For more than 150 years, most Americans with tooth cavities have received the same treatment: a so-called “silver” filling that dentists have used to seal the tooth and prevent further decay. But what most patients don’t know is that those fillings can contain high levels of mercury and may be causing more problems than they solve.

Fillings are made of a material called amalgam, which today is composed of mercury (40%) and a powdered combination of silver, tin, copper, and zinc (60%). As its long use testifies, amalgam is a highly effective material where cavities are concerned. It’s relatively inexpensive, extremely durable, and bacteriostatic, which means it inhibits the bacteria that cause tooth decay to prevent further problems.

The earliest known use of amalgam to repair a cavity occurred in China, where a silver paste was used to repair a tooth in the year 659. The first form of the modern version was created by French dentist Auguste Taveau in 1816. In 1833, the amalgam was brought to New York City and advertised as new “silver fillings,” a name selected because of its jewelry connotations. Citing its poor performance, American dentists had the material banned soon thereafter. Refinements to amalgam at the turn of the century resulted in a more successful product and widespread acceptance.

Today, according to the American Dental Association (ADA), dentists fill more than 100 million cavities with amalgam every year. Yet studies show that almost half of all Americans are unaware that these fillings contain so much mercury, which may help the tooth but can harm the patient.

Mercury is a heavy metal whose notoriety is legend. Exposure to mercury can cause severe damage to the central nervous system resulting in everything from excitability and loss of memory to tremors and delirium. Most people are surprised to learn that once placed on a tooth, the mercury in dental amalgam off-gases over time and is released in vapor form as the filling ages—even after decades in our mouths, which means anyone with amalgam fillings is eating and inhaling this toxin in tiny quantities every day. Studies have also shown that mercury can escape into saliva and into the bloodstream via tooth pulp and roots.

photo: wonderferret

Even at low concentrations, research shows that mercury vapor can cause tremors, impaired cognitive skills and sleep disturbance, and indeed there is a wealth of anecdotal evidence that exposure to the mercury in fillings leads to migraines, rashes, mouth sores, nerve impairment, bodily shaking, and other maladies. According to a 2005 article in the Chicago Tribune, clinicians at one Chicago lab specializing in trace metals analysis have found that the amount of mercury in a person’s stool sample correlates with the number of amalgam fillings in their mouth. Other studies have found that absorption rates vary widely, with susceptible individuals absorbing up to 100 micrograms per day.

What’s lacking, however, is solid empirical evidence that the mercury we absorb from amalgam causes harm. With no studies able to provide such definitive proof, the ADA continues to maintain that mercury amalgam is safe. But at the same time, regulations require dentists to treat removed fillings as hazardous waste and use special disposal methods, a situation many health advocates see as a serious disconnect.

So what should we do if we have amalgam fillings or cavities that need repair? Here are our precautionary suggestions:

• First, talk to your dentist about your present fillings and future needs. If he or she doesn’t take your concerns about amalgam seriously, find a dentist who’ll listen and offer you some options.

• Existing amalgam fillings can be removed, but experts advise caution. When fillings are drilled out, a very fine amalgam dust is created that makes it easy for large amounts of mercury to be absorbed by the body during the procedure. To minimize this risk, ask your dentist to use a dental dam, irrigation to keep dust down, and constant a high-speed suction at the site to remove all the dust and filling remnants immediately.

• Seek and use healthier amalgam alternatives when fillings are needed. Many different types of mercury-free options are available. These include glass or quartz resin composites, glass ionomers, porcelain, and non-mercury alloys made from gold and other metals.

To learn more about the issue of mercury in dental fillings, visit Consumers for Dental Choice and read this recent article from the Hudson Valley’s Chronogram. For more information about amalgam alternatives, visit the American Dental Association (note that the ADA continues to vouch for the safety of mercury-based amalgam.)