Studies show no evidence that they can cause brain damage or other neurological problems.

Advocacy groups and some dentists have long worried that the mercury contained in metal cavity fillings could be harmful to children. But two new studies, financed by the federal government and published in the Journal of the American Medical Association, refute that claim.

There are currently two kinds of fillings that can be used to fill cavities. The silver fillings (also called amalgam fillings) that have been used for more than a century are made of a combination of mercury and other metals. Only recently has their use begun to decline with the popularity of resin composite fillings. These composite fillings have been deemed more appealing, both because they don't contain mercury and because their white color makes them less noticeable.

The two studies, one performed in the U.S. and one in Portugal, compared the neurological status of children who had gotten amalgam fillings with those who were given composite fillings. Neither study showed any variance in memory, intelligence, or other mental functions between the two groups of children five years after they received their fillings. The study in the United States also compared kidney function between the two groups and, once again, found no difference. However, neither study looked at autism, which some parents worry may be caused by exposure to high levels of mercury.

"We didn't see any indications of harm to these kids," said Dr. Timothy DeRouen, a professor of biostatistics and dental public health sciences at the University of Washington, who led the study in Portugal and monitored more than 500 children between the ages 8 and 10 for any neurological effects. "And we tested them repeatedly over seven years."

"The newly published studies lend further support to the use of dental amalgam as a safe and effective restorative treatment option," reports the American Dental Association.

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