Dental amalgam restorations: daily mercury dose and biocompatibility

Over the past 150 years, silver-tin-copper amalgam has been the most frequently used dental restorative material. Amalgam may be the single most frequently used implant material. In the early 1980s, researchers discovered that amalgam restorations release mercury vapor during chewing. This review describes the research that has led to an estimate of the daily dose of mercury that will be absorbed by a subject with a large number of amalgam restorations. Along the way, the history and chemistry of dental amalgam are outlined. The routes of absorption of liquid mercury, ionic mercury, organic mercury, and mercury vapor are also briefly described. The daily dose is found to be 14% of the threshold above which observable adverse neurological symptoms are expected. The review concludes with a summary of the research on the adverse effects of dental amalgam. As expected from the low daily dose, few adverse neurological symptoms have been reported. There is also little evidence of an association of amalgam restorations with neurodegenerative diseases, altered renal function, adverse pregnancy outcomes, or autoimmune diseases. There is a lack of data on neurobiological and neurodevelopmental effects on children who may be exposed to mercury from maternal amalgam restorations during gestation. Additional data on the role of amalgam, if any, in Alzheimers disease and multiple sclerosis are needed.