Government and Professional Organization
Policy Statements on Dental Amalgam
FDA's Position on Mercury in Dental Amalgams
October 22, 1990
The Food and Drug Administration has reviewed recent research performed in sheep in which it was shown that small amounts of mercury vapor could be released from dental amalgams and absorbed into various organs of the animal's body. Although laboratory studies of this kind are useful in that they raise preliminary questions about the safety of dental amalgams, they also leave other important questions unanswered. For example, because of basic differences in the anatomy and physiology of sheep and humans, it is unknown whether similar levels of mercury would be released in the human mouth, or whether human organs would absorb the released mercury in the same way as sheep. Assuming that a minute amount of mercury may be released from dental amalgams in humans, the question remains as to how much is released and absorbed, and, more importantly, whether this amount of mercury has any bearing on human health.
Until these questions are answered and we have reasonable evidence that dental amalgams actually can be harmful to health, we cannot take action against these products, particularly in light of the value they provide in dental care. In order to get the answers concerning potential risk we will continue to monitor and evaluate the international research in this areas (including yet-unpublished studies which have been cited in the news media concerning fetal exposure to mercury from the mother's dental amalgams). We will also raise the issue of possible hazards from dental amalgams at the next meeting of our Dental Products Panel, an advisory committee of outside experts, and get their recommendations.
If research shows that the use of dental amalgams can pose a risk to patients, FDA has several options, including removing them from the market. But we cannot exercise these options without sound scientific evidence that there is a risk.
American Dental Association Statement on Dental Amalgam
Historically, dental caries has been the most widespread disease known to mankind. For over 150 years, dental amalgam has been the principal restorative material used to treat dental caries and restore patients to good oral health. As a result, many people today retain their natural dentition. Without the benefit of amalgam restorations, they would be partially or completely without their teeth. Throughout its use, there has been considerable scientific study of amalgam and no documented evidence to support the contention that amalgam, or the mercury contained in amalgam, has any deleterious effect on the health or physical well-being of the millions of patients served throughout the world.
The dental profession is committed to providing the best service to the public in a safe manner at a reasonable cost. At the present time, available alternative materials are either significantly more costly or have so far failed to demonstrate comparable strength, durability, or compatibility in the oral environment.
Banning dental amalgam would be financially advantageous to dental practitioners, since its replacement would necessitate the use of other, more costly materials and procedures. It also would be a disservice to those patients who would be denied the benefits of dental care because of prohibitive cost. Any replacement of existing amalgam restorations would be both costly and impose considerable risk to otherwise healthy teeth. The ADA thus continues to believe that dental amalgam should remain available as a safe and effective treatment.
The dental profession is committed to continuous improvement in the delivery of oral health care. During the past 50 to 75 years when dental caries was extremely common, massive amounts of amalgam were used to restore teeth. During the early years, the mercury-to-alloy ratio of amalgam was in the range of eight parts of mercury to 5 parts of other materials, compared to its current formulation of much less than 1:1. During that period, because caries was so prevalent and technology was still in its infancy, cavity preparations were large and extensive amounts of amalgam were used in each preparation, with no evidence of deleterious effect on the health or physical well-being of patients. Today, it is even less likely that any such effect would be seen. Dental decay has declined significantly, as evidenced by the fact that nearly half of Americans achieve the age of 17 without experiencing any dental caries. Technology has improved as well; preparations are more conservative and alloys with much lower mercury content are now being used routinely. As a result, the amount of amalgam used today is but a fraction of that used as recently as 15 years ago.
The ADA has consistently supported research in the development of new materials that will equal or exceed the benefits of amalgam at a cost that will not be prohibitive to the average person.
The ADA has also welcomed over the years the considerable research that has been done on dental amalgams. Overwhelmingly, this research has led the scientific community to support amalgam as a safe restorative material. The research currently creating interest and controversy has been found by the scientific community to have considerable shortcomings in methodology and to be totally inconclusive as to any detrimental health ramifications for humans.
