Millions of people have them in their mouths, yet their widespread use in treating cavities is one of the more contentious issues in dentistry. So-called silver amalgam fillings contain about 50 percent mercury, with the remaining material made from a powder of silver, tin, zinc, and copper. Some experts are concerned that the release of microscopic amounts of mercury vapor—a consequence of chewing food, grinding teeth, and exposing the fillings to hot substances—might cause neurological problems or kidney damage, particularly in sensitive populations, such as children and pregnant women. Others, including the American Dental Association, say the safety data are reassuring. The Food and Drug Administration is taking a closer look.
The American Dental Association supports the agency's review but says that, based on the available evidence, limitations on the use of amalgam fillings or warning labels directed to certain types of patients are not warranted. "We've looked at silver amalgams harder than any other filling dental material, and there's just no evidence that it harms any of the sensitive groups," says J. Rodway Mackert, a spokesperson for the ADA and a professor of dental materials at the Medical College of Georgia's School of Dentistry.
Following the settlement of a lawsuit earlier this week, the US Food and Drug Administration (FDA) has updated its consumer advice on mercury amalgam to say that it poses health risks to pregnant women, children, and the unborn.
The updated consumer advice, which is in the FDA's Center for Devices and Radiological Health (CDRH) section of the website (web address given at the end of this article), now states that:
"Dental amalgams contain mercury, which may have neurotoxic effects on the nervous systems of developing children and fetus."
"Pregnant women and persons who may have a health condition that makes them more sensitive to mercury exposure, including individuals with existing high levels of mercury bioburden, should not avoid seeking dental care, but should discuss options with their health practitioner."
"FDA has moved to a more neutral course, while still recognizing the serious health risks posed by amalgam in particular for children and unborn children, for pregnant women, and for those with mercury immuno-sensitivity."
In addition to drawing conclusions as a joint committee when they met in September 2006, members of the FDA's advisory panel on mercury and amalgam issued personal statements that said, among other things, the agency should consider introducing a practice of informed consent for patients receiving amalgam, and that the labelling should be changed to restrict use of amalgam in pregnant women and children.