18th July 2007

The controversy over silver amalgam dental fillings started with their use and is, after a century, now drawing to a slow conclusion with the gradual recognition of amalgam poisoning and slow withdrawal of amalgam fillings from dentistry. In 2003, U.S. Representative Diane Watson (D-CA) has drafted a ''Mercury in Dental Filling Disclosure and Prohibition Act," which is intended to stop dentists from using amalgam to fill cavities. However, this bill was never passed.

Amalgam and mercury

Elemental mercury is the main ingredient in dental amalgams. Controversy over the health effects from the use of mercury amalgams began shortly after its introduction into the western world, nearly 200 years ago. In 1843, The American Society of Dental Surgeons, concerned about mercurial poisoning, required its members to sign a pledge that they would not use amalgam. In 1859, The American Dental Association was formed by dentists who believed amalgam was, "safe and effective." The ADA, "continues to believe that amalgam is a valuable, viable and safe choice for dental patients," as written in their statement on dental amalgam.

For many years the dental community maintained that mercury was tightly bound with other metal components and did not escape from amalgam fillings. However, studies have proven that mercury vapors do escape during chewing, brushing and when contacted with hot or acidic food. In 1993, the United States Public Health Service reported that, "amalgam fillings release small amounts of mercury vapor," but in such a small amount that it, "has not been shown to cause any … adverse health effects."

One study reported on levels of mercury vapor measured in the mouth after chewing. The mercury vapor level was fifty-four times higher in the mouth of an individual with amalgams than in the mouth of an individual without amalgams. The absorption rate of inhaled mercury vapor is extremely high: approximately 80% of the inhaled dose reaches the brain tissue within one blood circulation cycle.

It is known from animal research that mercury vapor is emitted continually from dental amalgam and is absorbed and accumulated in organs tissues (Danscher et al. 1990; Hahn et al., 1989, 1990; Lorscheider et al., 1995; Lorscheider and Vimy, 1991; Vimy et al. 1990). Humans with amalgam fillings have significantly elevated mercury levels in blood (Becker et al., 2002; Gottwald et al., 2001; Kingmann et al., 1998; Pizzichini et al., 2003; Zimmer et al., 2002), about 3 ± 5 times more mercury in urine (Becker et al., 2003; Gottwald et al., 2001; Kingmann et al., 1998; Zimmer et al., 2002) and 2 to 12 times more mercury in their body tissues (Draschet al. 1992, 1994; Egglestone and Nylander, 1987; Lorscheider et al., 1995; Nylander, 1986; Nylander et al., 1987) than individuals with out dental amalgam. It is interesting to note, however, that blood and urine