Abstract:
A tray for use in bonding orthodontic appliances to selected teeth of a patient is disclosed. The tray includes an outer shell having wall sections extending over facial, lingual, and occlusal surfaces of the selected teeth to form a channel including tooth cavities having a configuration matching and arranged for receiving the selected teeth. A matrix is bonded to the inner surface of the outer shell and is contoured to complement the facial or lingual surface of the teeth. A stabilization member extends from the outer shell and includes an inside surface contoured to complement at least a portion of the facial surface of a tooth located adjacent the selected teeth. Orthodontic appliances are detachably connected to the matrix, wherein each appliance includes a base for bonding the appliance to a tooth.

Description:
FIELD OF THE INVENTION 
     This invention relates to method and apparatus for bonding orthodontic appliances such as brackets to a patient&#39;s teeth. The present invention specifically relates to an indirect bonding tray including stabilization features. 
     BACKGROUND OF THE INVENTION 
     Orthodontic treatment involves movement of malpositioned teeth to desired locations in the oral cavity. Orthodontic treatment can improve the patient&#39;s facial appearance, especially in instances where the teeth are noticeably crooked or where the jaws are out of alignment with each other. Orthodontic treatment can also enhance the function of the teeth by providing better occlusion during mastication. 
     One common type of orthodontic treatment involves the use of tiny, slotted appliances known as brackets. The brackets are fixed to the patient&#39;s teeth and an arch wire is placed in the slot of each bracket. The arch wire forms a track to guide movement of teeth to desired locations. 
     The ends of orthodontic arch wires are often connected to small appliances known as buccal tubes that are, in turn, secured to the patient&#39;s molar teeth. In many instances, a set of brackets, buccal tubes and an arch wire is provided for each of the patient&#39;s upper and lower dental arches. The brackets, buccal tubes and arch wires are commonly referred to collectively as “braces”. 
     In many types of orthodontic techniques, the precise position of the appliances on the teeth is an important factor for helping to ensure that the teeth move to their intended final positions. In general, orthodontic appliances that are adapted to be adhesively bonded to the patient&#39;s teeth are placed and connected to the teeth by either one of two techniques: a direct bonding technique, or an indirect bonding technique. 
     In the direct bonding technique, the appliance and adhesive are grasped with a pair of tweezers or other hand instrument and placed by the practitioner on the surface of the tooth in an approximate desired location. Next, the appliance is shifted along the surface of the tooth as needed until the practitioner is satisfied with its position. Once the appliance is in its precise, intended location, the appliance is pressed firmly onto the tooth to seat the appliance in the adhesive. Excess adhesive in areas adjacent the base of the appliance is removed, and the adhesive is then allowed to cure and fix the appliance firmly in place. While the direct bonding technique described above is in widespread use and is considered satisfactory by many, there are shortcomings that are inherent with this technique. For example, access to surfaces of malposed teeth may be difficult. In some instances, and particularly in connection with posterior teeth, the practitioner may have difficulty seeing the precise position of the bracket relative to the tooth surface. Additionally, the appliance may be unintentionally dislodged from its intended location during the time that the excess adhesive is being removed adjacent the base of the appliance. 
     Indirect bonding techniques avoid many of the problems associated with direct bonding. In general, indirect bonding techniques known in the past have involved the use of a placement device or transfer apparatus having a shape that matches the configuration of one or more of the patient&#39;s teeth in the dental arch. One type of placement device or transfer apparatus is often called a “transfer tray” and typically has a cavity for receiving a number of teeth simultaneously. A set of appliances such as brackets are releasably connected to the tray at certain, predetermined locations. 
     During the use of an orthodontic transfer apparatus for indirect bonding, an adhesive is typically applied to the base of each appliance by the orthodontist or a staff member. The device is then placed over the patient&#39;s teeth and remains in place until such time as the adhesive hardens. Next, the apparatus is detached from the teeth as well as from the appliances, with the result that all of the appliances previously connected to the apparatus are now bonded to respective teeth at their intended, predetermined locations. 
     In more detail, one method of indirect bonding of orthodontic appliances using the transfer tray described above includes the steps of taking an impression of each of the patient&#39;s dental arches and then making a replica plaster or “stone” model from each impression. Next, the appliances are bonded to the stone models at desired locations. Optionally, the brackets may be adhesive precoated brackets. 
     The transfer tray is then made by placing a matrix material over the model as well as over the appliances placed in the model. For example, a plastic sheet matrix material may be held by a frame and exposed to radiant heat. Once the plastic sheet material has softened, it is placed over the model and the appliances. Air in the space between the sheet material and the model is then evacuated, and the plastic sheet material assumes a configuration that precisely matches the shape of the replica teeth of the stone model and attached appliances. The plastic sheet matrix material is then allowed to cool and harden to form a tray. The tray and the appliances (which are embedded in an interior wall of the tray) are then detached from the stone model. If the cured adhesive that was used to bond the appliances to the stone model remains on the base of the appliances after detachment from the stone model, the adhesive serves as a “custom” base having a concave contour that precisely replicates the convex contour of the previous attachment location of the stone model, as well as the convex configuration of the intended mounting location of the appliances on the patient&#39;s teeth. 
