[Dental amalgam: a toxicological evaluation]

During the latest decades the use of dental amalgam has been discussed with respect to potential toxic effects of the mercury component. In order to evaluate potential risks from this practice the recent literature is reviewed. Corrosion of fillings results in liberation of mercury. The absorption from this source in the Danish population can be estimated to be one to five micrograms/24 hrs. This exposure level is far below that accepted in occupational exposure and far below the minimum toxic level. Investigation of placental transfer of mercury has not provided any reason to avoid using amalgam during pregnancy. Micromercurialism or metal syndrome is claimed to be related to amalgam fillings. This syndrome consists mainly of complaints from the central nervous system, but also from muscles, joints and the gastrointestinal tract. The symptoms are non-specific and the documentation of the existence of such a syndrome related to mercury exposure is weak. The symptoms reported can be due to other chemical exposures, but psycho-social conditions may also play an important role. Information on disappearance of symptoms after removal of fillings may be a result of a placebo effect, which may be suggested until controlled experiments are performed. For this reason the use of chelating therapy is not indicated. Allergic contact eczema observed in few individuals is the only problem documented in connection with the use of amalgam fillings.