A SILVER-TIN ALTERNATIVE TO DENTAL AMALGAMS

This paper describes a novel technology for a mercury-free metallic di rect filling material, a substitute to dental amalgams. The consolidat ion relies both on cold-welding that takes place under moderate pressu re between suitably surface-treated silver particles and on silver-tin intermetallic compound formation at ambient temperature. A dilute aci d is used for removing the silver surface oxide layers, thereby promot ing the cold-welding process. The condensability, namely the ability o f a loose powder to undergo consolidation within a short time duration , at body temperature and under moderate pressure has been investigate d for a variety of mixtures of silver, tin, and prealloyed silver-coat ed intermetallic powders. The resulting metallic composite material di splays transverse rupture strength values higher than those of amalgam s and somewhat lower values of compressive strength and Knoop hardness .