The ADA will continue to support further scientific inquiry and welcomes the amalgam review planned by the Food and Drug Administration and the materials safety workshop scheduled by the National Institute of Dental Research (NIDR). The ADA further strongly urges NIDR to fund the grant proposal pending for a major epidemiological study of humans with dental amalgams.
Based on the research and epidemiological evidence available to date, the ADA continues to support dental amalgam as a safe and effective restorative material and sees no cause for public concern about either existing or future amalgam restorations.
Amalgam - General Recommendations - Sweden
At present, there are no scientific data indicating that exposure to mercury from dental amalgam causes symptoms of poisoning. The National Board of Health and Welfare's group of experts, however, underlined that amalgam is an unsuitable dental filling material from a toxicological point of view. The development should be stimulated of new dental filling materials which are technically and biologically toxicologically satisfactory. While waiting for such materials to become available as general replacement for amalgam, amalgam may therefore still be used as dental replacement material.
On the other hand, the Board of Health and Welfare is of the opinion that treatment of pregnant women with amalgam should be avoided as far as possible. This judgment has been passed awaiting further research into disorders of the reproductive system related to exposure to mercury.
Dentists shall always inform the patient about possible alternatives and take notice of the patient's right to refuse certain treatment.
The Board of Health and Welfare recommends that all handling of mercury and mercury compounds be done in such a way that both individual exposure and contamination of the environment is reduced to the lowest possible level. The use of amalgam should be gradually decreased. Alternatives like composite materials or glass ionomer cements are today considered the best when reparative treatment of small caries lesions is carried out. These alternatives should be used as far as possible in such treatment and also in other cases where it is considered indicated and when for various reasons other alternatives cannot be applied.
Polishing of and drilling in amalgam should always be done with water cooling and by using high-speed water evacuation in order to reduce exposure to mercury vapour.
Patients who have developed contact allergy against mercury should have their existing amalgam fillings exchanged for other material. This also applies to patients with lichen planus or lichenlike reactions in connection with amalgam fillings.
These general recommendations will be renewed as and when further research results appear.
The National Board of Occupational Safety and Health will publish recommendations on how to handle amalgam and mercury at dental clinics.
Use of Amalgam Limited - Federal Public Health Office Provides Guidelines- Germany
The manufacturers' instructions for the use of amalgams by dentists are to be changed by order of the Federal Public Health Office according to latest scientific findings. From now on, amalgams are to be used solely for areas exposed to mastication (molar teeth). Additionally, only gamma-2-free amalgams are to be used. The Federal Public Health Office intends to call back the approval for gamma-containing amalgams, mainly because of the poorer quality of these materials.
The Federal Public Health Office has worked out guidelines for the use of amalgams under the newly specified conditions in dental therapy. These guidelines provide answers to the most important questions and are available to the public. The guidelines are addressed to dentists, patients, and general practitians likewise. The guidelines come in an information booklet with the title: "Amalgams in Dental Therapy" and can be requested at no charge from "Institut fur Arzneimittel des Bundesgesundheitsamtes" Seestrasse 10, W-1000, Berlin 65.
According to the latest status of scientific knowledge no reasonable suspicions that amalgam fillings are hazardous to one's health can be established from a medical point of view if one considers the already existent burden of mercury through a person's daily intake of mercury with food, water and air. Nevertheless, the use of amalgams is to be decreased as much as possible in order to reduce the strain on the human body caused by general mercury intake.
In the opinion of the Federal Public Health Office, amalgam is a means for operative dentistry on molar teeth (areas exposed to mastication) only. The Federal Public Health Office recommends the use of alternative materials for front teeth or areas that are not mainly used for mastication. Which one of the alternative materials is to be chosen depends entirely on the individual medical situation. This question should be settled between dentist and patient.
The Federal Public Health Office does not recommend to substitute already existing filling by other filling materials, unless the individual medical situation, e.g., an allergic reaction, requires that.
