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http://www.usatoday.com/news/health/2006-04-18-dental-mercury_x.htm


Mercury fillings safe, studies find

By Elizabeth Weise, USA TODAY
Children who got "silver" dental fillings containing mercury Amalgam showed no neuropsychological or neurobehavioral differences compared with kids who got fillings of a polymer composite, say two new studies out Wednesday.

The studies in the Journal of the American Medical Association try to resolve a heated debate over Amalgam fillings, but groups that believe mercury in Amalgam is harmful disputed the findings and the ethics of testing them on children.

No large, randomized trials had previously been done to address the possible affects of mercury ingested from mercury amalgam dental fillings. A known potent neurotoxin, mercury is believed by some to pose a danger as minute amounts of it enter the body through the mouth.

Mercury amalgam has been used in dentistry for 150 years. Fillings made from it are 40% to 50% mercury. For over a century amalgam was believed to be inert, but about 25 years ago researchers discovered that amalgam fillings emit small amounts of mercury vapor. But until today, there were no large studies of harm from the mercury exposure.

In the first study, 534 New England children seen at five community health dental clinics between the ages of 6 to 10 were randomly assigned to receive either amalgam or tooth-colored composite fillings. Researchers at Children's Hospital Boston studied the children's neuropsychological and kidney function over the next five years and found no differences between the groups. The children were given IQ, memory and visual tests.

The second study compared two groups of children at a school system in Lisbon, Portugal. The 507 children, between 8 and 10 years old, were randomly assigned fillings with either amalgam or composite material.

The researchers found that children with mercury amalgam fillings were exposed to higher levels of mercury than those with composite fillings but that the low levels detected — about one microgram per liter of urine — had no measurable effects.

"We looked at a whole battery of behavioral and neurological tests, including memory, concentration and nerve-conduction velocities. We did this every year for seven years," says Timothy DeRouen, the first author on the paper and a professor at the school of dentistry at the University of Washington. "We saw no difference in the two groups in any of these measures."

The International Academy of Oral Medicine and Toxicology, a group that promotes mercury-free dentistry and believes that mercury amalgam fillings can cause autism, long-term neurological damage and Alzheimer's disease, disputed the findings.

"Until the doses of mercury that we've measured are shown to be safe — and that's not going to happen — then they should stop using the material," says David Kennedy, a dentist and past president of the anti-mercury group.

The group filed ethics complaints against the institutions involved, including Harvard University, the University of Maine and the University of Washington, for "outrageous" experiments on children.

DeRouen at the University of Washington countered that mercury amalgam fillings have been the standard of care in dentistry with 70 million being implanted every year in the USA. But the entire discussion may soon be moot. Silver fillings and fillings in general are going out of style.

Cavities in adult teeth are down 15% since the late 1980s, according to the Centers for Disease Control and Prevention.

That's because of better oral hygiene, fluoridation and tooth sealants that prevent decay, says Fred Eichmiller, a dentist at the American Dental Association Foundation in Gaithersburg, Md.

Today, amalgam makes up about 30% of fillings while composite is used in 70%, Eichmiller says. The reason seems to be more about aesthetics than mercury.

"Patients like the tooth-colored composite fillings," he says. Tweet