Mercury in Dental Amalgam

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What are Dental Amalgam Fillings?

Sometimes referred to as “silver filling,” dental amalgam is a silver-colored material used to fill (restore) teeth that have cavities. Dental amalgam is made of two nearly equal parts:

  • liquid mercury, and
  • a powder containing silver, tin, copper, zinc and other metals. 

Amalgam is one of the most commonly used tooth fillings, and is considered a safe, sound, and effective treatment for tooth decay.

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Are Dental Amalgam Fillings Safe?

When amalgam fillings are placed in or removed from teeth, they can release a small amount of mercury vapor. Amalgam can also release small amounts of mercury vapor during chewing. People can absorb these vapors by inhaling or ingesting them. However, the U.S. Food and Drug Administration (FDA) considers dental amalgam fillings safe for adults and children over the age of six.

FDA regulates dental amalgam as a medical device. FDA is responsible for ensuring that dental amalgam is reasonably safe and effective. Among other things, FDA also makes sure the product labeling for dentists has adequate directions for use and includes applicable warnings.

Background: Since the 1990s, FDA, the Centers for Disease Control and Prevention (CDC) and other government agencies have reviewed the scientific literature looking for links between dental amalgams and health problems. CDC reported in 2001 that there is little evidence:

  • that the health of the vast majority of people with dental amalgam is compromised, or
  • that removing amalgam fillings has a beneficial effect on health.

In 2002, FDA published a proposed rule to classify dental amalgam as a class II medical device with special controls. In 2008, FDA reopened the comment period for that proposed rule. After reviewing all comments, FDA issued a rule in 2009.

More information from the FDA:

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Are There Alternatives to Using Dental Amalgam Fillings?

Presently, there are five other types of restorative materials for tooth decay:

  • resin composite
  • glass ionomer
  • resin ionomer
  • porcelain
  • gold alloys

The choice of dental treatment rests with dental professionals and their patients, so talk with your dentist about available dental treatment options.

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How Does Amalgam Waste Affect The Environment?

If improperly managed by dental offices, dental amalgam waste can be released into the environment. Although most dental offices currently use some type of basic filtration system to reduce the amount of mercury solids passing into the sewer system, dental offices are the single largest source of mercury at sewage treatment plants. 

The installation of amalgam separators, which catch and hold the excess amalgam waste coming from office spittoons, can further reduce discharges to wastewater. Without these separators, the excess amalgam waste will be released to the sewers.

From sewers, amalgam waste goes to publicly-owned treatment works (POTWs)HelpPublicly-Owned Treatment WorksA water treatment facility, as defined by Section 212 of the Clean Water Act, that is used in the storage, treatment, recycling, and reclamation of municipal sewage or industrial wastes of a liquid nature, and is owned by a municipality or other governmental entity. It usually refers to sewage treatment plants. (sewage treatment plants). POTWs have around a 90% efficiency rate of removing amalgam from wastewaters.  Once removed, the amalgam waste becomes part of the POTW's sewage sludge, which is then disposed:

  • in landfills.  If the amalgam waste is sent to a landfill, the mercury may be released into the ground water or air.
  • through incineration.  If the mercury is incinerated, mercury may be emitted to the air from the incinerator stacks.
  • by applying the sludge to agricultural land as fertilizer.  if mercury-contaminated sludge is used as an agricultural fertilizer, some of the mercury used as fertilizer may also evaporate to the atmosphere.

Through precipitation, this airborne mercury eventually gets deposited onto water bodies, land and vegetation. Some dentists throw their excess amalgam into special medical waste containers, believing this to be an environmentally safe disposal practice. If waste amalgam is improperly disposed in medical waste bags, however, the amalgam waste may be incinerated and mercury may be emitted to the air from the incinerator stacks.  This airborne mercury is eventually deposited into water bodies and onto land. 

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