PURPOSE: The titled reinforcing liquid, prepared by dissolving either one of polycarbonate resin and polysulfone resin or both with glass fibers in methylene chloride solvent, polymerizable by the application to the tooth and crown of a polymethyl methacrylate resin, and having high durability.

CONSTITUTION: In a reinforcing liquid for a dental prosthetic material of a denture base and crown consisting of a molded polymethyl methacrylate resin, either one of polycarbonate resin and polysulfone resin or both and glass fibers are dissolved in methylene chloride. The resultant reinforcing liquid for the dental prosthetic material is then applied to the prosthetic material in a thin layer, which is polymerized under pressing, heating, etc. The methylene chloride is then evaporated to form a film from the polycarbonate resin, etc. The water absorption of the prosthetic material is eliminated by coating the prosthetic material with the reinforcing liquid for the dental prosthetic material, and the outflow of the residual monomer is prevented to improve the abrasion resistance remarkably and inhibit the invasion of various germs without giving out offensive smells and any deterioration in hue.