     Once the patient has returned to the practitioner&#39;s office, a quantity of adhesive is placed on the base of each appliance, and the tray with the embedded appliances is then placed over the matching portions of the patient&#39;s dental arch. Since the configuration of the interior of the tray closely matches the respective portions of the patient&#39;s dental arch, each appliance is ultimately positioned on the patient&#39;s teeth at precisely the same location that corresponds to the previous location of the same appliance on the stone model. 
     Indirect bonding techniques offer a number of advantages over direct bonding techniques. For one thing, and as indicated above, it is possible to bond a plurality of appliances to a patient&#39;s dental arch simultaneously, thereby avoiding the need to bond each appliance in individual fashion. In addition, the transfer apparatus helps to locate the appliances in their proper, intended positions such that adjustment of each appliance on the surface of the tooth before bonding is avoided. The increased placement accuracy of the appliances that is often afforded by indirect bonding techniques helps ensure that the patient&#39;s teeth are moved to their proper, intended positions at the conclusion of treatment. 
     In recent years, many improvements have been made in the field of indirect bonding. However, there is a continuing need in the art to improve methods for fabricating the transfer apparatus or transfer tray. For example, improper fit of the transfer tray over the patient&#39;s teeth is a common problem. For example, when a practitioner utilizes an indirect bonding technique, it is critical that the practitioner be able to precisely place the transfer tray over matching surfaces of the patient&#39;s teeth. An improperly fitted transfer tray may result in appliances being bonded to locations on the patient&#39;s teeth that are imprecise and do not correspond to the previous location of the same appliance on the stone model. As a result, malpositioned teeth may move to unintended positions during the treatment program. 
     Although the transfer tray is fabricated to match the surfaces of the patient&#39;s teeth, as is often the case, the transfer tray may be somewhat unstable, loose, or inaccurate. Such instability can result from several factors. For example, inaccuracies may arise during the steps leading up to the fabrication of the transfer tray. Inaccuracies may arise during fabrication of the impression of the patient&#39;s teeth, or during the fabrication of the stone model based upon each impression. Inaccuracies may also arise during bonding of the appliances to the stone model at desired locations. Additionally, inaccuracies may arise due to the fact that the transfer tray is customarily fabricated of a material that is insufficiently rigid. Due to any one or a combination of the foregoing factors, a certain amount of instability, “wiggle”, or “play” often arises when the transfer tray is placed over matching surfaces of the patient&#39;s teeth during the indirect bonding process. The potential for such instability increases, especially when the transfer tray is arranged for placement over only a small number of teeth, e.g., two or three teeth. 
     For the foregoing reasons, it is desirable to increase placement accuracy of the transfer tray over matching surfaces of the patient&#39;s teeth during the indirect bonding procedure. It would be desirable to provide a transfer tray that includes a feature or mechanism that would provide stabilization and enable the practitioner to visually assess or determine whether the transfer tray has been placed or seated onto the patient&#39;s teeth in the position as originally planned and intended. Other than its surfaces that match a patient&#39;s teeth, currently available transfer trays (made for one or multiple teeth) do not provide the practitioner with such a feature or mechanism. 
     SUMMARY OF THE INVENTION 
     A tray for use in bonding orthodontic appliances to selected teeth of a patient is disclosed. The tray includes an outer shell having wall sections extending over facial, lingual, and occlusal surfaces of the selected teeth to form a channel including tooth cavities having a configuration matching and arranged for receiving the selected teeth. A matrix is bonded to the inner surface of the outer shell and has an inner surface, a portion of which is contoured to complement the facial surface of the selected teeth. Alternatively, a portion of the matrix inner surface may be conformed to complement the lingual surface of selected teeth. A stabilization member extends from the outer shell and includes an inside surface contoured to complement at least a portion of the facial surface of a tooth located adjacent the selected teeth. Orthodontic appliances are detachably connected to the matrix, wherein each appliance includes a base for bonding the appliance to a tooth. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of the orthodontic indirect bonding tray including stabilization features of the present invention applied to teeth of the upper dental arch of a patient, the upper dental arch being rotated one-hundred eighty degrees to illustrate the occlusal surfaces of the teeth located therein; 
         FIG. 2  is a view of the upper dental arch of  FIG. 1  including a cross-sectional view of the orthodontic indirect bonding tray of the present invention, showing teeth in phantom; 
         FIG. 3  is a perspective view of the orthodontic indirect bonding tray including stabilization features of the present invention; 
         FIG. 4  is another isometric view of the orthodontic indirect bonding tray including stabilization features of the present invention; and, 
         FIG. 5  is a cross-sectional view of the orthodontic indirect bonding tray including stabilization features of the present invention, shown mounted over teeth. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now in greater detail to the drawings in which like numerals represent like components throughout the several views, there is shown in  FIGS. 1-5  an embodiment of the orthodontic indirect bonding tray including stabilization features of the present invention which is broadly designated by the numeral  20 . As best shown in  FIGS. 1 and 2 , the bonding tray  20  is shown positioned over several teeth  14  of the upper jaw  18 , or maxilla, of an orthodontic patient, the teeth  14  requiring corrective orthodontic alignment.  FIG. 1  illustrates the upper dental arch rotated one-hundred eighty degrees to illustrate the occlusal surfaces of the teeth located therein. Although the figures illustrate the indirect bonding tray of the present invention positioned over teeth of the upper jaw, it should be understood that it is within the scope of the present invention that the bonding tray  20  could be positioned over teeth of the lower jaw. 
