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concentrations are not necessarily indicative of mercury load in body tissues (Lorscheider et al., 1995) or severity of clinical symptoms (Draschet al.,2002).

It has been postulated that amalgam fillings could be part of the explanation for the explosion of learning problems and autism in children since World War II, a time period corresponding with the introduction and widespread use of mercury amalgam.

The American Dental Association (ADA) acknowledges that amalgam contains mercury and reacts with other substances. However, to date the ADA maintains that amalgam continues to be a safe material. U.S. Department of Health and Human Services released the following statement in 1991, “At the mercury doses produced by amalgam fillings, the evidence is not persuasive that the wide variety of non-specific symptoms attributed to fillings and "improvement" after their removal are attributable to mercury derived from the fillings. Conversely, the evidence is not persuasive that the potential for toxicity at the levels attributable to dental amalgams should be totally disregarded. The potential for effects at levels of exposure produced by dental amalgam restorations has not been adequately studied.”

Despite ADA and U.S. Department of Health standing, other countries have made progress. Austria and Sweden already have a total ban, and in Germany mercury fillings carry a health warning against their use in children and pregnant women. The health authorities of various countries, including Canada, Germany, France, the United Kingdom and Austria have recommended against the placement of an amalgam in certain individuals such as pregnant and nursing women and persons with impaired kidney function.

How does mercury toxicity present itself?

All toxic presentations, whether acute, chronic, or subacute, are difficult diagnoses because multiple organ systems are affected (eg, central nervous system, kidney, mucous membranes) and can mimic a variety of other diseases.

Exposure to mercury from amalgam occurs through several avenues: inhalation of air containing elemental mercury released from the amalgam; ingestion of amalgam particles abraded from restored surfaces and of saliva into which both elemental and corrosion produced inorganic mercury products have dissolved; and ingestion of amalgam particles generated during dental restorative procedures (placement, restoration, or removal). Chronic and intense acute exposure causes skin and neurological symptoms. The classic triad found in chronic toxicity is tremors, gingivitis, and erethism (ie, a constellation of neuropsychiatric findings that includes insomnia, shyness, memory loss, emotional instability, depression, anorexia, vasomotor disturbance, uncontrolled perspiration, and blushing).

Without a complete history, mercury toxicity, especially in elderly individuals, can be misdiagnosed as Parkinson disease, senile dementia, metabolic encephalopathy, depression, or Alzheimer disease.