Dental amalgam has been proven safe and effective for years, yet unfounded controversy still surrounds it, a Medical College of Georgia researcher says.

Dentists have used amalgam, an alloy of mercury with at least one other metal, in fillings for over 200 years. Amalgam fillings don't contain enough mercury to cause potential health problems associated with larger doses, says Dr. Rod Mackert, professor of dental materials in the MCG School of Dentistry Department of Oral Rehabilitation.

"The dose makes the poison," he says, quoting 16th century Swiss physician Paracelsus. A person would need between 265 and 310 amalgam fillings before even slight symptoms of mercury toxicity could be felt. A person with seven fillings, which is average, absorbs only about one microgram of mercury daily. About six micrograms are absorbed daily from food, water and air, according to the Environmental Protection Agency.

To create a dental filling, liquid mercury dissolves and reacts with a powder of silver, tin and copper, forming a compound that contains no free mercury. "Anti-amalgam activists say mercury is soaked into metal powder, like water into a sponge, and can come back out of the fillings, but that's not at all true," Dr. Mackert says…