Some health controversies never go away, and mercury in “silver” amalgam used for filling cavities is one of them. Dental amalgam is a mixture of copper, silver, tin and zinc; mercury is added for strength and durability. Some people claim that this amalgam is toxic and causes everything from cognitive problems to multiple sclerosis, and that existing fillings should be removed and replaced by other compounds. In recent years there have been petitions to the Food and Drug Administration (FDA) and local ordinances (including a proposed measure here in the city of Berkeley this year) to ban amalgam fillings or make it difficult for dentists to use them. Here are the facts:
- Mercury occurs naturally in the environment and also comes from industrial pollution. Just about all people have traces of it in their bodies, even if they have no amalgam fillings. At high levels, mercury can cause gastrointestinal, kidney and neurological damage; lower levels can harm fetuses, infants and young children. About 70 percent of the mercury in humans, on average, comes from fish, according to a study published in Environmental Science & Technology in March.
- There’s no convincing evidence of harm from the minuscule amounts of mercury that may be released from amalgam when you chew or when a filled tooth is damaged or drilled. In fact, numerous studies have found no increased risk. Notably a large, well-designed Harvard clinical trial in 2008 found no cognitive problems in children with amalgam fillings compared to those with other types of fillings.
- Scores of experts and government organizations have concluded that these fillings are safe—the FDA, Centers for Disease Control and Prevention, Environmental Protection Agency, National Institutes of Health, World Health Organization, U.S. Public Health Service, Health Canada, American Dental Association and virtually every other major dental organization.
- Once again I have to say “pay no attention to that man behind the curtain” regarding a segment on The Dr. Oz Show. It featured a demonstration purporting to show that brushing teeth containing amalgam releases “toxic” levels of mercury vapor in the mouth. This did not mimic real world conditions and was totally misleading. Here is a full critique of this show.
- Removing undamaged amalgam fillings is unnecessary, expensive and potentially damaging to teeth. Beware of dentists or other health care providers who propose testing you for mercury, unless you know you’ve had high exposure (for instance, if you work with heavy metals at your job) and/or you have the classic symptoms of mercury poisoning. And run for the hills if anyone tries to sell you “detoxification” supplements and programs that are supposed to counter the effects of mercury in dental amalgam—or for any purpose.
- Amalgam use is declining, partly because other substances are now also being used for fillings. Most of these are white composite materials, which are less visible than silver amalgam.
- One piece of semi-sweet news: Americans have been getting fewer cavities in recent decades, thanks to fluoride in toothpaste and drinking water and good dental hygiene. Unfortunately, millions of Americans can’t afford dental care, have few dentists in their area and/or live in areas where water isn’t fluoridated. If not for that, fillings in teeth—and the controversy about them—would probably soon pass into history.