     The tray  20  includes a channel  22  ( FIG. 4 ) comprising a plurality, e.g. three, tooth cavities for receiving selected teeth  14  within a patient&#39;s dental arch. In the exemplary tray  20  shown in the drawings, the channel  22  is adapted to receive teeth  14  located in a patient&#39;s upper dental arch, although it should be understood in this regard that as an alternative, the tray  20  may be constructed to receive teeth  14  located in the patient&#39;s lower dental arch (not shown). 
     The tray  20  also includes a number of orthodontic appliances  28  that are detachably connected to the tray  20 . In  FIGS. 1-5 , the exemplary illustrated orthodontic appliance  28  is an orthodontic bracket, although other appliances are also possible. Examples of other suitable appliances include buccal tubes, buttons, formed “bumps” made, e.g., of composite material, or any other metal or non-metal “handle” or other structure connected to the teeth  14  that provides an attachment point for a force member such as a wire, aligner tray, polymeric strip, elastomeric band or chain, or any combination of the foregoing. 
     Referring now to  FIG. 5 , the tray  20  may be constructed according to any one of a variety of known techniques. In the example shown in  FIG. 5 , the tray  20  is formed of an inner matrix  26 , formed of a relatively flexible material, and an outer shell  30 , which is formed of a material that is relatively hard in comparison to the inner matrix  26 . 
     The inner matrix  26  has a relatively low viscosity before hardening so that intimate contact between the inner matrix  26  and each appliance  28 , e.g., orthodontic bracket, is assured. As best shown in  FIGS. 1, 2 and 5 , three appliances  28  are shown to be in contact with the inner matrix  26 , although it should be understood in this regard that as an alternative, the tray  20  may be constructed to receive a greater or fewer number of appliances  28 . As best shown in  FIG. 5 , the relatively soft inner matrix  26  is shown as penetrating the various recesses, cavities and other structural features of each appliance  28  so that a secure connection between the appliances  28  and the inner matrix  26  can be established. In  FIG. 5 , the inner matrix  26  is shown as contacting the facial surface of the tooth  14 . The inner matrix  26  also includes a contour that matches and makes contact with the facial surface  14   c  of the patient&#39;s teeth  14  in the area surrounding the appliance  28 . 
     It should be understood that alternatively, in the event appliances  28  are to be attached to the lingual surface of teeth  14 , then the inner matrix  26  could be contoured to match and arranged to contact the lingual surface  14   a  of the teeth  14 , as opposed to the facial surface. In other words, depending upon whether appliances  28  are to be attached to the facial  14   c  or lingual  14   a  surfaces of teeth  14  will dictate whether the inner matrix  26  is to be located adjacent the facial or lingual surface of the teeth  14 . Any suitable material may be utilized for the inner matrix  26  so long as it is relatively clear to permit a curing light to pass through the inner matrix  26  to enable curing of the adhesive for bonding the appliances  28  to the surfaces of the teeth  14 . An example of a suitable material for the inner matrix  26  is Essix® Bleach Tray and Model Duplication Material (1.5 mm thickness) available from Dentsply Raintree Essix, located in Metarie, La. 
     The relatively hard outer shell  30  includes a contour that precisely matches the surfaces of the tooth  14  where the outer shell  30  contacts the tooth  14 , e.g., the lingual  14   a  and occlusal  14   b  surfaces of the tooth  14 . For example, as shown in  FIG. 5 , the outer shell  30  directly contacts the lingual  14   a  and occlusal  14   b  surfaces, as well as surrounds the inner matrix  26  over the facial surface  14   c  of the patient&#39;s teeth  14 . As shown in  FIG. 5 , the inner matrix  26  directly contacts the facial  14   c  surface of the tooth  14 . Although not shown in the drawings, in the event appliances  28  are to be attached to the lingual surface  14   a  of teeth  14 , then the outer shell  30  would include a contour that precisely matches the facial  14   c  and occlusal  14   b  surfaces of the tooth  14 , and the outer shell would directly contact those tooth surfaces. The outer shell  30  would surround the inner matrix  26  over the lingual surface  14   a  of the patient&#39;s teeth  14 , the inner matrix  26  being in direct contact with this tooth surface. 