Patients with kidney problems should not have their cavities filled with amalgarns. Also, the use of amalgams should be very carefully considered for children under the age of 6, especially up to 3 years, since the sensitivity to mercury is said to be highest at early age.
As already recommended in 1987 by the Federal Public Health Office, no major dental procedures involving amalgams should be done during pregnancy. Even though there are no reasons to believe that amalgams could be hazardous to the health of the unborn child, the Federal Health Office asks to observe this recommendation in the interest of preventive medicine.
By financially supporting scientific projects dealing with amalgams' potential hazards to the human health, the Federal Public Health Office has helped to gain new scientific knowledge in this matter.
Even in comparison to other comparable countries, these new recommendations for the use of amalgams in Germany represent a considerable restriction. The new recommendations are in substance being supported by the Pharmaceutic Commission of Dentist. The elimination of the use of amalgams provides that alternative filling materials are available. The Federal Public Health Office thinks that priority to research in this particular field is extremely necessary especially on the part of pharmaceutical companies.
Federation Dentaire Internationale Policy Statement on Mercury and Silver Amalgam in Dentistry
1.0 - Safety of silver amalgam:
Silver amalgam (an amalgam of mercury, silver, copper and tin) has been used in dentistry for over 150 years as a safe and effective restorative material to replace lost tooth structure. Experience with this material has extended for over 150 years. Notwithstanding the mercury component of silver amalgam, extensive reviews of the scientific literature have not revealed any data published in refereed scientific journals to support claims that amalgam restorations have caused any adverse biological reactions other than extremely rare allergy to one of the amalgam components. Localized lichenoid reactions of the oral mucosa may occur adjacent to amalgam restorations similar to reactions which may occur adjacent to any restoration.
2.0 - Risk of mercury hypersensitivity:
It is recognized that a very small proportion of the population may have an allergy attributable to mercury and only very few of these individuals react to amalgam restorations. Such an allergy needs to be demonstrated by recognized methods by a specialist allergist. Biological reaction to mercury is most likely to be seen as oral (lichenoid) lesions adjacent to silver amalgam restorations.
Where a hypersensitivity to mercury can clearly be demonstrated by accepted means placement of silver amalgam restorations should be avoided. The use of mercury detectors for routine measurement of mercury vapour is not advocated as a standard test for mercury toxicity. Galvanic current measurement techniques are not an accepted method for the purpose of testing for toxicity at a cellular level.
3.0 - Mercury sources:
Mercury intake occurs from sources which include mercury in air, and from industry, dentistry, and some medications. Mercury occurs in three forms.
3.1 Elemental mercury
Exposure to elemental mercury is usually occupational and arises from vapour inhalation. Mercury vapour is almost completely absorbed and oxidized to the inorganic forms.
3.2 Inorganic mercury
Particles of silver amalgam are inorganic mercury compounds. Inorganic mercury if ingested, is poorly absorbed from the gut. It is present in some food and medications. Following reaction with the gastric juices absorption occurs, however, such mercury tends to remain in the inorganic state whereby it is readily excreted in urine. There is no significant conversion of inorganic to organic mercury compounds in the body.
3.3 Organic mercury
Organic mercury, which is highly toxic, originates from food, particularly seafood from contaminated waters. Organic mercury may also originate from some pesticides and agricultural herbicides. Organic mercury is readily taken up by the body. Inorganic mercury is not converted to organic mercury in the body in significant amounts.
4.0 - Food as a source of mercury:
There is a substantial intake of mercury from food, mainly fish and seafood. The contribution to the body burden of mercury from silver amalgam restorations is relatively small in comparison with that from regular food sources. Further, the amount of mercury exposure due to silver amalgam does not appear to be hazardous.
