FDA has finished publishing this version on 28 July 2009

Dental Amalgams

Questions and Answers on Dental Amalgam

1. What is dental amalgam?

Dental amalgam is the 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. Mercury concentration in dental amalgams is generally about 50% by weight, while the silver concentration ranges from 20-35%.

2. What is FDA's role in dental amalgam?

Dental amalgams are medical devices and are regulated by FDA's Center for Devices and Radiological Health (CDRH). CDRH is responsible for ensuring that medical devices are reasonably safe and effective and that the labeling has adequate directions for use and any appropriate warnings.

3. What are the safety concerns about dental amalgam?

Dental amalgams contain mercury, which may have neurotoxic effects on the nervous systems of developing children and fetuses. When amalgam fillings are placed in teeth or removed from teeth, they release mercury vapor. Mercury vapor is also released during chewing. FDA's rulemaking (described in question 7) will examine evidence concerning whether release of mercury vapor can cause health problems, including neurological disorders, in children and fetuses.

Since the 1990s, FDA and other government agencies (CDC, NIH) have reviewed the scientific literature looking for links between dental amalgams and health problems. In September 2006, an advisory panel to the FDA reviewed FDA's research and heard presentations from the public about the benefits and risks of mercury and amalgam.

You can read the summary of the panel meeting at: Joint Meeting of the Dental Products Panel (CDRH) and the Peripheral and Central Nervous System Drugs Advisory Committee (CDER) - September 6-7, 2006

In addition, a complete transcript is available at: http://www.fda.gov/ohrms/dockets/ac/cdrh06.html#dentalproductspanel

4. Are there other dental filling materials that can be used instead of amalgam?

Yes, there are several other types of dental fillings.

Resin composites are tooth-colored materials made from powdered glass and resin compounds. When composites were initially introduced, they were not very strong and were used primarily in the front teeth. Newer composites are stronger, although they still tend to wear more than metal-based materials and generally need earlier replacement.

Glass ionomer cement is also a tooth-colored material. It is not usually used for long-term fillings because it breaks easily.

Porcelain, gold, and other metals are also used as filling materials. Gold and porcelain are used for inlays, veneers, crowns, and bridges. These fillings are made outside the mouth and cemented into place after they are formed.

5. Should I have my amalgam fillings removed and replaced with these other materials? If I have a cavity, should I choose to get amalgam fillings?

FDA does not recommend that you have your amalgam fillings removed. FDA is engaged in a rulemaking that may lead to revised labeling. It is also reviewing evidence about safe use, particularly in sensitive subpopulations.

If you are concerned about the possible health effects of amalgam fillings, you should talk with your qualified health care practitioner.

Dental amalgam fillings are very strong and durable, they last longer than most other types of fillings, and they are relatively inexpensive. You may want to weigh these advantages against the possibility that dental amalgam could pose a health risk, until further information is conveyed through the rulemaking (see question 7) or otherwise.

6. Should pregnant women and young children use or avoid amalgam fillings?

The recent advisory panel believed that there was not enough information to answer this question.

Some other countries follow a "precautionary principle" and avoid the use of dental amalgam in pregnant women. Advice about dental amalgams from regulatory agencies in other countries is available below.

Canada: http://www.hc-sc.gc.ca/ahc-asc/media/nr-cp/1996/1996_63_e.html
France: http://afssaps.sante.fr/ang/pdf/amalgam.pdf
Sweden: http://www.kemi.se/templates/Page.aspx?id=5233

Pregnant women and persons who may have a health condition that makes them more sensitive to mercury exposure, including individuals with existing high levels of mercury bioburden, should not avoid seeking dental care, but should discuss options with their health practitioner.

7. What is the next step for FDA?

In 2002, FDA published a proposed rule to classify dental amalgam as a class II device with special controls. On April 28, 2008, FDA reopened the comment period for that proposed rule. The comment period will be open until July 28, 2008. After reviewing all comments, FDA intends to issue a final rule classifying dental amalgam.

By July 28, 2008, FDA is requesting comments supported by empirical data and scientific evidence concerning this classification and special controls for dental amalgam. In addition, if class II (special controls) is the appropriate classification for these devices, FDA requests comment on whether the two types of special controls proposed by FDA in 2002 (materials and labeling) provide reasonable assurance of the safety and effectiveness of these devices and on whether the special controls FDA described in 2002 should be revised in light of the recommendations and with respect to the discussions by the 2006 joint committee.

Controls on the Materials. For example, should the material controls proposed by FDA address conformance to recognized consensus standards that make recommendations for testing, compressive strength, and identifying the mercury vapor released by the device?

Labeling Controls. For example, how should labeling controls, if any, address the disclosure of composition, including mercury content, and precautions regarding use of the device in sensitive subpopulations composed of individuals who respond biologically at lower levels of exposure to mercury than the general population? If so, which subpopulations should be included (e.g., children under age 6, pregnant and lactating women, hypersensitive or immunocompromised individuals)? Should the labeling controls require more specific patient labeling (e.g., informing patients of identified sensitive subpopulations of the mercury content, the alternatives to the device and their relative costs, and health risks associated with the failure to obtain dental care)?

For the agency's future analysis of benefits and costs of the regulatory options for dental amalgams, FDA also requests comments, including available data, on the following questions:

(1) How many annual procedures use mercury amalgams? What are the trends?
(2) What are the differences in cost between amalgams and alternative materials (e.g., composite, other metals, ceramics, etc.)? Are there differences in replacement lives?
(3) What are reimbursement rates for dental amalgam and the alternative materials?
(4) How would labeling describing the risks of amalgam for certain subpopulations (e.g., children under age 6, pregnant and lactating women, hypersensitive or immunocompromised individuals) affect the demand for, and use of, mercury amalgam? How would the risks included in the labeling be communicated to those subpopulations?
(5) What is the current exposure to mercury for patients? For professionals? What would be the reduction in exposure associated with the use of alternative materials?