July 28, 2009 -- The mercury used in dental amalgam fillings is not at a level high enough to cause harm in patients, according to the FDA, which today issued its final regulation on the controversial tooth filling material.
However, the agency tightened its controls on mercury fillings, classifying the encapsulated amalgams now commonly sold to dentists as Class II devices, deemed a moderate risk, instead of the lower risk Class I devices.
Dental amalgams, the silver-colored material used to fill teeth after removal of a cavity, include liquid mercury and a powder that contains silver, tin, copper, zinc, and other metals. When the fillings are placed in the teeth or removed, or during chewing, mercury vapor is released, according to the FDA. At high levels, mercury can cause adverse health effects to the brain and kidneys.
A representative from an organization that opposes mercury fillings called the new ruling "an outrage," while the American Dental Association issued a statement agreeing with the decision.
FDA's Final Rule on Amalgams
At a media advisory to announce the final rule, the FDA's Susan Runner, DDS, said, ''The best available scientific evidence supports the conclusion that patients with dental amalgam fillings are not at risk for mercury-associated adverse health effects.
''Long-term clinical studies in adults and children age 6 and older with dental amalgam fillings have not established a causal link between dental amalgam fillings and adverse health effects,'' says Runner, the agency's acting director of the Division of Anesthesiology, General Hospital, Infection Control, and Dental Devices in the Center for Devices and Radiological Health.
The scientific evidence on the effects of mercury fillings on developing fetuses and children younger than age 6 is limited, she says, but "the scientific evidence that is available suggests these populations also are not at risk."
Over the past 20 years, according to Runner, the FDA has received 141 adverse event reports regarding dental amalgams, with none resulting in death.
Tuesday's action comes about a year after the agency agreed to issue a final rule after being sued by consumer groups and individuals concerned about the health effects of mercury exposure.
Included in the final regulation is the decision to classify dental amalgam as a Class II or moderate risk device, giving the FDA authority to impose special controls with the goal of ensuring safety and effectiveness.
The special controls are spelled out in a guidance document that includes recommendations on labeling and other parameters. Among the labeling recommendations:
• A warning against the use of the filling material in those with a known mercury allergy
• A warning to dentists and other dental professionals to use adequate ventilation when handling the dental amalgam
• A statement talking about the risk and benefit of the dental amalgams, including the risks of inhaled mercury vapor. The statement is meant to help patients and dentists make informed decisions.
Previously, the FDA had classified the two separate parts of the amalgam, including elemental mercury and the metal powder alloy. Now the product is purchased in a different form than in previous years, Runner says. ''Many years ago, dentists would purchase the alloy and the mercury separately and mix it in the office."
These days, she says, they purchase it in an encapsulated form. "That was the form not classified before," she says.
FDA Ruling: Reactions
In a statement issued Tuesday, the American Dental Association said: "The American Dental Association (ADA) agrees with the U.S. Food and Drug Administration's (FDA) decision not to place any restriction on the use of dental amalgam, a commonly used cavity-filling material."
Leaving the decision up to patients and their dentists is the correct approach, according to the ADA. "The FDA has left the decision about dental treatment right where it needs to be -- between the dentist and the patient," ADA President John Findley, DDS, says in the statement.
Not everyone agrees, however. ''The final rule is an outrage," says Charles Brown, national counsel for Consumers for Dental Choice, a group against the use of mercury amalgams. ''It puts mercury 1 inch from a child's brain. It puts mercury directly to the fetus.''
Ideally, he says, the agency should have warned against the filling use for children, pregnant women, and nursing mothers.
Brown contends the FDA did an about-face, just a year ago saying that mercury from amalgam dental fillings may be toxic to children and developing fetuses.
As a practical matter, the new ruling will make little difference to many dentists, says Michael Sesemann, DDS, a dentist in Omaha, Neb., because he and many of his colleagues have discontinued using the amalgam mercury fillings in favor of other restorative materials.
"Amalgam filling use is in decline," he says, and he hasn't used it since 1997.
Other options, such as white composite or porcelain filling materials, look better and are preferred by many patients, he says.