5.O - Dental clinical personnel and occupational exposure to mercury:
Dental clinical personnel when using silver amalgam should exercise proper procedures to avoid personal contact with mercury. Precautions should be taken to avoid exposure to mercury vapour in the dental environment and waste amalgam should be collected for disposal in a manner which will protect those who handle the waste, and the environment.
6.0 - Replacement of amalgam restorations not justified:
Replacement of silver amalgam restorations is not justified except when the restoration has failed; where it has fractured; where there is recurrent dental caries at its margin; where access to the dental pulp is needed; or where there is clearly-established case of mercury hypersensitivity associated with clear evidence of an adverse effect from an amalgam restoration.
The Food and Drug Administration of the United States of America in a statement made in March 1991 advises individuals against having their amalgam restorations removed.
7.0 - Silver amalgam alternatives:
Where alternative restorative materials to silver amalgam are used, consideration must be given to their potential adverse effect, both local and systemic, and also to the physical properties needed to meet the requirements of a dental restorative material.
8.0 - Materials research:
Research into and development of dental materials which could be used as alternatives to amalgam should continue and be encouraged.
9.0 - The invasive nature of all restorative procedures:
No restoration of a damaged tooth is made without inconvenience and some risk however slight. Restoration of teeth is an invasive procedure, and there are risks, however slight, associated with restorative materials and their manipulation, and with drugs such as local anesthetics required for the restorative procedure. As well, restoration of tooth structure lost through dental decay, trauma, or other causes, requires a lifelong commitment to maintenance of the restoration
10.0 - Dental caries prevention reduces need for restorations:
Where preventive dentistry programs with fluoridation of public water supplies have been employed, they have greatly reduced dental decay. Any risk that could arise from dental restorative materials or techniques used for their placement is thus lessened by reduced dental caries through preventive means such as fluorides and sealants. The role of noninvasive treatment of early carious lesions in reducing the need for restorations is also recognized.
Environmental Contamination From Mercury: Relationship to Recommendations Concerning Amalgam Use in Europe and United States
During the 1950's and 1960's, the world began to recognize the consequences of uncontrolled release of mercury into the environment. The most widely known episode, involving release of large quantities mercury into Minamata Bay Japan, from 1953 through the early 1960's caused methylmercury poisoning in hundreds of people who ate seafood from the bay. Later Sweden, other European countries, and the United States identified significant mercury releases from chloralkali plants and pulp-paper plants. Since the early 1970's various countries have made continuing but inconsistent effort to reduce the release of mercury into the environment.
Draft order for the discontinuation or mercury use in Denmark
In June 1989, the Danish government issued a draft order that would ban the import and sale of mercury and products containing mercury. The order included several deadlines for discontinuing the use of mercury and mercury compounds, including the use in oral thermometers, on seeds, in laboratories, and in dental amalgam.
However, because officials did not reach a policy decision concerning the draft order these deadlines have passed without compliance. Dental amalgam reportedly accounts for the single largest use of mercury in Denmark. (Grandjean, Phillipe, Institute of Community Health, Odense University, Odense, Denmark, personal communication November 3, 1992.)
Consideration of discontinuation of mercury use - Sweden
For environmental reasons, within the last year the Swedish Parliament approved a general plan to discontinue the use of mercury in that country. The National Chemical Inspectorate (NCl) and the Swedish Environmental Protection Agency (SEPA) developed suggestions about how the discontinuation should take place region by region. The government commissioned the National Board of Health and Welfare to study the requirements for discontinuing the use of mercury-containing amalgam for dental restorations. Although dental amalgam is but one use of mercury that contributes to the release of mercury into the environment, as other uses of mercury are curtailed, the mercury used in dentistry will account for a larger fraction of the total mercury released. In Sweden, the SEPA estimates that about one-third of the mercury found in waste-water sludge now comes from dental amalgam.
