The Trouble With Mercury Fillings

Can amalgam fillings make you sick? Experts can’t agree.


Xray by Ceoln/Flickr (CC)


If you’ve ever had a dental filling, chances are you’ve got some mercury in your mouth. Those so-called silver fillings are a mixture of liquid elemental mercury and powdered silver, tin, copper, and other trace metals that hardens into a solid material that dentists have considered an excellent solution for cavities for more than a century.
But concern has been growing as to the safety of these fillings, with some experts citing dental mercury’s dangers, especially to the kidneys and the nervous system. In March, the International Academy of Oral Medicine and Toxicology filed suit against the U.S. Food and Drug Administration, charging the agency with failure to protect Americans from the risks of dental amalgam mercury. Despite reassurances from the FDA and the American Dental Association, more and more patients are demanding alternatives to mercury fillings. 

Why has mercury been used in particular? Because it’s the only metal that is liquid at room temperature and bonds well with the powdered mixture, according to the FDA. It’s strong and long-lasting and less expensive than other filling materials: Amalgam fillings last about 12 years and average $110 to $200 each, while alternative resin-based composite fillings last about five to seven years and range from $135 to $240 each, according to Oakland dentist Sharon Albright, D.D.S. And the mercury in dental amalgam is elemental mercury, which is absorbed via vapor into the lungs; it’s considered less dangerous than methyl mercury, which is found in dietary sources such as certain types of fish and is absorbed through the digestive system.

The truth is mercury fillings aren’t great, but perhaps they’re not as bad as one might think, Albright says.

“In general, you don’t want mercury in your mouth,” she says. “I don’t put them in. But mercury is the only filling material we’ve had for so long, and if it were really that deadly, we’d have heard a lot more about its effects by now.”

Resin composite fillings are made of ceramic and plastic and have been used on front teeth for years. Only in the past decade has composite technology improved enough so that it can be used on back teeth. 

Composite resin is placed on the tooth while in a soft putty form, then zapped with blue light to harden into a solid filling, Albright says. Once set, the dentist files the filling so that it won’t adversely affect the patient’s bite. Another benefit to composite resins is that they don’t require the dentist to drill out healthy tooth matter, like amalgam fillings do. And since composite resins don’t contain mercury, there’s no danger of the element being washed down drains or released as vapor.

Some patients swear that replacing mercury fillings with composites has improved their health. Oakland resident Louise Dunlap, 76, had her first mercury filling at the age of 21, and over the years collected seven more. The thought of spending thousands of dollars to remove them did not appeal to her at first.

“I had a great old-fashioned dentist when I lived on the East Coast, and it came up a few times as I started to read about toxins in mercury fillings,” she says. “He thought it sounded crazy, especially since the composite material doesn’t last as long as dental amalgam. So I didn’t think much more about it.”

But in 2011, Dunlap had a heart attack. She recovered, but her nutritionist encouraged her to consider removing the mercury fillings as part of a holistic health effort. Dunlap found a dentist deeply committed to mercury-free fillings, and over the course of a year had eight crowns replaced—at a cost of almost $11,000. A few months after replacing her mercury fillings, she noticed something unusual.

“My old dentist had told me again and again that I was destined for periodontal disease, because I had these severe gum pockets,” she says. “He told me I would need deep cleanings for the rest of my life. But after the mercury was removed, the pockets were gone.”

So what’s the bottom line? Like many other health decisions, whether to replace dental amalgam with an alternative is up to the patient, Albright says, adding that removing mercury fillings could be more dangerous to one’s health than leaving them in if they’re still sound.

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