Controversy continues over exposure to mercury through dental fillings

September 13, 2004|by KATE COLEMAN

Kathy Myer of Shepherdstown, W.Va., recalled that she had a "tinny taste" in her mouth for a long time.

Although she doesn't have direct proof that the metallic taste she hated was caused by mercury in amalgam fillings in her teeth, the taste was gone after she had the fillings removed a couple of years ago, she said.

Myer, 48, also has TMJ - temporomandibular joint disorder - a syndrome caused by a problem of the joint that connects the lower jaw to the bones at the side of the skull. Myer wears a mouthpiece to alleviate her TMJ discomfort. Again, though she can't attribute it directly to the removal of her mercury fillings, she's noticed that she seems to have fewer TMJ symptoms than before she had the fillings removed.

She said her severe allergies have abated, but she's made a lot of nutrition- and health-related changes in her life, so she really can't pinpoint cause and effect.


The safety of mercury in amalgam dental restorations - fillings - is the subject of debate. Concerns have been raised about possible toxicity because vapor emitted from the fillings can be absorbed by the patient, according to information in a fact sheet on the Web site of the Centers for Disease Control and Prevention at

The American Dental Association's position is that the dental amalgam is safe, durable and affordable. Others, including Consumers for Dental Choice, are working to abolish mercury in dental fillings, claiming that mercury is related to various health problems.

Mercury is a shiny, silver-white, liquid metal. It can evaporate to form colorless, odorless vapors.

Mercury can combine with other elements to form inorganic compounds, and it can combine with organic material to form organic compounds such as methylmercury, which is the cause of concern for exposure in the environment, according to information on the Web site of the U.S. Environmental Protection Agency. Methylmercury is taken up and retained in higher organisms through the food chain, reaching high levels in fish and birds and mammals who eat fish.

Thus U.S. Food and Drug Administration officials caution women who are or might become pregnant, nursing mothers and young children about eating certain fish or large amounts of fish.

Exposure to high levels of elemental mercury vapor can result in damage to the nervous system, which can include tremors and mood and personality disorders, the EPA states. Also, exposure to "relatively high levels of inorganic mercury salts can cause kidney damage," and "adult exposure to relatively high levels of methylmercury through fish consumption can result in numbness or tingling in the extremities, sensory losses and loss of coordination."

The EPA says that metallic mercury released from dental fillings is people's most likely source of exposure, but the amount is "generally not considered to be high enough to cause adverse health effects." The FDA, U.S. Public Health Service and the World Health Organization have not found scientific evidence to support limiting the use of mercury-based fillings, according to information on the Web site of the National Toxicology Program Center for the Evaluation of Risks to Human Reproduction at on the Web.

Mercury has been used in dental amalgams for more than 150 years, and although tooth decay has declined thanks to fluoride, sealants and improved oral hygiene, dental amalgam fillings still are in use. There are alternative materials, but the most commonly used and less expensive of these cannot be used for large lesions, because they are not strong or durable enough, according to the CDC Web site.

Dr. J. Rodway Mackert Jr. is a dentist, professor of dentistry at the Medical College of Georgia and has a doctoral degree in materials science, formerly known as metallurgy, he said.

When the topic first surfaced 20 years ago, people didn't know about the possible effects of mercury from amalgam fillings, he said. Numerous studies have been done - with negative results. The amount of mercury emitted is very low. There is no link between mercury in fillings and neurodegenerative diseases, Mackert said.

The amount of methylmercury absorbed from eating risky fish once a week is seven times as great, he added. Mackert acknowledged that people sometimes are concerned about mercury in fillings, but added that he could talk somebody out of having alternative "white" fillings - made of different compounds.

"Both are completely safe," he said.

He added that anything - Vitamin A, for example - can be toxic in great enough amounts.

Myer is happy to have mercury containing fillings out of her mouth.

"I can't believe it's good to have mercury in your body," she said.

Many agree with her.

Among those who do are holistic practitioners, "biological" dentists and Consumers for Dental Choice, a nonprofit organization based in Washington, D.C. Among its goals is abolishing the use of mercury in dental restorations. Opponents of mercury in fillings have linked it to neurological diseases including multiple sclerosis and Alzheimer's disease.

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