Abstract:
The present invention represents a qualitative technique modification of the self-uprighting bracket technique. The present invention overcome the drawbacks of the prior art by providing an orthodontic bracket assembly having a base with rotatable body engaging the archwire and removable plate inserted into the base to retain the archwire. In addition, the removable plate can allow or prevent the rotation of the rotatable body depending on the different stages of the treatment.

Description:
FIELD OF THE INVENTION 
     This invention relates to a new and improved orthodontic bracket assembly for use in edgewise wire techniques to facilitate tipping movement of a tooth and sliding of the bracket assembly along an archwire, including structure to minimize frictional resistance, thereby reducing the time of completing the movement to the desired location along the arch, and enhancing the health and comfort of the patient. 
     DESCRIPTION OF RELATED ART 
     As known in the dental art, in order to identify specific locations on a tooth, the tooth is divided into different surfaces and each surface has a specific name. The surfaces are named according to the direction in which they face. The surfaces of teeth are as follows. A “lingual” surface refers to the surface of a tooth facing the tongue. A “facial” surface refers to the surface of a tooth facing the cheeks or lips. This surface (“facial”) can also be known as a “labial” surface, the surface of an anterior tooth facing the lips, and a “buccal” surface, the surface of a posterior tooth facing the cheeks. A “proximal” surface refers to the surface of a tooth that faces a neighboring tooth&#39;s surface; each tooth has two proximal surfaces. A “mesial” surface refers to the surface of a tooth that is closest to the midline (middle) of the face. A “distal” surface refers to the surface of a tooth that faces away from the midline of the face. An “occlusal” surface refers to the chewing surface of posterior teeth. An “incisal ridge (or edge)” refers to the biting edge of anterior teeth. 
     Orthodontic brackets are secured to a patient&#39;s teeth for use to selectively straighten the patient&#39;s teeth. One type of orthodontic bracket known in the art includes a base having a slot formed thereon. The slot is configured to receive an archwire that extends between different teeth. A stopping means is removably attached to the base for use in securing the archwire to the base. Examples of these brackets are described in Peter C. Kesling, Dynamics of the Tip-edge Bracket, Am. J. Orthod Dentofac Orthop, 1989, 96:16-25, and Peter C. Kesling et al., treatment with Tip-Edge Brackets and Differential Tooth Treatment, Am. J. Orthod Dentofac Orthop, 1991, Vol. 99, No. 5, pages 387-401, and U.S. Pat. No. 4,859,179. 
     To reach Class I occlusion, the prior art orthodontic brackets take an extended period of time, anchorage and springs are usually required. 
     The prior straight archwire technique has several drawbacks. As the bracket slot is straight, the forces to move teeth are excessive (there is no tipping movement but sliding with a large amount of friction). This means that there will be iatrogenic or undesired movements of the teeth from where forces are applied to where the physician wants them to act. To prevent this undesired movement, it becomes necessary to anchor the teeth from where forces are applied by means of additional uncomfortable devices such as transpalatal bars or extra-oral orthodontic headgear. In the present technique, these anchor devices are not necessary as teeth tip without friction to its final position. It is from this final position that the non-engaging lid changes for the engaging one to upright the teeth roots. 
     In the tip-edge technique developed by Peter Kesling, non-friction movement is possible because of tip-edge slot that allows for dental tipping, but in its technique additional springs are used to upright the teeth roots. In the present invention, the bracket upright force comes from the archwire which is deflected when the engaging lid is attached to the bracket in the final stage of treatment. This force is much more constant in strength throughout the treatment. In addition, different archwires sizes can be used in this final period to produce a variety of forces in comparison to a single type of spring that can be used in the tip-edge technique. 
     SUMMARY OF THE INVENTION 
     The present invention represents a qualitative technique modification of the self-uprighting bracket technique. The present invention overcome the drawbacks of the prior art by providing an orthodontic bracket assembly having a base with a rotatable body engaging the archwire and removable plate inserted into the base to retain the archwire. In addition, the removable plate can allow or prevent the rotation of the rotatable body depending on the different stages of the treatment. 
     An additional object of the present invention is to provide a bracket assembly in which the each of the holding members on the upper surface of the base comprises a vertical portion and a top horizontal flange or rim to define a recess for receiving the rotatable body. 
     A further object of the present invention is to provide a bracket assembly wherein the rotatable body comprises a circular base member; and an upper member comprised of two generally half-circular parts to form a slot between the half-circular parts for engaging the wire. 
     A still further object of the present invention is to provide a bracket assembly with a generally E-shaped removable plate to retain the archwire in the rotatable body and to allow or prevent the rotation of the rotatable body depending on the stages of the teeth treatment. 
     The present invention also provides a method of making the bracket assembly as well a method of using the bracket assembly in teeth alignment and dental treatment. 