The investigation team of the Swedish National Board of Health and Welfare was asked to outline a possible stepwise plan for discontinuing the use of dental amalgam. The fist step is to discontinue the use of amalgam in children's temporary teeth after July 1, 1993. The second step is to discontinue the use of amalgam in the permanent teeth of children and teenagers up to the age of 19 after July 1, 1995. The plan also emphasized the potential side effects and increased costs of the alternative materials. It was also recognized that the need for amalgam restorations in these age groups of the Swedish population are minimal.
The investigation team also believed that the use of amalgam fillings could possibly be stopped for adults starting in 1997. Before such a decision is made, however, the team recommended that the effects of amalgam use and the costs of available alternatives should be evaluated. The team also recommended assessing to what extent future dental care insurance will allow patients to choose a more expensive alternative. A decision about whether to discontinue the use of amalgam restorations for adults should be made in 1996.
Environmental contamination - United States
Within the last 10 years, fish samples from some lakes and streams around the United States have shown concentrations of mercury sufficient for the responsible state agencies to issue fish advisories. According to results of a 1989 survey, 33 states had issued fish advisories because of heavy metals, 17 because of mercury. Since that time, at least three other states have issued fish advisories because of mercury contamination and another is in the process of writing such an advisory. Initial evaluations of the fish data led to a theory that the mercury contamination of fish was caused by acidification of the water from acid deposition with resulting release of mercury from the soil. However, as the mercury contamination of fish was observed increasingly around the country, it was thought that the problem was not due to acid deposition but primarily to mercury deposition. One example is illustrated by the State of Michigan Department of Natural Resources, June 24, 1992, draft report entitled, "Mercury in Michigan's Environment: Causes and Extent of the Problem" which gives an estimate of air emissions of mercury in Michigan for 1989. The contribution of dental mercury was about 1.8 percent of the total.
Efforts to reduce release of mercury - United States
Within the last several years, the U.S. Environmental Protection Agency (EPA) has become concerned about the release of mercury into the environment. As a result, EPA, together with the manufacturing industry, established a voluntary program for waste release reduction known as the 33/50 program. Its goal is to reduce the discharge of mercury and 16 other chemicals 33 percent by 1992 and 50 percent by 1995. These reductions are from base levels established by the 1988 toxic release inventory (TRI) data. Data from the Environmental Protection Agency show that mercury disposal in United States increased by more than 65 percent from 1970 to 1989 (1). That data also show that efforts to reduce the use and disposal of mercury projects a more than 75 percent reduction in mercury disposal by the year 2000. Disposal of mercury from the use of dental amalgam is projected to account for about 1.3 percent of the total for the year 2000, about the same percentage as in 1980.
In Title III of the Clean Air Act Amendments of 1990, section 112(n)(1)(B), Congress mandated that the Administrator of EPA,
"shall conduct, ... a study of mercury emissions from electric utility steam-generating units, municipal waste-combustion units, and other sources, including area sources. Such study shall consider the rate and mass of mercury emissions, the health and environmental effects of such emissions, technologies which are available to control such emissions, and the costs of such technologies."
EPA has until November 1994 to complete the study and deliver the report to Congress. Future legislation and regulation, if any, will depend upon the findings of this study.
Amalgam's contribution of mercury to body burden
Most data suggest that the daily mercury dose is 1 to 5 µg higher for subjects with 7 to 10 amalgam dental restorations than for persons with none. Clarkson and colleagues (2) estimated that for the general U.S. population "the dominant exposure (for elemental mercury) is to mercury vapor from dental amalgams." In low-level occupational exposures, the subclinical health effects detected have occurred in groups with mean tissue mercury levels that are 10 times higher than those of the general population; however, the relationship between the observed effects and the tissue levels is not clear.
