Metal fillings with mercury are considered safe by the FDA.
For more than 150 years, metal dental fillings have been a common way to repair diseased teeth, according to the U.S Food and Drug Administration. The most common metal filling is a dental amalgam. It's made of several different metals and is the least expensive option available to patients with a cavity. The American Dental Association (ADA) notes that more than 100 million Americans have amalgams.
Dental Amalgam
A dental amalgam is made of several metals, according to the FDA. Around 50 percent of an amalgam's weight is from elemental mercury, a liquid mercury that releases vapor. The remaining materials are in a powdered alloy consisting of silver, tin and copper.
Once a dentist has drilled into a tooth to remove the decay, she mixes the powdered alloy with the liquid mercury and inserts it into the tooth cavity she has created. The mixture then hardens and is considered stronger and more durable than alternate fillings. Mercury is an important component of the amalgam because it is the only metal that is liquid at room temperature and bonds well with the other metals in the powdered alloy.
Other Metal Fillings
Although less common, gold alloys are a desirable material for fillings, according to the ADA. They contain gold, copper and other trace metals. Gold is a good choice because it is strong and resists corrosion. It also allows the dentist to remove the least amount of healthy tooth before restoring the area.
Base metal alloys are another option. They are non-noble metals that provide a strong, tarnish-resistant filling. Some patients, however, might be sensitive to these metals, says the ADA.
FDA Concerns
Because an amalgam contains mercury, many individuals are concerned it might be dangerous. FDA analysis of clinical studies has determined there is no significant health hazard from metal fillings. The agency does not recommend them for children under 6 years old, however. The mercury in the fillings is released as vapor and is processed by the lungs. This is different from the form of mercury found in fish --- methylmercury --- that is mainly absorbed through the digestive tract and is considered dangerous in high levels.
Composite Dental Fillings
Some dentists offer to replace dental amalgams with newer composite fillings, which are a combination of glass or quartz in a resin medium. Although they are more expensive and less durable than amalgams, they are tooth-colored and more cosmetically attractive. Replacing a dental amalgam is not recommended unless the current filling is failing or the tooth is showing decay, according to the MayoClinic.com. Removing the filling without a good cause could permanently damage the tooth. Other tooth-colored options include glass ionomers, a mixture of acrylic acids and fine glass powders, and porcelain blends, according to the ADA.
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