     The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the embodiments of the orthodontic bracket assembly in use on teeth of a patient according to the present invention. 
         FIG. 2  is a perspective view of one embodiment of the orthodontic bracket assembly according to the present invention, where the removable plate is inserted. 
         FIG. 3  is a top plan view of one embodiment of the orthodontic bracket assembly according to the present invention, wherein the removable plate is inserted. 
         FIG. 4  is a front elevational view of one embodiment of the orthodontic bracket assembly according to the present invention, wherein the removable plate is inserted. 
         FIG. 5  is a rear elevational view of one embodiment of the orthodontic bracket assembly according to the present invention, wherein the removable plate is inserted. 
         FIG. 6  is a left elevational view of one embodiment of the orthodontic bracket assembly according to the present invention, wherein the removable plate is inserted. The right elevational view is a mirror image. 
         FIG. 7  is a perspective view of one embodiment of the orthodontic bracket assembly according to the present invention, wherein the removable plate is not inserted. 
         FIG. 8  is a cross-sectional view of the orthodontic bracket assembly according to the present invention along the line  8 - 8  in  FIG. 7 . 
         FIG. 9  is a cross-sectional view of the orthodontic bracket assembly according to the present invention along the line  9 - 9  in  FIG. 8 . 
         FIG. 10  is a cross-sectional view of the orthodontic bracket assembly according to the present invention along the line  10 - 10  in  FIG. 8 . 
         FIG. 11  is a perspective view of a base of the orthodontic bracket assembly according to the present invention, wherein the intermediate layer comprised of two separate parts spaced apart. 
         FIG. 12  is a perspective view of a base of the orthodontic bracket assembly according to the present invention, wherein two parts of the intermediate layer are welded together into an integral part. 
         FIG. 13  is a perspective view of a rotatable body of the orthodontic bracket assembly according to the present invention. 
         FIG. 14  is a perspective view of a removable plate (with a latch) of the orthodontic bracket assembly according to the present invention. 
         FIG. 15  is a perspective view of a removable plate (without a latch) of the orthodontic bracket assembly according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although the invention will be described next in connection with certain embodiments, the invention is not limited to practice in any one specific type of orthodontic bracket assembly. The description of the embodiments of the invention is intended to cover all alternatives, modifications, and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims. In particular, those skilled in the art will recognize that the components of the embodiments of the invention described herein could be arranged in multiple different ways. 
     Referring now to the drawings and particularly to the embodiments shown in the drawings, the orthodontic bracket assembly  11  comprises a base  20  adapted to be mounted on a tooth; a rotatable body  30  mounted on the base  20  for rotation movement with respect to the base  20  and comprising a slot  34 ,  35  adapted to engage a wire; and a removable plate  40  adapted to be inserted into and retained within the base  20  to secure the wire in the slot  34 ,  35 . 
     The base  20  comprises a bottom surface  202 , an upper surface  201  generally parallel to the bottom surface  202  and surrounding peripheral walls  203 ,  204 ,  205 ,  206  connecting the upper surface  201  and the bottom surface  202 . Preferably, the bottom and upper surfaces  201 ,  202  are each in generally square or rectangular shape. There are four surrounding walls  203 ,  204 ,  205  (not shown),  206  (not shown) and opposing walls ( 203  and  205 ,  204  and  206 ) are parallel to each other. The bottom surface  202  of the base  20  is adapted to be mounted on or attached to a tooth surface. The possible means of mounting or attachment include adhesion by adhesives or other methods. 
     Preferably, four hooks  12 ,  13 ,  14 ,  15  in the shape of a nail or bolt are attached to or mounted on the four corners of the upper surface  201  of the base  20 . The hooks can be used to hold elastic bands. An intermediate layer  25  that is generally rectangular or square shape may optionally be mounted on the upper surface  201 . Alternatively, an embodiment of the present invention may not include the intermediate layer  25 . The intermediate layer  25  are located at the central area of the upper surface  201  and no larger than the area defined by the four hooks  12 ,  13 ,  14 ,  15 . 
     Preferably, four holding members  16 ,  17 ,  18 ,  19  for holding a rotatable body  30  are located near the corners of the intermediate layer  25 . Alternatively, the four holding members  16 ,  17 ,  18 ,  19  may directly mounted on or attached to the upper surface  201  of the base  20  without the intermediate layer  25 . The four holding members  16 ,  17 ,  18 ,  19  are positioned to form a generally square or rectangular shape with each holding member at each corner of the generally square or rectangular shape, respectively. The four holding members  16 ,  17 ,  18 ,  19  may be integral with the upper surface  201  or the intermediate layer  25 , or alternatively, can be separate elements bonded to the upper surface  201  or the intermediate layer  25 . 
