Systems and methods for varying elastic modulus appliances

Abstract

The present invention provides improved devices, systems and methods for repositioning teeth from an initial tooth arrangement to a final tooth arrangement. Repositioning is accomplished with a system comprising a series of polymeric shell appliances configured to receive the teeth and incrementally reposition individual teeth in a series of successive steps. The individual appliances may be formed from layers having different stiffnesses (elastic moduluses), and the stiffnesses of successive appliances may be different, or both.

What is claimed is: 
     
         1 . A dental appliance comprising:
 a polymeric shell having cavities shaped to engage individual teeth, the polymeric shell comprising:
 a first layer being a discontinuous inner layer; 
 a discontinuity in the first layer; and 
 a second layer being a continuous outer layer and being formed over the first layer; 
   wherein one or more discontinuities of the first layer comprise a first window formed through said first layer.   
     
     
         2 . The dental appliance of  claim 1 , wherein the first layer has a first elastic modulus and the second layer has a second elastic modulus, the first and second elastic moduli being in the range from 0.5 to 5 GPa. 
     
     
         3 . The dental appliance of  claim 2 , wherein the first elastic modulus differs from the second elastic modulus by 25% to 600%. 
     
     
         4 . The dental appliance of  claim 1 , wherein portions of the dental appliance vary along one or more of a mesial-distal axis, facial-lingual axis, and gingival-crown axis. 
     
     
         5 . The dental appliance of  claim 1 , wherein the first window is formed through the first layer on a buccal wall of a cavity. 
     
     
         6 . The dental appliance of  claim 1 , wherein the first window is formed through the first layer on a lingual wall of a cavity. 
     
     
         7 . The dental appliance of  claim 1 , wherein the first window is formed through the first layer on an occlusal surface of a cavity. 
     
     
         8 . The dental appliance of  claim 1 , wherein at least a region of the polymeric shell comprises a material reinforced with a structure comprising one or more of strips, wires, mesh, lattices, and networks. 
     
     
         9 . The dental appliance of  claim 8 , wherein the structure comprises a polymer. 
     
     
         10 . The dental appliance of  claim 8 , wherein the structure comprises a metal or alloy. 
     
     
         11 . The dental appliance of  claim 1 , wherein at least a region of the polymeric shell comprises a metal or alloy. 
     
     
         12 . A method for producing a dental appliance, the method comprising:
 providing a mold of the patient's dentition;   forming a first material layer over the mold;   forming a window though the first layer; and   forming a second material layer over the first material layer so as to produce the dental appliance.   
     
     
         13 . The method of  claim 12 , wherein an appliance with a uniform elastic modulus is produced. 
     
     
         14 . The method of  claim 12 , wherein an appliance with one or more portions of differing elastic moduli are produced. 
     
     
         15 . The method of  claim 12 , wherein removing one or more portions of the first material layer forms one or more discontinuities. 
     
     
         16 . The method of  claim 15 , wherein the one or more discontinuities through the first layer comprise windows. 
     
     
         17 . An orthodontic system comprising:
 a plurality of dental appliances configured to move at least one tooth between a first position and a second position, each of the plurality of dental appliances comprising:   a polymeric shell having cavities shaped to engage individual teeth, the polymeric shell comprising:
 a first layer being a discontinuous inner layer; 
 a discontinuity in the first layer; and 
 a second layer being a continuous outer layer and being formed over the first layer; 
   wherein one or more discontinuities of the first layer comprise a first window formed through said first layer.   
     
     
         18 . The orthodontic system of  claim 17 , wherein portions of the dental appliance vary along one or more of a mesial-distal axis, facial-lingual axis, and gingival-crown axis. 
     
     
         19 . The orthodontic system of  claim 17 , wherein the first window is formed through the first layer on a buccal wall of a cavity. 
     
     
         20 . The orthodontic system of  claim 17 , wherein the first window is formed through the first layer on a lingual wall of a cavity.