Straight 'n' clear thermoforming plastic

Abstract

Thermoforming of plastic sheets over a model includes varying the thickness in the area that is stretched over the model so that when it thins it becomes more uniform in thickness. The plastic sheet is fabricated in a substantially uniform thickness but with a preformed a complex profile or 3D area that partially builds in part of the area that would be stretched so that it thins much less than a flat sheet. Combinations of these elements may also be made.

1 . A plastic sheet for thermoforming of dental devices comprising a sheet having at least two areas of different thickness to compensate for slump during thermoforming, and wherein at least one area is more resilient than at least one other area of the sheet.  
     
     
         2 . A plastic sheet for thermoforming of dental devices comprising a preformed dentition structure.  
     
     
         3 . A plastic sheet as in  claim 3 , having generally uniform thickness.  
     
     
         4 . A plastic sheet as in  claim 4  comprising polystyrene.  
     
     
         5 . A plastic sheet as in  claim 5  wherein the sheet more than 80% translucent after thermoforming.  
     
     
         6 . A plastic sheet for thermoforming over a model, comprising a sheet that is thicker where the plastic stretches over the model and is formed in a 3D prototype so that the weakened area during formation is stretched less than 25%.