     Preferably, the four holding members  16 ,  17 ,  18 ,  19  extend above the upper surface  201  and the intermediate layer  25  of the base  20 . Each of the holding members  16 ,  17 ,  18 ,  19  comprises a vertical portion  161 ,  171 ,  181 ,  191  and a top horizontal flange or rim  162 ,  172 ,  182 ,  192 . For example, as shown in  FIG. 11 , the holding member  16  comprises a vertical portion  161  and a top horizontal flange or rim  162 , The vertical portion  161  mounted on or integral with the upper surface  201  and the intermediate layer  25  of the base  20  and extends above the upper surface  201  and the intermediate layer  25  of the base  20  in a direction away from the base  20 . The top horizontal flange or rim  162  is in connection with or integral with the vertical portion  161  at an end of the vertical portion  161  distal to the base  20 . The top horizontal flange or rim  162  is parallel to the upper surface  201  of the base  20  and generally vertical to the vertical portion  161 . The flange or rim is preferably a generally square flange or rim, in particularly, in a generally cuboid shape. 
     Each of the four holding members  16 ,  17 ,  18 ,  19  comprises a recess  165 ,  175 ,  185 ,  195  for holding the rotatable body  30  and a slit  164 ,  174 ,  184 ,  194  for receiving the removable plate  40 . The recess  165 ,  175 ,  185 ,  195  is formed between the upper surface  201  of the base  20  or the intermediate layer  25  and the top horizontal flange or rims  162 ,  172 ,  182 ,  192  of the holding members  16 ,  17 ,  18 ,  19 . The recess  165 ,  175 ,  185 ,  195  is preferably in the shape of steps  163  of a staircase with the lower or starting step based on the upper surface  201  or intermediate layer  25  of the base  20 . This means that the vertical portion and top horizontal flange or rim of the each holding member are in upside down staircase shape complementary to the recess, such that the starting step begins at the square flange of the top horizontal flange or rim. The recess  165 ,  175 ,  185 ,  195  allows for inserting and retaining therein a part of the rotatable body  30  by the top horizontal flange or rim of each holding member through the square flange or rim. The four holding members  16 ,  17 ,  18 ,  19  together hold the rotatable body  30  in place by preventing it from moving away from the base  20  and at the same time allowing the rotatable body  30  to rotate. The rotatable body  30  is preferably in a circular shape. The recess  165 ,  175 ,  185 ,  195  and the holding members  16 ,  17 ,  18 ,  19  are complementary to the shape of the rotatable body  30 . 
     As stated above, each of the holding members  16 ,  17 ,  18 ,  19  comprises a slit  164 ,  174 ,  184 ,  194  for receiving and retaining a removable plate  40 . The removable plate  40  is inserted into all four holding members  16 ,  17 ,  18 ,  19  when an archwire is inserted into the slot  34 ,  35  of the rotatable body  30 . The shapes of the slits  164 ,  174 ,  184 ,  194  are complementary to parts of the removable plate  40  that is inserted into the holding members  16 ,  17 ,  18 ,  19 . As shown in  FIGS. 14-15 , the removable plate  40  is in generally an E-shape and comprises a backbone part  41  in connection with a middle leg  42  and two outer legs  43 ,  44  on each side of the middle leg  42 , all legs  42 ,  43 ,  44  being generally vertical to the backbone part  41 . Two adjacent holding members  16 ,  19  each comprises a slit  164 ,  194  that is able to receive at least a part of one of the outer legs  43 ,  44  of the E-shaped removable plate  40 . The other two adjacent holding members  17 ,  18  each comprises a slit  174 ,  184  that is able to receive at least a part of the backbone  41  and a part of the outer leg  43 ,  44  in connection with the backbone  41  of the E-shaped removable plate  40 . The slits  164 ,  174 ,  184 ,  194  are generally located at the top horizontal flange or rims  162 ,  172 ,  182 ,  192  of the holding members  16 ,  17 ,  18 ,  19 , in particular, the square flanges or rims of the holder members. The vertical distance between the slit  164 ,  174 ,  184 ,  194  and the upper surface  201  of the base  20  is larger than the vertical distance between the top of the recess  165 ,  175 ,  185 ,  195  (the bottom surface of the square flange or rim  162 ,  172 ,  182 ,  192  facing the upper surface  201  of the base  20 ) and the upper surface  201  of the base  20 . 
     The bracket assembly  11  of the present invention can be made according to the following steps. The base  20 , the intermediate layer  25  and the holding members  16 ,  17 ,  18 ,  19  are made from two symmetric pieces. For example, each piece may include half base, half intermediate layer, two holding members and two hooks. After a part of the rotatable body  30  is inserted into the recess  165 ,  175  of two holding members  16 ,  17  of one of the symmetric pieces, the other symmetric piece is attached to the first symmetric piece such that another part of the rotatable body  30  is also inserted into the recess  185 ,  195  of other two holding members  18 ,  19  of the other symmetric piece. The two symmetric pieces are then joined by, for example, welding, along the line  400 . 
