Ever since research showed that mercury in standard amalgam fillings can escape, enter body tissues and impair organ function in test animals (NEWSWEEK, Oct. 15), people have been flooding the offices of anti-amalgam dentists. Blaming everything from persistent headaches to multiple sclerosis on mercury in their fillings they are demanding to have their mouths tested for mercury levels. Some are insisting that their amalgam fillings be yanked out. But just as parents overreacted to the 1989 Alar scare by hysterically grabbing apples out of their children’s lunch boxes, many risk-wary Americans misunderstand this threat. As a result, they can be exploited by unscrupulous dentists happy to replace amalgam fillings, at up to $500 a pop, in a procedure that may be more dangerous than leaving the fillings in.
One problem is that the machine used to measure mercury concentrations in the mouth was never intended for that purpose. It is designed to measure mercury in rooms, such as in thermometer factories. Few dentists know how to properly use the $5,000 analyzer, manufactured by Arizona Instrument Corp. Even when dentists recalibrate the device to test a mouth-size rather than a room-size sample of air, the results reveal little except that mercury is escaping from fillings, says University of Calgary dentist Murray Vimy, whose research on mercury in test animals touched off the latest fears. Those readings correlate well with how much mercury reaches body tissues, Vimy says, but there is no consensus on what constitutes a dangerous level. So dentists are inventing rules as they go. Dr. Joyal Taylor of San Diego, for instance, uses a simple guide: if the concentration exceeds what the government allows in a room, “that is reason for alarm.” Except that the probe measures mercury levels right after a patient chews, when they’re highest.
The Food and Drug Administration approved dental mercury in 1976 under a grandfather clause that excused the metal from tests for chronic toxicity. Although the American Dental Association insists the levels pose no hazard, a few dentists are pressuring the FDA to ban mercury until it’s proven safe. But even these activists do not recommend that healthy people have amalgam fillings removed. Although amalgam is soft when it goes into a cavity, it becomes so brittle that jettisoning old fillings can scatter specks of the toxic metal onto skin, into the lungs or down to the stomach. Taylor will therefore remove amalgam fillings only after placing a rubber dam in the patient’s mouth so she does not swallow mercury chips, swathing her from head to toe to prevent skin exposure and fitting her with a breathing piece so she inhales only oxygen. Without proper precautions, “you’ll be subjected to far more mercury in taking a filling out than in leaving it in,” says Dr. Robert Baratz of Boston’s Tufts University School of Dental Medicine.
The risk to any one of the 100 million or more Americans with amalgam fillings is relatively small. Still, risk-averse people may opt to fill new cavities with more expensive (and often less durable) porcelain, gold or composite resins. And since chewing releases mercury, it may be prudent to swear off a chronic bubble-gum habit. But since even a tiny risk multiplied by millions of Americans raises a significant public-health issue, the FDA is convening an advisory panel on mercury in March. Until then, anyone with mysterious health problems should consult a physician, not a dentist.
