Mouthpiece with soft low-friction overlay

Abstract

A mouthpiece made of a relatively rigid thermoplastic substrate having a shape generally complementary to the wearer's dental arch; a layer of compliant, slippery material overlaid on the outer surface of the mouthpiece.

1 . A mouthpiece apparatus comprising: a substrate having a U-shaped cross section with a convex outer surface, the substrate formed to fit over one of an upper set and a lower set of a user's teeth; and an overlay portion of a slippery foamed polymer; the foamed polymer tenaciously applied as a compliant layer to an outer convex surface of the substrate. 
   
   
       2 . The apparatus of  claim 1  wherein the mouthpiece portion is made of a relatively rigid thermoplastic material having a shape generally complementary to a user's dental arch. 
   
   
       3 . The apparatus of  claim 2  wherein the substrate has a chemically reactive outer surface. 
   
   
       4 . The apparatus of  claim 3  wherein the reactive outer surface is coated with a first coating comprising a hydrophilic prepolymer intermediate, which is capable of forming a polyurethane-polyurea hydrogel-forming polymer, and which contains terminal isocyanate groups, such that at least a portion of said terminal isocyanate groups are covalently bonded to the surface of said substrate, forming covalent polyurea bonds and thereby resulting in the formation of a tie coat of a polyurethane-polyurea hydrogel-forming polymer, that adheres to the surface of the substrate, and wherein at least a portion of the terminal isocyanate groups of said polyurethane-urea prepolymer intermediate are present in the polyurethane-polyurea hydrogel-forming polymer, such that they remain free to react with other species. 
   
   
       5 . The apparatus of  claim 4  wherein the first coating is overcoated with a foamed second coating comprising a moisture-containing hydrogel-forming compound, further containing isocyanate-reactive chemical functional groups, such that a barrier coat of a hydrogel is formed upon the application of the second coating to the tie coat of the first coating.