Retention means for dental impression trays

Claim 1

In combination with a dental impression tray having a substantially rigid body having a bottom and upstanding outer walls defining a cavity in the shape at least of a portion of the mouth and jaw for receiving impression molding materials, retention means for holding said molding material in said cavity in the mouth and upon separation from said mouth, said retention means comprising a sheet consisting of a central carrier film a layer of selected adhesive applied on each surface of said film, and a peel-away foil cover disposed over each adhesive layer, one of said covers being removable to secure said sheet to the surface of said impression tray, and the other one of said covers being removable on application of the molding compound to said tray, the adhesive layer to be in contact with the surface of said tray being selected to have an enhanced holding strength with respect to the tray than the holding strength of the adhesive layer selected to be in contact with the molding compound relative to the compound, both of said adhesive layers having a holding strength preventing the separation of said adhesives from said central carrier.