Dental products and procedures

Abstract

Polymeric shells which fit over one or more natural teeth to change the perceived color of the teeth, and optionally to provide orthodontic support. The shells can be prepared by thermoforming selected polymeric sheets which contain optical additives over a physical image of the teeth, or by depositing polymeric compositions containing optical additives over a physical image of the teeth, or by additive manufacturing based upon a digital image of the teeth. The optical additives cause the combination of the shell and the teeth to have a desired appearance. At least part of the shell preferably has transparency greater than 75%, particularly greater than 85%.

1 . A self-supporting shell which (a) can be fitted over one or more teeth to change the perceived color of the one or more teeth, and (b) comprises two or more levels, at least one of the levels being a first level comprising a polymeric composition comprising a polymer and a first concentration of one or more optical additives, and at least one other second level comprising a polymeric composition comprising a polymer, the second layer (i) comprising one or more optical additives in a second concentration which is different from the first concentration or (ii) being free from optical additives. 
     
     
         2 . A self-supporting shell according to  claim 1  which comprises two or more layers, at least one of the layers being a first layer comprising a polymeric composition comprising a polymer and a first concentration of one or more optical additives, and at least one other second layer comprising a polymeric composition comprising a polymer, the second layer (i) comprising one or more optical additives in a second concentration which is different from the first concentration or (ii) being free from optical additives. 
     
     
         3 . A self-supporting shell according to  claim 2  which comprises (1) a first layer which is not on the outside of the shell when the shell is fitted over the one or more teeth and which contains a first concentration of the one or more optically active additives, and (2) a second layer which (i) is on the outside of the shell when the shell is fitted over the one or more teeth and (ii) contains a second concentration of the one or more optically active additives, the second concentration being less than the first concentration. 
     
     
         4 . A self-supporting shell according to  claim 1  wherein the shell comprises a laminate comprising a layer which (i) contains an optical brightener and (ii) is not part of the exterior surface of the shell. 
     
     
         5 . A self-supporting shell according to  claim 1  which is for use in an orthodontic procedure and which has a flexural modulus of more than 1500 MPa. 
     
     
         6 . A self-supporting shell according to  claim 5  which has a thickness of 0.5 to 0.8 mm. 
     
     
         7 . A self-supporting shell according to  claim 1  which is for use in changing the appearance of the tooth or teeth and which has a flexural modulus of less than 800 MPa. 
     
     
         8 . A self-supporting shell according to  claim 7  which has a thickness of 0.2 to 0.6 mm. 
     
     
         9 . A self-supporting shell according to  claim 1  which has an innermost level having a total visible light transmission greater than about 75%. 
     
     
         10 . A self-supporting shell according to  claim 9  which has been applied over the tooth or teeth, and the innermost level of the shell extends over a gum line beyond the upper edge of the teeth and/or the lower edge of the teeth. 
     
     
         11 . A method of making a self-supporting shell according to  claim 1  which comprises depositing a succession of polymeric compositions onto a physical image of the tooth or teeth. 
     
     
         12 . A method of making a self-supporting shell according to  claim 1  by three-dimensional printing based on a digital image of the teeth. 
     
     
         13 . A sheet which can be thermoformed over a model of one or more teeth to provide a self-supporting shell which can be fitted over one or more teeth to change the perceived color of the one or more teeth, the sheet comprising two or more levels, at least one of the levels being a first level comprising a polymeric composition comprising a polymer and a first concentration of one or more optical additives and at least one second level comprising a polymeric composition which (a) has a second concentration of one or more optical additives, the second concentration being different from the first concentration, or (b) is free from optical additives. 
     
     
         14 . A sheet according to  claim 13 , wherein there is no additive at one or more levels in the sheet. 
     
     
         15 . A sheet according to  claim 13  wherein the polymeric composition is based on a polymer selected from the group consisting of elastomers, polyesters, polyurethanes, polyolefins, acrylic resins, methacrylic resins, polyamides, polycarbonates, polyethers, ionomer resins, cellulose esters, cellulose ethers and fluoropolymers. 
     
     
         16 . A sheet according to  claim 13  wherein the one or more optical additives comprises light-scattering particles selected from the group consisting of one or more of titanium dioxide, barium sulfate, calcium carbonate, boron nitride, silica, mica and zinc oxide, and the concentration of at least one of the optical additives is different at different levels going through the thickness of the sheet. 
     
     
         17 . A sheet according to  claim 13  wherein the sheet is a laminate having two or more layers of different polymeric compositions, and the laminate contains an optical brightener in a layer which, when the sheet is thermoformed, is not an exterior surface of the shell. 
     
     
         18 . A sheet according to  claim 13  wherein the sheet is a laminate having two or more layers of different polymeric compositions and the laminate comprises (i) a first layer which has a first concentration of an optical additive, and (ii) a second layer which provides an exterior surface of the laminate and is free from the optical additive or which contains a second concentration of the optical additive, the second concentration being substantially less than the first concentration. 
     
     
         19 . A polymeric sheet according to  claim 13  which has a uniform thickness of 0.10-2 mm and which comprises a polymer and one or more optical additives, wherein the concentration of the one or more optical additives is different at different levels going through the thickness of the sheet, and the one or more optical additives comprise one or more light-scattering particles selected from the group consisting of titanium dioxide, barium sulfate, calcium carbonate, boron nitride, silica, mica and zinc oxide. 
     
     
         20 . A polymeric sheet according to  claim 13  which has a uniform thickness of 0.10-2 mm and which has an exterior level having a transparency of greater than 85%.