Rapid prototyped transfer tray for orthodontic appliances

Abstract

The present invention is directed to computer-implemented methods of making a transfer tray using rapid prototyping techniques, where the gingival edge of the tray is defined to intersect with at least one receptacle for receiving an orthodontic appliance. This tray configuration helps to minimize the travel distance of the tray when placing the tray over a patient's teeth, while also preserving a high degree of mechanical retention for retaining the appliance until such time that the appliance is bonded to the tooth. Other aspects of the tray and associated methods of bonding are directed to a frangible web that extends over the gingival portion of the receptacle and fractures to facilitate tray removal after bonding.

1 . A method of making a transfer tray for bonding an orthodontic appliance comprising:
 obtaining a virtual model of a patient's dental structure;   determining a desired location for a virtual orthodontic appliance on the model;   providing a virtual receptacle sufficient to releasable retain the appliance at the desired location, wherein the virtual receptacle has a configuration that matches at least a portion of the appliance;   deriving a virtual tray body extending across at least a portion of the model and at least a portion of the receptacle remote from the model, wherein the act of deriving a virtual tray body includes the act of defining a gingival edge of the tray body that intersects the virtual receptacle; and   forming the transfer tray by rapid prototyping, wherein the transfer tray includes a physical tray body and a physical receptacle that correspond to the virtual tray body and virtual receptacle respectively.   
     
     
         2 . The method of  claim 1 , wherein the act of defining an occlusal edge of the tray body comprises creating a cutting surface that intersects the receptacle and virtually removing a portion of the tray body that is located in the gingival direction from the cutting surface. 
     
     
         3 . The method of  claim 1 , further comprising rendering a virtual stop member that connects to the tray body and matches at least a portion of the virtual model, wherein the transfer tray further includes a physical stop member that corresponds to the virtual stop member and wherein the physical tray body has a first Shore hardness and the physical stop member has a second Shore hardness that is greater than the first Shore hardness. 
     
     
         4 . The method of  claim 3 , wherein the virtual stop member includes a posterior section that matches a portion of a molar tooth and an anterior section that matches a portion of an anterior tooth. 
     
     
         5 . The method of  claim 4 , wherein the virtual stop member further includes a flexible section that connects the posterior section and anterior section to each other. 
     
     
         6 . The method of  claim 5 , wherein the flexible section has a generally rectangular cross-section in a plane normal to its longitudinal axis and wherein the cross-section has an occlusal-gingival dimension greater than its facial-lingual dimension. 
     
     
         7 . (canceled) 
     
     
         8 . The method of  claim 3 , wherein the physical receptacle is adjacent to a region of material having a third Shore hardness that is less than the first Shore hardness. 
     
     
         9 . The method of  claim 1 , further comprising placing the orthodontic appliance in the physical receptacle. 
     
     
         10 . The method of  claim 1 , wherein the virtual model is obtained by directly scanning the dental structure of the patient. 
     
     
         11 . The method of  claim 1 , wherein the virtual model is obtained by scanning either a positive or negative replica of the patient's dental structure. 
     
     
         12 . The method of  claim 1 , wherein the virtual receptacle is open-ended in a generally gingival direction to facilitate occlusal detachment of the transfer tray from the orthodontic appliance. 
     
     
         13 . The method of  claim 1 , wherein the virtual tray body further includes a virtual frangible web that extends across at least a portion of the gingival side of the virtual receptacle. 
     
     
         14 . The method of  claim 1 , wherein the frangible web includes a line of weakness. 
     
     
         15 . The method of  claim 1 , wherein the gingival edge generally rises and falls based on the occlusal-gingival positions of three or more appliances along the dental arch. 
     
     
         16 . The method of  claim 1 , wherein the orthodontic appliance includes a custom base, and wherein the custom base has a configuration that matches the virtual model when the appliance is in the desired location. 
     
     
         17 . The method of  claim 1 , further comprising decreasing the size of the virtual receptacle in at least one dimension such that the virtual receptacle has a configuration that presents an interference fit in relation to the virtual appliance. 
     
     
         18 . A method of bonding an orthodontic appliance to a patient's dental structure comprising:
 obtaining a virtual model of a patient's dental structure;   determining a desired location for a virtual orthodontic appliance on the model;   providing a virtual receptacle at the desired location, wherein the virtual receptacle has a configuration that matches at least a portion of the appliance;   deriving a virtual tray body extending across at least a portion of the model and at least a portion of the receptacle remote from the model, wherein the act of deriving a virtual tray body includes the act of defining a gingival edge of the tray body that intersects the virtual receptacle;   forming the transfer tray by rapid prototyping, wherein the transfer tray includes a physical tray body and a physical receptacle sufficient to releasably retain the appliance that correspond to the virtual tray body and virtual receptacle respectively;   placing the appliance in the physical receptacle;   applying an adhesive to the surface of the orthodontic appliance;   placing the transfer tray over the patient's dental structure; and   hardening the adhesive.   
     
     
         19 . The method of  claim 18 , further comprising detaching the transfer tray from the appliance by urging the transfer tray in a generally occlusal direction. 
     
     
         20 . The method of  claim 18 , wherein the physical tray body includes a frangible web that extends across at least a portion of the gingival side of the virtual receptacle, and further wherein the act of detaching the transfer tray from the appliance includes fracturing the frangible web. 
     
     
         21 . A transfer tray for use in bonding of an orthodontic appliance comprising:
 an orthodontic appliance having a base for bonding to a tooth surface;   a receptacle for the orthodontic appliance having a configuration matching a portion of the appliance facing away from the base to releasably retain the appliance; and   a tray body extending across at least a portion of the model and at least a portion of the receptacle remote from the model, wherein the gingival edge of the tray body intersects the receptacle, and further wherein the tray body comprises a rapid prototyping material.   
     
     
         22 . A method of bonding an orthodontic appliance to a patient's dental structure comprising:
 providing an orthodontic transfer tray having a receptacle and an orthodontic appliance received in the receptacle;   placing the transfer tray over the patient's dental structure;   bonding the appliance to the patient's dental structure with an adhesive; and   detaching the transfer tray from the appliance by urging the transfer tray in a generally occlusal direction, wherein the act of detaching the transfer tray includes fracturing a portion of the tray that extends across at least a portion of a gingival side of the receptacle.   
     
     
         23 . The method of  claim 22 , wherein the transfer tray fractures along a line of weakness. 
     
     
         24 . The method of  claim 22 , wherein at least a portion of the appliance protrudes through the gingival edge of the transfer tray at the time the transfer tray is placed over the patient's dental structure.