German and Swedish recommendations on amalgam use during pregnancy
In 1987, Germany's Federal Health Agency (Bundesgesundheitsamt, BOA) recommended that major procedures involving amalgam restorations should not be done during pregnancy. In 1988, the National Board of Health and Welfare of Sweden recommended that if possible, amalgam should not be used in the treatment of pregnant women. Neither of these pronouncements was based on medical evidence of reproductive health effects in humans. Rather, they were based on two observations: 1) that inhaled mercury vapor crosses the placenta and 2) that there is a 1-month spike in mercury concentration in the blood of a patient who has had an amalgam restoration placed or removed. Thus, these recommendations were made so as to prevent subjecting the child to an additional mercury exposure during the time of greatest development. It should be noted that the pregnancy restriction was recommended to be reversed by the Swedish Medical Research Council, April 1992, because of lack of scientific evidence. (Sundberg, Hans, Chief Dental Officer, National Board of Health and Welfare, Stockholm, Sweden, personal communication, November 3, 1992) It is generally considered prudent practice in dentistry and medicine to limit most drugs or extensive procedures during pregnancy because of the unknown effects on the developing child.
Restriction on use of amalgam - Germany
Early in 1992, the BGA developed guidelines for the use of amalgam. One of these withdrew gamma-2-amalgam from the market because of its poorer physical properties (gamma-2-amalgam is not used in the United States). Another requires manufacturers' instructions to dentists to limit amalgam's use solely to tooth areas exposed to mastication. While issuing the new guidelines, the BGA stated:
"According to the latest status of scientific knowledge, no reasonable suspicions that amalgam restorations are hazardous to one's health can be established from a medical point of view if one considers the already existent burden of mercury through a person's daily intake of mercury from food, water, and air." (3)
The reason given for the limitation imposed by the new guideline was:
"...the use of amalgam is to be decreased as much as possible in order to reduce the strain on the human body caused by general mercury intake." (2)
The European countries that have proposed or recommended restrictions on the use of dental amalgam have done so in an effort to diminish both human exposure to and environmental release of mercury and not because of any documented health effect associated with exposure to dental amalgam.
There are no credible scientific studies which show that exposure to mercury from amalgam dental restorations causes disease in humans, other than allergic response in a small segment of the population.
In studies of low-level occupational exposures, the subclinical effects detected have occurred in groups with mean tissue mercury levels that are only 10-fold higher than those of the general population; however, the relationship between the observed effects and the tissue levels is not clear.
Significant efforts are under way in the United States to reduce the amount of mercury released into the environment. These efforts may intensify following EPA's report to Congress due in November 1994.
Based on experiences with lead exposure, it would be prudent to minimize human exposure to all heavy metals—including mercury. With the efforts under way to reduce mercury use and disposal, the continued use of mercury in dental restorations -will account for an increasing percentage of the total exposure to mercury for those with amalgam dental restorations. However, its health significance may decline as reductions in other environmental mercury exposures results in a decline in overall mercury exposure.
Amalgam has been used in the United States for 150 years and has been used in over 100 million dental restorations per year for the last 20 years or more, with no scientifically documented health effects, except allergic reactions affecting a small segment of the population. This lack of documented health effects cautions against a hasty decision to replace amalgam with alternative materials about whose potential health effects from long-term, low-level exposure are not well documented.
Because no credible scientific studies show that exposure to mercury from amalgam dental restorations causes disease in humans, except for allergic reactions affecting a small segment of the population, there is no health-based reason for the Public Health Service to restrict the use of amalgam for dental restorations.
In order to reduce human exposure to mercury from dental amalgam restorations, the U.S. Public Health Service is implementing an expanded and targeted research program to develop alternative dental restorative materials for which we understand the health consequences of long-term, low-level exposure.
1. Palmer C. Amalgam declining as a source of Hg in Trash, American Dental Association News, 1992 Oct 5: page 12, col 1.
2. Clarkson TW, Hursch JB, Sager PR, Syversen TLM. Mercury. In: Clarkson TW, Friberg L, Nordberg GF, and Sager PR, ed. Biological Monitoring of Toxic Metals. New York: Plenun Press, 1988: 199-246.
3. Translation of the announcement in BGA Pressedienst, February 5, 1992.