  40  at only one point  204 , the curved surface  202  permits tooth  206  to tip as it moves into a predetermined orthodontic position in the patient&#39;s mouth. (See, e.g., FIGS. 2 and 3.) The starting angular orientation  208  of the tooth  206 , in relation to the horizontal, is show in FIG. 2, attached. As tooth  206  moves in the patient&#39;s mouth, however, the tooth  206  changes its angular position to an alternative angular position  212 , as shown in FIG. 3.  
           [0008]    Because bracket  200  provides a curved surface  202 , the wire  40  that it contacts is permitted to move in relation to the curved surface  202  as the angular orientation of the tooth changes. Accordingly, regardless of the angular orientation of tooth  206  with respect to the horizontal, the wire  40  can apply whatever orthodontic force is needed to move tooth  206  into a desired position without interfering with the operation of bracket  200 . As illustrated in FIG. 1, the wire  40  is held onto bracket  200  by elastomeric ringlet  210 , for example. Other attachment techniques also may be used, as illustrated in U.S. Pat. Nos. 5,037,297, 4,941,825, and 4,838,787 for example.  
           [0009]    One of the disadvantages of incorporating the curved surface  202  on the bracket  200 , however, is that, in some instances, the curved surface  202  may permit the tooth  206  to over-tip. In other words, where a curved surface  202  is incorporated into the bracket  200 , it is possible to overcorrect the angular orientation of the tooth  206 . If it tips too far, the tooth  206  will require subsequent orthodontic attention to readjust the tooth&#39;s angular orientation. The tooth  206  may tip too far if the patient fails to show-up for his or her regularly-scheduled orthodontic appointments, for example.  
           [0010]    It is, therefore, a failing in the prior art that permits orthodontic overcorrection of the angular orientation of a tooth.  
         SUMMARY OF THE INVENTION  
         [0011]    Accordingly, a need has arisen for an orthodontic bracket that prohibits orthodontic overcorrection. In other words, a need has developed for an orthodontic bracket that provides a stop to prevent the tooth to which the bracket is attached from tipping too far during the orthodontic procedure.  
           [0012]    In addition, because the orthodontic bracket must permit the tooth to change its angular orientation during the orthodontic procedure, a need has arisen for an orthodontic bracket that provides the convenience of a surface that contacts the wire at only one point. (This is known as “one point contact” for the Begg light wire technique.)  
           [0013]    It is an object of the present invention to provide a bracket for orthodontic care that can be used with the Begg light wire technique but that also incorporates a stop to prevent the tooth connected thereto from tipping too far during an orthodontic procedure. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    For a better understanding of the present invention as well as other objects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings. Common reference numerals are used in the various figures to designate the same structure, in which:  
         [0015]    [0015]FIG. 1 is a perspective illustration of a prior art orthodontic bracket;  
         [0016]    [0016]FIG. 2 is a partial cross-sectional view of the bracket shown in FIG. 1, illustrating a starting orientation of the bracket in relation to the wire;  
         [0017]    [0017]FIG. 3 is a partial cross-sectional view of the bracket shown in FIG. 1, illustrating the contact position of the wire to the bracket after the underlying tooth has changed its angular orientation;  
         [0018]    [0018]FIG. 4 is a perspective illustration of the orthodontic bracket of the present invention;  
         [0019]    [0019]FIG. 5 is a partial cross-sectional view of the orthodontic bracket shown in FIG. 4, illustrating a starting orientation of the bracket in relation to the wire;  
         [0020]    [0020]FIG. 6 is a partial cross-sectional view of the orthodontic bracket shown in FIG. 4, illustrating a maximum contact angle between the wire and the bracket; and  
         [0021]    [0021]FIG. 7 is a partial cross-sectional view of a variation of the orthodontic bracket illustrated in FIG. 5 and FIG. 6, illustrating a variation on the maximum contact angle between the wire and the bradket.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    To accomplish the objectives set forth above, the bracket  300  of the present invention (and a variation of bracket  300 , which is labeled as bracket  400 ) includes a surface  302  that has an inverted v-shape. As illustrated in FIGS.  4 - 6 , the inverted v-shaped surface  302  has two generally planar surfaces  304 ,  306  that meet one another at an apex  308 . Wire  40  is positioned in the bracket  300  (in the Begg light wire technique) so that wire  40  is held against apex  308 . Wire  40  may be held in place by any technique known to those skilled in the art. For example, wire  40  may be held against apex  308  by a suitable elastomeric ringlet  310 .  