     The rotatable body  30  is adapted to engage an orthodontic wire and is preferably in a generally circular shape. The rotatable body  30  comprises a circular base member  31  and an upper member  32 ,  33  mounted on the top of the circular base member  31 . The upper member  32 ,  33  preferably comprises two generally half-circular part forming an upper circle. The diameter of the upper circular  32 ,  33  is shorter than the diameter of the circular base member  31 . The upper circle  32 ,  33  and the circular base member  31  are preferably concentric. The two ends  36 ,  38  of one of the half-circular part  32  space apart from and do not contact the two ends  37 ,  39  of the other of the half circular part  33 , such that a slot  34 ,  35  is formed for receiving and retaining therein an orthodontic wire between the ends  36 ,  37 ,  38 ,  39  of the half-circular parts  32 ,  33 . The half-circular part  32 ,  33  is preferably sectionally square or rectangular shaped. 
     In addition, one half-circular part  33  preferably comprises a groove  300  for receiving a latch  45  of the removable plate  40  such that the rotatable body  30  is prevented from rotating when such latch  45  is inserted into the half-circular part  33  of the rotatable body  30 . Such groove  300  is preferably located in a middle position of the half-circular part  33  facing away from the center of the circle formed by the half-circular parts  32 ,  33 . 
     The structure of the removable plate  40  is explained as follows (see  FIGS. 14-15 ). The removable plate  40  is in generally an E-shape and comprises a backbone part  41  in connection with three legs  42 ,  43 ,  44  that are parallel to one another and generally vertical to the backbone part  41 . The backbone part  41  is preferably an elongated rectangular strip. A first leg  43  and a second leg  44  connect with the two ends of the backbone part  41 , and a middle leg  42  in connection with about the middle point of the backbone part  41 . The middle leg  42  can be shorter than the first leg  43  and the second leg  44 . The backbone part  41 , the first leg  43 , the second leg  44  and the middle leg  42  are all in the same plane. 
     According to an alternative embodiment of the removable plate  40  as shown in  FIG. 15 , a latch  45  is located about the middle point of backbone part  41  of the removable plate  40 . Preferably, the latch  45  is in the shape of cuboid or cube. The latch  45  can be inserted into the groove  300  on one of the half-circular part  33  of the rotatable body  30 . 
     The components and parts of the bracket can be made with appropriate materials. For example, all bracket components are made of stainless steel except for the removable the removable plate that can be made of nickel titanium, which is an elastic metal. 
     This new self-ligating bracket technique acts similar to the tip-edge bracket technique in first treatment stages. As the tip-edge technique, it is a differential tooth movement edgewise technique. 
     In first treatment stages, the goal is to reach a class I occlusion without overbite or overjet and with teeth alignment. Thus, in this stage, the bracket will be used with the removable plate  40  that allows free movement of the rotational part, as shown in  FIG. 14 . The teeth will move mesiodistally by crown tipping making the need for anchorage minimum as opposed the classic edgewise technique designed by E. Angle. Due to the rotation of the circular body of the bracket during teeth movement, there is no friction between the archwise and the bracket and therefore no need for anchorage. 
     In this treatment as descried above, it takes much less time to reach class I occlusion than prior art, such as non-frictional technique, i.e. the tip-edge technique, and no anchorage compared to those that are based on tooth bodily controlled movement throughout the treatment. Once class I is reached, the latch bearing removable plate as shown in  FIG. 15  is coupled to the bracket. This fixes the rotatable body  30  in a predetermined position in a way that the archwire is deflected. This deflection will transmit an uprighting force to the teeth. 
     When put to use, the bracket assembly of the present invention is attached to dental surface, with acid etching of dental surface and photopolymerization of composite material. 
     An example of the teeth alignment method of the present invention may comprise the following steps: 
     attaching the bases of the bracket assemblies to a plurality of teeth, respectively; 
     inserting a wire through the slots of the rotatable bodies of the bracket assemblies, respectively; 
     inserting a first group of removable plates into the bases of the bracket assemblies, respectively, wherein the first group of removable plates allow for free rotation of the rotatable bodies; 
     determining whether class I occlusion is reached; 
     removing the first group of the removable plates from the bases of the bracket assemblies, respectively; 
     inserting the second group of removable plates into the bases of the bracket assemblies, respectively, wherein the second group of removable plates prevent the free rotation of the rotatable bodies by latches on the second group of removable plates inserted into corresponding grooves of the rotatable bodies; and 
     determining whether desired teeth alignment is achieved. 
     The great advantage of the present invention over others is that it is a combined self-ligating self-uprighting technique where all forces come from the archwire and there is no need for a spring. 
     While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the inventors to restrict or in any way limit the scope of the appended claims to such detail. Thus, additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in any combination depending on the needs and preferences of the user.