Silver fillings, or amalgams as dentists refer to them, are made of alloy that usually contains combinations of silver, copper, tin and mercury. So when the media start talking about the dangers of mercury, amalgam is almost always mentioned as a possible source of mercury poisoning in humans, a claim which is absolutely false, according to dental professionals.

An article in the Feb.10 New York Times reported that the United Nations environmental conference held in Nairobi, Kenya called for a world-wide crackdown on mercury pollution. That same story went on to list various sources, including silver fillings, which expose humans to the highly toxic heavy metal.

But the claim that mercury in amalgam causes mercury poisoning, autism, Alzheimer’s disease, and multiple sclerosis or other neurological diseases is simply misleading, says dentist and clinical assistant professor of the Department of Restorative Dentistry and Biomaterials, Cynthia Trajtenberg, of the University of Texas Dental Branch at Houston.

“Amalgams have been around for more than 100 years, because amalgam is an excellent restorative material,” Trajtenberg says. “There is no scientific evidence of a connection between neurological or other diseases and the use of amalgam. The removal of amalgam does not cure or prevent any of those diseases or other diseases.”

Heavy Backing by Medical Societies

Her statement is backed by numerous medical organizations including the American Dental Association, Alzheimer’s Association, the American Academy of Pediatrics, the Autism Society of America, and the National Multiple Sclerosis Society. They all agree that there is no link between silver fillings and mercury toxicity causing neurological diseases.

A June 4, 1998, editorial in the New England Journal of Medicine says there is no evidence linking dental amalgams to health concerns, such as coronary heart disease and multiple sclerosis and that after extensive investigation researchers concluded “that dental amalgams do not pose a serious health risk.”

Last fall, the American Dental Association (ADA) released a statement that said “Dental amalgam (silver filling) is considered a safe, affordable and durable material that has been used to restore the teeth of more than 100 million Americans.”

Misinformed

Despite evidence showing that dental amalgams are safe, some patients insist on having all the amalgams removed, Trajtenberg says. She recently encountered just such a patient at the Dental Branch’s clinic. The patient’s physician told her to remove all metals from her mouth to eliminate exposure to mercury.

“The physician told the patient something that is not scientifically based and the patient believed it,” Trajtenberg says. “That physician was misinformed and created fear and anxiety in the patient.”

How Can it Be Safe?

Saying that the mercury in amalgam can cause harm is a little like saying the chloride in table salt can kill you. Shaking pure chloride on a juicy T-bone steak or over a tofu salad is a bad idea. The chemical will ruin the food, and force a scene as you spit out the offensive muck.

But combine the chloride with just the right amount of sodium and you create the tasty flavor enhancer called table salt.

The mercury in silver fillings is not harmful because the mercury is transformed in the process of making an alloy much like sodium and chloride are completely transformed when combined to make table salt.

“Amalgam is made by mixing mercury with other metals, such as silver, copper and tin,” Trajtenberg says. “The mercury binds to the other metals to make a stable alloy, and therefore is safe for dental applications.”

Tried, True, Solid and Safe

Amalgam is so popular because it is so stable and tough, surviving more than 30 years in the jaws of life. On the other hand, composite fillings last only about seven years. For the oral health of the general public, amalgam fillings certainly have been cost-effective.

In the 90s, there was an attempt to replace the mercury in amalgams with gallium, a rare metallic element. Gallium was tested in large part because of the public’s unfounded concerns about mercury in fillings, Trajtenberg says. But gallium showed more wear than fillings made with mercury. Dentists eventually abandoned gallium as an alternative to mercury.

Silver fillings do have one main downside. They are not aesthetically pleasing, so amalgams are not used on the front teeth simply because they aren’t attractive.

And German dental researchers have reported rare allergic reactions to mercury, but Trajtenberg says she never has seen an allergic reaction in her 10 years of clinical practice. She points out that an allergic reaction to an alloy is not the same as being poisoned by mercury. And mercury is not the only metal to cause allergies. In rare cases, some patients have even reported allergies to noble metals such as gold.

“The selection of the dental material should be something chosen between the patient and the dentist,” Trajtenberg says. But the dentist has the responsibility to tell the patient the benefits and drawbacks of each different material, including how long it lasts and how much it costs. “When I see patients, I tell them the benefits of having certain materials in the mouth but also the limitations,” she says.

Trajtenberg practices what she preaches. She recently replaced an amalgam that had been in her mouth since she was eight years old with a new mercury-based amalgam. “I personally chose amalgam over other dental options because it is a very good restorative material when it is properly placed,” she says.

Trajtenberg advises anyone concerned about amalgams to read the ADA literature on the subject and talk to your dentist.

UPDATED: 3-17-2003

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