         [0023]    Since wire  40  is held in place against apex  308 , it advantageously contacts bracket  300  at a single location (like wire  40  contacts curved surface  202  on bracket  200 ). As a result, wire  40  may “rock” in either direction as tooth  206  changes its angular position over time. (See, e.g., FIGS.  2 - 3 .) However, planar surfaces  304 ,  306  provide stop positions to prevent tooth  206  from tipping past a predetermined angular position. In other words, tooth  206  may not tip to an angular position that exceeds the limit provided by either planar surface  304 ,  306 .  
         [0024]    As illustrated in FIG. 6, if tooth  206  tips to point where wire  40  rests on planar surface  306 , it cannot tip further. The planar surface  306 , therefore, acts as a stop (or limit) to prevent the tooth  206  from tipping too far from a predetermined position during a typical orthodontic corrective procedure.  
         [0025]    As illustrated in FIGS. 5 and 6, planar surfaces  304 ,  306  on bracket  300  are disposed in a symmetrical relationship to one another. Specifically, in the preferred embodiment of the present invention, angle  312  (formed between planar surface  304  and side surface  318 ) and angle  314  (formed between planar surface  306  and side surface  318 ) are equal to one another. The intersection of planar surfaces  304 ,  306  forms an angle  310  at apex  308 , as illustrated.  
         [0026]    As would be understood by those skilled in the art, however, angles  312 ,  314  need not be equal to one another. It is contemplated that angles  312 ,  314  may vary from one another so that a greater “tip” angle for tooth  206  may be permitted in one direction over the other. This may be necessary in certain instances where, for example, tooth  206  requires a considerable amount of adjustment during the course of the orthodontic procedure.  
         [0027]    [0027]FIG. 7, which depicts a portion of bracket  400 , is illustrative of the variation of bracket  300  contemplated within the scope of the present invention, as discussed above. In bracket  400 , angle  412  (formed between planar surface  404  and side surface  416 ) is considerably greater than angle  414  (formed between planar surface  406  and side surface  418 ). Planar surface  404 , therefore, is disposed at a greater angular distance from wire  40  than planar surface  406  of v-shaped surface  402 . In this particular example, it is contemplated that tooth  206  will have to be adjusted from its starting angle  420  in a forward tip direction. During the orthodontic procedure, as tooth  206  tips forward, angle  420  will increase until tooth reaches its desired final angle.  
         [0028]    In certain instances, it is contemplated that tooth  206  will require considerable correction to its original angle  420  before the orthodontic procedure is concluded. If bracket  300  were used in such an instance, angle  312  would prevent further forward tipping once wire  40  became parallel with planar surface  304 . In order to continue adjustment of tooth  206  in such a case, bracket  300  would have to be removed and replaced with another bracket  300 . If an extremely large forward tip were required for tooth  206 , the removal and replacement of bracket  300  might have to be repeated several times before the orthodontic procedure is completed.  
         [0029]    However, where bracket  400  is employed, tooth  206  may tip forwardly to a much greater extent than is possible with bracket  300 . Accordingly, for this embodiment of the present invention, it is contemplated that planar surface  404  is disposed a sufficient distance from wire  40  that wire  40  will not come into contact (i.e., become parallel with) planar surface  404  before the orthodontic procedure is complete.  
         [0030]    While one particular example of a variation of bracket  300  is illustrated in FIG. 7, the present invention is meant to encompass any variation thereon. For example, planar surface  406  (in the rearward tip direction) may be disposed so that angle  414  is greater than  412 . This would be necessary where tooth  206  is to be adjusted in the rearward direction. Moreover, the particular angles  310 ,  312 ,  314 ,  410 ,  412 ,  414  selected for brackets  300 ,  400  may be of any suitable magnitude so long as the corrective orthodontic procedure may be employed.  
         [0031]    The foregoing description is meant to be illustrative of the scope of the present invention and is not meant to be limited solely to the embodiments shown and described. To the contrary, those skilled in the art will readily recognize that variations of the embodiments described may be substituted without departing from the scope of the present invention.