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Mercury Fillings: They're Not Risky

Mercury Vapors Not Easily Absorbed by Body

Why Mercury Fillings Are Safe

Mercury amalgam fillings are "100% safe," says J. Rodway Mackert, DMD, PhD, professor of dental materials at the School of Dentistry of the Medical College of Georgia in Augusta. Mackert is a spokesman for the American Dental Association.

In fact, the World Health Organization, the Alzheimer's Association, and the National Multiple Sclerosis Society have all issued statements with a similar message, Mackert tells WebMD.

"Dental amalgam restorations are considered safe," says a WHO consensus statement. In rare instances, there is an allergic reaction to the filling, the statement notes. However, "the small amount of mercury released from amalgam restorations, especially during placement and removal, has not been shown to cause any other adverse health effects."

"According to the best available scientific evidence, there is no relationship between silver dental fillings and Alzheimer's," says the Alzheimer's Association web site.

"There is no scientific evidence to connect the development of multiple sclerosis (MS) with mercury-based dental fillings," says the National Multiple Sclerosis Society web site. "Poisoning with heavy metals, such as mercury, lead, or manganese, can damage the nervous system and produce symptoms, such as tremor or weakness, similar to those seen in MS. However, the underlying mechanism of nerve damage is different from MS, as is the pattern of illness caused by heavy metal poisoning."

The Science

In creating amalgam fillings, mercury is chemically combined with silver, Mackert explains. It's the chemical reaction between powdered silver and tin -- and liquid mercury -- that creates a material stable and safe enough for the human mouth.

"When liquid mercury is combined with silver, the chemical reaction reduces the amount of mercury that is released by nearly 1 million-fold," Mackert tells WebMD. "That's why it can be used in fillings."

Questions about mercury fillings began surfacing in 1979, when technology became available to measure the mercury vapor that the fillings emitted, he explains. "When we could measure the vapor, we found it wasn't zero, but it was a very small number. That was the concern. People began looking at how much vapor is released and the effects."

The Research

Since then, numerous well-conducted studies have shown that there is no need for concern, says Mackert. "In order to produce [toxic mercury] levels in fillings, you would have to have 450 to 500 fillings in your mouth. Humans don't have that many teeth. Most people have 32 teeth, and with their wisdom teeth out, it's 28. So it doesn't add up," he tells WebMD.

Among the studies:

  • In 2003, T.W. Clarkston, one of the world's leading mercury toxicity experts, published a study in The New England Journal of Medicine looking at mercury exposure from food, paints, vaccines, and dental fillings. The conclusion: "Patients who have questions about the potential relation between mercury [vapor from amalgam fillings] and degenerative diseases can be assured that the available evidence shows no connection."

  • An important twin study conducted in Sweden -- comparing nearly 600 adopted and "reared together" twin sets, all about age 66 - concluded: "This study does not indicate any negative effects from dental amalgam on physical or mental health or memory functions in the general population over 50 years of age." That 1996 study appeared in the journal Community Dental and Oral Epidemiology.

  • Another study published in 2003 looked at neurological and cognitive function among 550 healthy working adults. That study showed no association between mercury fillings and "any detectable deficits in cognitive or fine motor functioning." The study appeared in the journal Environmental Health Perspectives.

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