The US Food and Drug Administration (FDA) issued a final regulation today, Wednesday, saying that at the levels dentists use for tooth cavity filling, elemental mercury in dental amalgam does not harm patients, although adverse health effects are known to occur at higher exposures.

Dental amalgam is made by combining mercury with other metals such as silver, copper and tin.

Under the new regulation, dental amalgam is classified as Class II, denoting moderate risk. Devices in Class II can be made subject to special FDA safety and effectiveness controls (in addition to the manufacturing standards required of all medical devices regardless of their risk level).

The announcement has received a mixed response. While the American Dental Association said they agreed with the FDA decision, a consumer group that is against using mercury in dental fillings said it showed contempt for children and the unborn.

The ADA said in a statement released earlier today that the new classification puts amalgam in the same category as gold and tooth-colored composite fillings, and puts the decision about dental treatment where it belonged, between the dentist and the patient.

ADA President Dr John Findley said dentists were doctors who specialized in oral health, and that the FDA decision underscored what the Association has long supported:

“A discussion between dentists and patients about the full range of treatment options to help patients make educated decisions regarding their dental care.”

The ADA has supported a class II designation for dental amalgam since 2002 when the FDA first proposed the move, and has since emphasized that numerous studies, including two large clinical trials published in 2006, and others since, support the conclusion that amalgam is a “valuable, viable and safe choice for dental patients”.

But Consumers for Dental Choice called the FDA move “disappointing”, describing it as an “about face” because it did not call for stringent precautions for pregnant women and children.

They informed the media earlier today that last June they filed a court settlement that required the FDA to remove claims about the safety of mercury amalgams from its website and issue an advisory that said:

“Dental amalgams contain mercury, which may have neurotoxic effects on the nervous systems of developing children and fetuses.”

Charles G Brown, National Counsel for Consumers for Dental Choice, said the FDA bowed to the dental products industry and for the first time removed a warning about neurological harm to children:

“FDA broke its contract and broke its word that it would put warnings for children and unborn children for neurological damage.”

“This contemptuous attitude toward children and the unborn will not go unanswered. We will see FDA in court,” said Brown.

The Consumers for Dental Choice statement said:

“The FDA rule destroys a dental myth that the mercury becomes inert in the mouth; FDA says the vapors from dental mercury go into the human body.”

They also said most consumers and most dentists already prefer to use resin composite, which does not contain mercury. Also, they said environmentalists are increasingly targeting amalgam because of mercury waste.

Brown said the FDA was alone in the world for failing to protect children and pregnant women from the dangers of mercury fillings.

Canadian dentists were told in 1996 not to put amalgam in fillings for children and pregnant women, British dentists were told not to do this in 1998 for pregnant women, while Norway and Sweden have banned amalgam altogether, said Brown, who accused the FDA of failing to “carry out its mission of protecting the public health”.

The FDA said the special controls that it is imposing on dental amalgam are in a guide that recommends what should go in it, how to label the product and how to test its performance, among other things.

The FDA controls require that at the very least the label includes:

  • A warning not to use dental amalgam in patients with mercury allergy.

  • A warning telling dentists to use adequate ventilation when handling dental amalgam.

  • A statement discussing the scientific evidence on the benefits and risks of dental amalgam.

  • This discussion should include the risk of inhaled mercury vapor and should help dentists and patients make informed decisions about using dental amalgam.

Sources: FDA, Consumers for Dental Choice, American Dental Association.

Written by: Catharine Paddock, PhD