     Preferably, the outer shell  30  chemically bonds to the inner matrix  26  with a relatively high bond strength. Any suitable material may be utilized for the outer shell  30  so long as it is relatively clear to permit a curing light to pass through the outer shell  30  to enable curing of the adhesive for attaching the appliances  28  to the surfaces of the teeth  14 . An example of a suitable material for the relatively hard outer shell  30  is Essix A+® Plastic, also available from Dentsply Raintree Essix, located in Metarie, La. 
     For example, the relatively hard surface of the outer shell  30  directly contacts the patient&#39;s teeth on the lingual  14   a  and occlusal  14   b  surfaces of the teeth  14 , while the relatively soft and flexible surface of the inner matrix  26  is limited to direct contact with the facial surface  14   c  of the teeth in the vicinity where it penetrates the appliances  28 . By maximizing the amount of relatively hard outer shell  30  directly contacting the teeth  14  and minimizing the amount of relatively soft and flexible inner matrix  26  directly contacting the teeth  14 , an improved mating fit of the tray  20  with the patient&#39;s teeth  14  may be obtained such that little, if any, tolerance or “slop” is present and relative movement between the tray  20  and the teeth  14  of the dental arch is substantially eliminated. In this manner, the transfer tray  20  is sufficiently rigid in the areas where it makes direct contact with the teeth  14 . Such a construction will reduce instability, “wiggle”, or “play” that often arises when the transfer tray is placed over matching surfaces of the patient&#39;s teeth during the indirect bonding process. In this manner, heightened assurance is provided to the practitioner that each appliance  28  will be positioned on the patient&#39;s teeth at precisely the same location that corresponds to the previous location of the same appliance on the stone model. 
     Moreover, as an additional feature to address the problem of inaccurate placement of the orthodontic appliance onto a patient&#39;s tooth, the tray  20  of the present invention is provided with a stabilization member  32  which is shown in  FIGS. 1-4  as extending in the mesial direction from the anterior end of the tray  20  to a tooth  34  located adjacent the teeth  14  to which appliances  28  are to be applied. Although  FIGS. 1-4  illustrate the stabilization member  32  extending in a mesial direction from the anterior end of the tray  20 , it should be understood that the stabilization member  32  may extend in the distal direction from the posterior end of the tray  20  to an adjacent tooth  34 , also for the purpose of increasing the accuracy of placement of the orthodontic appliance onto a patient&#39;s tooth  14 . The stabilization member  32  provides an extra point of contact to adjacent structure, e.g. an adjacent tooth  34 , and also provides a visual confirmation to the practitioner that a correct fit of the tray  20  that was originally planned for has been achieved. Such visual confirmation is especially important in cases where the tray  20  is arranged for placement over posterior teeth where the practitioner may have difficulty seeing the precise position of the bracket  28  relative to the tooth surface. 
     The inner surface of the stabilization member  32  is precisely contoured to the surface of the adjacent tooth  34  and provides a visual indicator of correct tray placement. As best shown in  FIGS. 1 and 2 , the stabilization member  32  is precisely contoured to match and positioned to contact the facial surface of the adjacent tooth  34 . Although  FIGS. 1 and 2  illustrate the stabilization member  32  as being positioned and contoured to contact the facial surface of the adjacent tooth, it should be understood that the stabilization member  32  may also be precisely contoured to match and positioned to contact the occlusal surface, or the lingual surface of the adjacent tooth  34 . Alternatively, the stabilization member  32  could be positioned and contoured to contact two surfaces of the adjacent tooth, e.g., the facial and occlusal surfaces, or the lingual and occlusal surfaces of the adjacent tooth  34 . 
     The stabilization member  32  may be formed of any suitable material, e.g., acrylic, acetate, resin, plastic, metal, silicone, polyvinyl, or materials derived from stereolitographic processes, among others. The stabilization member  32  may also be formed of the material used to form the outer shell  30 . The stabilization member  32  may be transparent or translucent. The stabilization member  32  may be integral with the tray  20 , or a separate component that is attached to the tray  20 , by any suitable means. 
     It is understood that the orthodontic indirect bonding tray including stabilization features of the present invention and its constituent parts described herein is an exemplary indication of a preferred embodiment of the invention, and is given by way of illustration only. In other words, the concept of the present invention may be readily applied to a variety of preferred embodiments, including those disclosed herein. While the invention has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.