ARE YOUR TEETH TOXIC?

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At the heart of the controversy, and at the center of Huggins' practice, is the tricky question of how much mercury is too much. No one denies that mercury is toxic in small doses. Nor is there any doubt that some mercury leaches out of fillings. In fact most people, with or without fillings, show trace amounts in their urine samples, measured in 1 or 2 parts per billion. Yet no adverse effects from mercury have been shown at levels below 25 ppb.

Despite the broad safety margin, there are reputable dentists who worry about amalgam. When their patients need new dental work, they offer fillings made of gold or plastic and ceramic composites. Gold, of course, is much more expensive than silver, and ceramic fillings don't hold up as well for molars, which must grind against one another. Yet most dentists stop short of encouraging their patients to have sound fillings removed. Healthy teeth have to be drilled out to accommodate new fillings, which rarely hold as well as the originals. And in removing the old fillings, dentists risk exposing patients to more mercury than if their teeth had been left alone.

Even in Sweden, where mainstream dentistry has been much more open to the possibility that mercury fillings might be poisonous, public health officials have been slow to endorse wholesale extractions. As a precaution, many Swedish women won't have their teeth filled during pregnancy. But in 1994, after an exhaustive review of the available literature, the Swedish National Board of Health and Welfare concluded that "there are at present no medical indications for recommending amalgam removal in order to relieve symptoms of general ill health."

Who is right about silver fillings? The American Dental Association, the World Health Organization and the Multiple Sclerosis Society have all declared them to be safe. Dentists have been filling teeth with amalgam since the early 1800s, and more than half of all Americans have them in their mouth without apparent ill effect. But as J. Rodway Mackert, an expert on dental materials at the Medical College of Georgia, points out, "it's impossible to prove something is entirely safe." And as long as there are people who believe their fillings are making them sick, there will be dentists happy to pull them out.

--Reported by Richard Woodbury/Colorado Springs