The present Opinion reviews only the toxicology of elemental and inorganic mercury being relevant to amalgam safety considerations.Local adverse effects in the oral cavity are occasionally seen with dental amalgam fillings,including allergic reactions and an association with clinical features characteristic of lichen planus, but the incidence is low (< 0.3% for all dental materials in general) and usually readily
managed. Regarding systemic effects, elemental mercury is a well-documented neurotoxicant,especially during early brain development. Inorganic mercury also constitutes a hazard to kidney function. In some scientific reports the presence of dental amalgam has been suggested to be associated with a variety of systemic adverse effects, particularly developmental neurotoxicity as well as neurological and psychological or psychiatric diseases. However, theevidence for such effects due to dental amalgam is weak.