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.

1 . (canceled) 
     
     
         2 . 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 the one or more discontinuities of the first layer comprise a first window formed through said first layer.   
     
     
         3 . An appliance as in  claim 2 , 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. 
     
     
         4 . An appliance as in  claim 2 , wherein the first elastic modulus differs from the second elastic modulus by 25% to 600%. 
     
     
         5 . An appliance as in  claim 2 , wherein the first window is formed through the first layer vary along one or more of a mesial-distal axis, facial-lingual axis, and gingival-crown axis. 
     
     
         6 . An appliance as in  claim 2 , wherein the first window is formed through the first layer on a buccal wall of a cavity. 
     
     
         7 . An appliance as in  claim 2 , wherein the first window is formed through the first layer on a lingual wall of a cavity. 
     
     
         8 . An appliance as in  claim 2 , wherein the first window is formed through the first layer on an occlusal surface of a cavity. 
     
     
         9 . An appliance as in  claim 2 , wherein at least a region of the shell comprises a material reinforced with a structure comprising one or more of strips, wires, mesh, lattices, and networks. 
     
     
         10 . An appliance as in  claim 9 , wherein the structure comprises a polymer. 
     
     
         11 . An appliance as in  claim 9 , wherein the structure comprises a metal or alloy. 
     
     
         12 . An appliance as in  claim 2 , wherein at least a region of the polymeric shell comprises a metal or alloy. 
     
     
         13 . 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.   
     
     
         14 . The method of  claim 13 , wherein an appliance with a uniform elastic modulus is produced. 
     
     
         15 . The method of  claim 13 , wherein an appliance with one or more portions of differing elastic moduli are produced. 
     
     
         16 . The method of  claim 13 , wherein removing one or more portions of the first material layer forms one or more discontinuities. 
     
     
         17 . The method of  claim 16 , wherein the one or more discontinuities through the first layer comprise windows. 
     
     
         18 . A orthodontic system comprising:
 a plurality of dental appliances configured to move at least one tooth between a first position and a second position, each 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 the one or more discontinuities of the first layer comprise a first window formed through said first layer.   
     
     
         19 . An appliance as in  claim 18 , wherein the first window is formed through the first layer vary along one or more of a mesial-distal axis, facial-lingual axis, and gingival-crown axis. 
     
     
         20 . An appliance as in  claim 18 , wherein the first window is formed through the first layer on a buccal wall of a cavity. 
     
     
         21 . An appliance as in  claim 18 , wherein the first window is formed through the first layer on a lingual wall of a cavity.