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The next time you need a filling, your dentist may give you a choice: amalgam or composite? Although amalgam fillings have been controversial in the past decade because they contain mercury, most experts believe the mercury won't threaten your health. Here's what you need to know before making this choice.

The most obvious difference is appearance. Amalgam fillings are silver-colored, while composite fillings are tooth-colored. Patients can also get fillings made of other metals, such as gold, but these are not considered amalgam fillings.

Amalgam fillings are made of a combination that's about half mercury, plus silver, tin, and copper. Composite fillings are made with a combination of glass and resin.

If this were the only difference, patients and dentists would choose composite fillings every time. After all, who wants a mouth full of metal? But there are other considerations. First of all, amalgam fillings are stronger and more durable than composite fillings. If you need a filling in a spot that gets a lot of pressure -- such as a back tooth -- an amalgam filling may be the best choice, says Cynthia Sherwood, DDS, a family dentist in Independence, Kansas, and spokeswoman for the Academy of General Dentistry.

Also, amalgam fillings can cover larger surfaces than composite fillings. In some cases, the only alternative to an amalgam filling is a crown. Finally, amalgam fillings are usually significantly less expensive than composite fillings, Sherwood says. The costs per filling range from about $75 to $145 for amalgam and $150 to $200 for composite.

Despite these limitations, composite fillings are a popular choice for patients and dentists. "Composite fillings are terrific for a lot of situations," Sherwood says. She often uses them for smaller repairs on highly visible teeth. But if a dentist ever says that composite fillings are the only option, the patient should consider getting a second opinion, she says.

Even in small amounts, mercury can be a deadly poison. However, in a filling, mercury binds with other metals to form a highly durable, stable compound, and only an infinitesimal amount escapes from fillings -- less, experts believe, than the amount of mercury we already get in our environment every day.

As reported by the American Dental Association (ADA), a filling might release 1 to 3 micrograms per day, compared to the 5 to 6 micrograms of mercury we get daily from food, air, and water. (A microgram equals 35.2 billionths of an ounce.)

Amalgam fillings have been used for more than 100 years, and they continue to have the trust of dentists around the world. The American Dental Association, the Academy of General Dentistry, the American Academy of Pediatrics, The World Health Organization, The Food and Drug Administration, The Alzheimer's Association, and the National Multiple Sclerosis Society all agree that these fillings are safe.

Not everyone is convinced, however. In November 2002, G. Mark Richardson, a former Canadian public health official, testified that mercury exposure from amalgam exceeds the standards set by the US Environmental Protection Agency. In testimony before the US House Government Reform Committee, Richardson recommended reduction or elimination of the fillings. He said there is ample evidence that mercury from a pregnant woman's fillings can cross the placenta and reach the fetus and also contaminate breast milk. "It is apparent that dental amalgam leads to excessive exposure in a large proportion of the population," Richardson said.

The majority of dentists, however, believe there's nothing to worry about. "I am convinced that amalgam fillings are safe," says Sherwood. "I use them on my own family."

-- Chris Woolston, M.S., is a health and medical writer with a master's degree in biology. He is a contributing editor at Consumer Health Interactive, and was the staff writer at Hippocrates, a magazine for physicians. He has also covered science issues for Time Inc. Health, WebMD, and the Chronicle of Higher Education.

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Last updated January 20, 2009
Copyright © 2003 Consumer Health Interactive

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