Research into non-mercury containing metallic alternatives

Many attempts have been made over the years with varying degrees of success to developing metallic alternatives to dental amalgam. Much of the difficu lty join achieving success is the inability to meet the physical, mechanica l and clinical criteria for an "ideal" alternative. An additional requireme nt for any new material is that it be "environmentally friendly"-both from a manufacturing standpoint and in use. Gold foil has been one of dentistry' s most successful direct filling materials, but is only used by few/select clinicians and is largely considered a lost art. Metal-modified glass ionom ers have achieved some success as crown buildup materials and direct restor atives in the primary teeth of children, but these are slowly being displac ed by improved composites. Several attempts have been made to develop metal -filled composites, but only one product is available for use as a crown bu ildup material. There is a long history of attempts to formulate an accepta ble gallium alloy. Early nickel-gallium formulations resulted in severe tum orgenicity in animal trials. Palladium-gallium-tin alloys were less toxic b ut still exhibited high latent expansion and severe soft tissue inflammatio n around implants and tissue-embedded particles. More recent attempts to fo rmulate silver-copper-gallium-indium-tin alloys resulted in better biocompa tibility, but clinical trials showed corrosion and latent expansion too sev ere for general clinical acceptability. Studies of consolidated silver mate rials have resulted in the development of a direct restorative system with favorable properties and biocompatibility, but no human trials have yet eva luated the material's clinical performance. The demands in today's market f or esthetics and regulatory pressures to reduce heavy metals in wastewater have resulted in less interest in metallic alternatives for amalgam. Future development will likely focus on improving polymeric composites in an atte mpt to meet the call for an amalgam alternative.