Mercury by itself is toxic, but using the heavy metal in dental work does not seem to pose a health risk. That's the finding of two separate studies, both published in the April 19 issue of the Journal of the American Medical Association. In them, investigators measured the neurological and kidney function of children who had cavities filled with silver amalgam (which contains mercury) vs. kids with fillings made from mercury-free material.

The new studies are the first randomized trials to look at the health impact of mercury vapor released from fillings. It's long been known that people with long-term exposure to mercury vapors can suffer tremors, memory loss, lack of coordination, and psychiatric ills. But there has been some dispute over whether the small amount of mercury in fillings could cause problems.

Both JAMA studies tracked several hundred children over a few years to find out. (The first followed 534 New England children, aged six to 10, with an average of 15 tooth surfaces restored over five years. The second looked at 507 children, aged eight to 10, in Lisbon, Portugal.) Both found that kids in the amalgam group had higher levels of mercury in their urine, but neither found any negative health affects as a result. Most importantly, there was no statistically significant difference in memory, IQ, attention, or visual motor function between the kids with amalgam fillings and those without.

What It Means:  The studies conclude that there's no reason to avoid amalgam fillings. In fact, silver fillings have some advantages over plastic ones. The amalgam typically lasts longer than resin composite materials—and it's usually a lot cheaper too.

From the Archive:
08/19/2002 White Is the New Mercury
12/11/1995 Are Your Teeth Toxic?