When having a cavity filled, there are a few different materials to choose from. Over the years, there has been some controversy about the safety of some of those materials. Patients sometimes ask dentists the question “are dental fillings toxic?”

According to the majority of dentists, medical associations, and government agencies, the answer to this is a resounding “No.” But it’s understandable where some of the doubts and confusion come from when some have promoted the idea that dental fillings are dangerous. Learning the facts about dental fillings and the concerns surrounding them can help patients decide for themselves.

Dental Filling Materials

Dental fillings typically fall into four categories:

• Porcelain (ceramic)
• Composite resin (quartz or glass combined with resin, which is a hard polymer)
• Gold
• Amalgam (liquid mercury combined with powdered silver, tin, or copper)

The fears about toxicity center around only one of these materials: Amalgam. The fact that amalgam uses mercury, a substance that is known to be poisonous, is the basis for the belief that they are harmful.

Why, then, are amalgam fillings still around? And even though many dentists have switched to other filling materials, why do many of them seem unconcerned that patients still have old amalgam fillings?

Some people do wish to get rid of amalgam fillings once and for all. But numerous studies have failed to find any scientific evidence that amalgam fillings are linked to mercury poisoning or any other health issues. 

The Claims Against Amalgam Fillings

Most people think of amalgam fillings as “silver” fillings because of their color. Many adults have some in their mouths and don’t realize that they aren’t actually silver, but are made with mercury.

Dentists started using amalgam fillings way back in the 1800s. Mixing liquid mercury with metal alloys produced a durable and inexpensive substance that was easy to work with. Amalgam fillings last about twice as long as some of the other materials that are available today.

These fillings remained the most common type until the 1970s when questions arose about their safety. It was feared that amalgam fillings could cause mercury poisoning, which can harm the brain, heart, kidneys, lungs, and immune system. 

Claims were made that the mercury in amalgam fillings was causing serious diseases. Heart disease, multiple sclerosis, cancer, arthritis, Crohn’s disease, and many other conditions were blamed on fillings. There was even some anecdotal evidence that symptoms eased after fillings were removed from patients. 

Concerns about amalgam were addressed through several scientific studies. The research found no conclusive evidence of a connection between the fillings and the diseases. 

Much of the controversy was stoked by a Colorado dentist named Hal A. Huggins. He developed a business plan around the removal of amalgam fillings and teeth that had root canals using the material. It should be noted that Dr. Huggins’ dental license was ultimately revoked due to questions about the financial motives behind his claims.

What’s Really Going On With Amalgam Fillings?

Part of the confusion about whether dental fillings are toxic is due to the fact that there are different kinds of mercury. Methylmercury is an organic compound that can enter the bloodstream when ingested. This is the type of mercury found in fish. Overexposure, especially in fetuses and infants, can be dangerous.

The mercury used in fillings is elemental mercury. Unlike other types of mercury, it is non-toxic if ingested. Even swallowing pieces of an amalgam filling or the mercury from a broken thermometer (also elemental mercury) is not harmful. It isn’t absorbed into the body that way and won’t cause mercury poisoning.  

It can, however, emit low levels of mercury vapor that may enter the bloodstream through the lungs. Small amounts of vapor may be present when the filling materials are being mixed, and can also be released if a patient grinds his or her teeth. But these tiny amounts of vapor do not pose a risk. Typically the only way to be exposed to dangerous amounts of elemental mercury vapor is through unprotected occupational exposure—not from dental fillings. 

When considering health issues and amalgam fillings, problems usually occur due to an allergy to the materials rather than mercury poisoning. 

Widespread Agreement About the Safety of Fillings

Multiple organizations have agreed that amalgam fillings are safe and pose no health risk. The following professional institutions have made public statements supporting this:

• Amerian Dental Association
• The Mayo Clinic
• U.S. Food and Drug Administration (FDA)
• U.S. Environmental Protection Agency (EPA)
• National Capital Poison Center
• American Academy of Pediatrics
• New England Journal of Medicine
• National Council Against Health Fraud
• Consumer Reports
• Alzheimer’s Association
• Lupus Foundation of America
• Autism Society of America
• National Multiple Sclerosis Society
• American Cancer Society

Should You Replace Your Fillings?

The debate over amalgam fillings might lead to some people wondering if they should have them removed just to be safe. The general consensus of medical and dental professionals is to leave it in, as long as it is still in good shape. The exception to that would be if the patient is allergic, in which case it should be replaced right away.

One reason for this opinion is that the act of drilling to remove the filling can release more mercury vapor than exists from the filling staying in place. Also, the removal will require further drilling into the healthy part of the tooth to get rid of all of the amalgam filling material.

Most dentists have moved away from using amalgam due to improvements made in the durability of other materials, such as resin. They may also make that choice in an attempt to avoid patients’ concerns about safety—even if they are unfounded.

Most dentists agree that the amount of danger from existing amalgam fillings is so small that it is best to leave them alone until they wear out, crack, or otherwise need to be replaced. Different materials can be used in the new replacement filling, and for any brand new fillings that are needed in the future.

A Final Word on Fillings

Cavities are a widespread problem and dental fillings are a necessary solution. It is wise for patients to be well informed about any dental work they need, but they can rest assured that dental fillings are not toxic. 

Patients should discuss any questions or concerns about their dental health with their dentist. Our online search tool provides a database of dentists all over the country who can help explain the options.