The Debate Over Mercury in Dental Fillings

The debate over whether mercury in dental fillings can leach out and cause a wide range of health problems -- from multiple sclerosis and cancer to Alzheimer's disease --refuses to die down.

The mercury in dental fillings is an amalgam, or blend, of copper, silver, and mercury that has been used for more than 150 years. Silver dental fillings contain very small amounts of inorganic mercury, which is not easily absorbed by the human body, according to the American Dental Association (ADA) and other public health groups.

The ADA's position that dental amalgam is a safe and effective material to fill cavities is supported by the U.S. Public Health Service, the European Commission and the World Health Organization, and many studies. In late 2004, a group called the Life Sciences Research Office Inc. reviewed seven years worth of scientific studies and concluded that there is insufficient evidence "of a link between dental mercury and health problems, except in rare instances of allergic reactions."

However, Austria, Canada, Denmark, Germany, and Sweden have banned or discouraged mercury fillings, especially in children and pregnant women.

How Easily Is Mercury Absorbed?

"The mercury in fish is methyl mercury and is much more easily absorbed by the gastrointestinal tract, whereas elemental mercury from an amalgam is almost not absorbed," says ADA spokesman J. Rodway Mackert, DDS, a professor in the School of Dentistry at the Medical College of Georgia in Augusta. And if it's not absorbed, it can't cause any problems, he says.

But "people feel passionately and won't take no for an answer," Mackert says. "Its perplexing. I thought that a number of times after studies came out showing silver fillings were safe, people would begin to realize that the mercury used in amalgam fillings doesn't cause problems and they would drop it."

According to Mackert and the ADA, there is certainly no reason to avoid amalgam fillings. "I have them and my wife and kids do too," he says. "In fact, a survey done asked dentists what type of filling they prefer in their own mouth and amalgams were preferred in their back teeth because they last longer."

Silver Fillings vs. Porcelain Fillings

Silver fillings are not exactly attractive, which is why most dentists prefer white or porcelain fillings in the more visible part of their smile, he notes.

"We are always improving the white filling," he says. "They don't last quite as long, but are still very durable and a lot of people like them because they look like a real tooth," he says.

They haven't really caught on because "silver is so easy to use," says Nicholas Davis, DDS, president of the American Academy of Cosmetic Dentistry. "We can put it in the mouth when the mouth is wet and it doesn't take an advanced technique, so it's easy to fall back on," he says, adding that it's harder to use the newer white fillings, which are technique sensitive.

Still, "mercury is a poison, but so is fluoride, and fluoride in the right concentration will keep teeth from decaying," he says, likening the mercury controversy to the equally heated debate over the fluoridation of the public water system. The problem with the latter, some say, is that excess fluoride can lead to dental fluorosis, in which the teeth become stained yellow or brown or flecked with white spots and can be toxic to other parts of the body.