The Benefits and Risks of Dental Amalgam

The controversy surrounding the safety of dental amalgam—a mixture of metals, including potentially-toxic mercury, used to fill in areas of a tooth where decay has been removed—is decades long. The American Dental Association (ADA) and other health organizations assert amalgam is safe for most patients, although there is a small group of people for whom alternative filling materials may be safer. If you have a cavity that needs to filled and your dentist plans to use amalgam, you may be interested in understanding the benefits and potential risks of this material.

What Is Dental Amalgam?

Dental amalgam is composed of silver, tin, copper, and mercury. It has been a primary material for dental use for over 150 years. It often is often referred to as a silver tooth filling because of the color.

Amalgam fillings are an effective way to replace the area of a tooth that has been destroyed by dental caries (cavities) and to prevent further decay. Amalgam is very hard when it dries, is durable and long-lasting, and is less expensive than other types of dental filling materials (such as polymer filling material). 

Risks of Amalgam Fillings

On the whole, amalgam is safe, but there are a few things to consider before you or your child receives an amalgam tooth filling.

Mercury Vapor

Mercury, the only metal that is liquid at room temperature, releases a type of vapor that can be inhaled into the lungs and then travel to various parts of the body, possibly causing adverse effects in organs such as the kidneys and the brain.

For this reason, the safety of using it in dental fillings has long been a matter of debate and concern. Although research findings regarding safe levels of the metal has had mixed results, at one time the consensus largely was that dental amalgam fillings may be toxic for everyone and should be replaced by a safer dental filling material.

Bioaccumulation

The steady accumulation of a chemical in the tissues or organs of the human body is called “bioaccumulation.” This process is thought to occur as a result of mercury in amalgam fillings. Although the type of mercury in fillings differs from that found in fish, this bioaccumulative process also occurs from mercury-poisoned seafood. The FDA reports that exposure to mercury vapor may accumulate in certain tissue in the body, such as the kidneys and the brain. But, there has not been sufficient evidence to prove that organ damage results from this build-up of mercury.

Allergies

Some people are allergic to components in amalgam fillings, such as mercury, copper, silver, or tin. An allergic reaction may result in oral lesions (sores in the mouth) or other reactions. Those who have reactions to amalgam fillings are encouraged to discuss alternative options (other than amalgam) for dental filling material.

Recent Studies

Although much of the clinical research data shows mixed results when it comes to the safety of mercury in dental amalgams, the American Dental Association continues to assert that the practice is a safe option for most patients.

In its 2009 position paper, reaffirmed in 2016, the ADA states "Studies continue to support the position that dental amalgam is a safe restorative option for both children and adults. When responding to safety concerns it is important to make the distinction between known and hypothetical risks.”

Nevertheless, the FDA recommendation against use in the certain high-risk patients is based on several recent studies. A 2019 review of the data, published by the International Journal of Environmental Research and Public Health, suggests that mercury exposure from dental amalgams may be associated with many maladies, including:

• Neurological (the brain and nervous system) disease
• Multiple sclerosis
• Alzheimer’s disease (for those who are 65 or older with dental amalgams)

According to the study authors, “New epidemiological studies are starting to emerge providing stronger evidence favoring a connection of dental amalgams with some neurological diseases. The data showed that Individuals exposed to amalgam fillings had a higher risk of Alzheimer’ s disease.”

A Word From Verywell

Although the FDA does not advise the public to replace amalgam fillings and explains that “Removing sound amalgam fillings results in unnecessary loss of healthy tooth structure, and exposes you to additional mercury vapor released during the removal process,” this information is not meant to be a substitute for your dentist’s advice. Before deciding on which type of filling material to select, it’s vital to discuss the issue with a dental professional. 

Those who believe they have an allergy to mercury (or other materials in amalgam fillings such as tin, silver or copper) may need to talk to a dental professional about alternative filling material.