Dental amalgam, in widespread use for over 150 years, is one of the oldest materials used in oral health care. Its use extends beyond that of most drugs, and is predated in dentistry only by the use of gold. Dental amalgam is the end result of mixing approximately equal parts of elemental liquid mercury (43 to 54 percent) and a metal alloy powder (57 to 46 percent) composed of silver, tin, copper, and sometimes smaller amounts of zinc, palladium, or indium.
Because of a general decline of dental caries because of fluoridation among school children and young adults, the use of dental amalgam began to decrease in the 1970s. There are also changes in patterns of dental caries, largely the result of topical and systematic fluoride, sealant use, improved oral hygiene practices and products and possibly dietary modifications. In 1990, over 200 million restorative procedures were provided in the United States; of these, dental amalgam accounted for roughly 96 million, a 38 percent reduction since 1979.
Carious lesions today are generally smaller, easier to treat, and managed by more conservative treatment that retains tooth structure. Because of the decrease in frequency and size of dental caries, there has been a relative increase in the use of alternative dental restorative materials primarily composite resins. The most commonly used and less expensive of the alternate materials, cannot be used for large fillings because of wear factors and require more frequent replacement. There are currently many serviceable dental amalgam restorations that will need replacing in the future. Approximately 70 percent of the restorations placed annually are replacements. Most of these replacements will require amalgam or other metallic materials, because composite materials often lack sufficient strength or durability to be considered a substitute, but these materials are constantly improving.
Today, dental amalgam is used in the following situations:
Dental amalgam has been used as a dental restorative material for over 150 years. Amalgam remains popular because it is strong, durable and relatively inexpensive. Roughly 200 million restorative procedures performed in 1990 used amalgam. Amalgam use is declining because the incidence of caries is decreasing and because improved substitute materials are now available for certain applications.
Dental amalgam, an inter-metallic compound, contains elemental mercury that is emitted in minute amounts as vapor. Because vapor emitting from amalgam restorations can be absorbed by the patient through inhalation, ingestion, or by other means, concerns have been raised about possible toxicity. At present, there is scant evidence that the health of the vast majority of people with amalgam is compromised, nor that removing amalgam filings has a beneficial effect on health. It also is recognized that a total conversion from dental amalgam to alternative materials would cause a significant increase in U.S. health care costs. Nonetheless, the possibility that this material, as well as currently available alternatives, could pose health risks cannot be totally ruled out because of the paucity of definitive human studies.
Given the limitations of existing scientific data, a research program should be designed and implemented to fill as many gaps as possible in current knowledge about the potential long-term biological effects of dental amalgam and alternative restorative materials. The Public Health Service (PHS) should be a leader in this effort.
The PHS should also educate dental personnel and consumers about the risks and benefits of dental amalgam. An educational program should include information on all restorative materials to help dentists and their patients make informed dental treatment decisions, and encourage dental care providers to report adverse reactions. Such a program should promote the use of preventative measures such as fluoride and dental sealants to prevent caries and thus further reduce the need for dental restorations.
To exert greater control over dental amalgam use, the Food and Drug Administration (FDA) should regulate elemental mercury and dental alloy as a single product. To help dentists identify patients who may exhibit allergic hypersensitivity to all restorative materials, including dental amalgam, the FDA should require manufacturers to disclose the ingredients of these materials in product labeling.
Sweden, Denmark, and Germany have proposed restrictions on dental amalgam use to diminish both human exposure to and environmental release of mercury and not because of any documented health effects associated with exposure to dental amalgam.
The U.S. Public Health Service
believes it is inappropriate at this time to recommend any restrictions
on the use of dental amalgam, for several reasons. First, current scientific
evidence does not show that exposure to mercury from amalgam restorations
poses a serious health risk in humans, except for an exceedingly small
number of allergic reactions. Second, there is insufficient evidence to
assure the public that components of alternative restorative materials
have fewer potential health effects than dental amalgam including allergic-type
reactions. Third, there are significant efforts underway in the U.S. to
reduce the amount of mercury in the environment. And finally, as stated
previously, amalgam use is declining due to a lessening of the incidence
of dental caries and the increasing use of alternative materials.