Dental amalgam controversy

Dental amalgam has had a long history and global impact. Any existence of galvanic pain or association of either currents or mercury to presence of symptoms has been disproven. Very weak currents have been measured in the mouth of those with multiple dental fillings consisting of different alloys, but there was no association between presence of current and symptoms, Claims of causing a variety of symptoms such as oral discomfort, skin irritation, headaches and a metallic taste in the mouth have been discredited. and became well known in Sweden during the 1970s and 80s, because of a campaign to educate about and replace oral amalgam fillings with mercury with other compounds such as ceramic or polymer restorations. 1990s to present In the 1990s, several governments evaluated the effects of dental amalgam and concluded that the most likely health effects would be due to hypersensitivity or allergy. Germany, Austria, and Canada recommended against placing amalgam in certain individuals, such as pregnant women, children, those with renal dysfunction, and those with an allergy to metals. In 2004, the Life Sciences Research Office analyzed studies related to dental amalgam published after 1996 and concluded that mean urinary mercury concentration (μg of Hg/L in urine, HgU) was the most reliable estimate of mercury exposure. It found that those with dental amalgam were unlikely to reach the levels where adverse effects are seen from occupational exposure (35 μg HgU). Some 95% of study participants had μg HgU below 4–5. Chewing gum, particularly for nicotine, along with more amalgam, seemed to pose the greatest risk of increasing exposure. One gum-chewer had 24.8 μg HgU. Studies have shown that the amount of mercury released during normal chewing is extremely low. It concluded that there was not enough evidence to support or refute many of the other claims such as increased risk of autoimmune disorders, but stated that the broad and nonspecific illness attributed to dental amalgam is not supported by the data. Mutter in Germany, however, concludes, "removal of dental amalgam leads to permanent improvement of various chronic complaints in a relevant number of patients in various trials." Hal Huggins, a Colorado dentist (previous to having his license revoked), was a notable critic of dental amalgams and other dental therapies he believed to be harmful. His views on amalgam toxicity were featured on 60 Minutes and he was later criticized as a dentist, "prospecting for disease" and having only an "aura of science" by Consumer Reports. In 1996, a Colorado state judge recommended that Huggins's dental license be revoked, for tricking chronically ill patients into thinking that the true cause of their illness was mercury. Time reported the judge's conclusion that Huggins, "diagnosed 'mercury toxicity' in all his patients, including some without amalgam fillings." Huggins's license was subsequently revoked by the Colorado State Board of Dental Examiners for gross negligence and the use of unnecessary and unproven procedures. == Mercury exposure ==

According to the WHO, all humans are exposed to some level of mercury. According to one dental textbook, eating seafood once a week raises urine mercury levels to 5 to 20 μg/L, which is equivalent to two to eight times the level of exposure that comes from numerous amalgam fillings. Neither exposure has any known health effect. Scientists agree that dental amalgam fillings release elemental mercury vapor, but studies report different amounts. Estimates range from 1 to 3 micrograms (μg) per day according to the FDA. The effects of that amount of exposure are also disputed. Newer studies sometimes use mercury vapor analysis instead of the standard exposure test. Because this test was designed for factories and large enclosures, Consumer Reports has reported that this is not an accurate method of analysis for the mouth. It is less reliable, less consistent, and tends to greatly exaggerate the amount of mercury inhaled. Moreover, it is argued that this test additionally exaggerates the amount of mercury inhaled by assuming that all the mercury vapor released is inhaled. This assumption was reviewed by the U.S. Department of Health and Human Services and not found to be valid. Their research review found that most of the mercury vapor released from amalgam fillings is mixed with saliva and swallowed, some part is exhaled, and the remaining fraction is inhaled. Of these amounts, it is important to note that the lungs absorb about 80% of inhaled mercury. A study conducted by measuring the intraoral vapour levels over 24 hours in patients with at least nine amalgam restorations showed that the average daily dose of inhaled mercury vapour was 1.7 μg (range from 0.4 to 4.4 μg), which is approximately 1% of the threshold limit value of 300 to 500 μg/day established by the WHO, based on a maximum allowable environmental level of 50 μg/day in the workplace. Critics point out that: (1) the workplace safety standards are based on allowable maxima in the workplace, not mercury body burden; (2) the workplace safety numbers do not apply to continuous 24-hour exposure, but are limited to a normal work day and a 40-hour workweek; and (3) the uptake/absorption numbers are averages and not worst-case patients (those most at risk). A test that was done throughout the 1980s by some opposition groups and holistic dentists was the skin patch test for mercury allergies. As part of "prospecting for disease", Consumer Reports wrote that these groups had placed high doses of mercuric chloride on a skin patch, which was guaranteed to produce irritation on the patient's skin and subsequent revenue for the person administering the test. The current recommendations for residential exposure (not including amalgam fillings already accounted for) are as follows: The ATSDR Action Level for indoor mercury vapor in residential settings is 1 μg/m3 and the ATSDR MRL (Minimal Risk Level) for chronic exposure is 0.2 μg/m3 According to the ATSDR, the MRL(Minimal Risk Level) is an estimate of the level of daily exposure to a substance that is unlikely to cause adverse non-cancerous health effects. The Action Level is defined as an indoor air concentration of mercury that would prompt officials to consider implementing response actions. It is a recommendation and does not necessarily imply toxicity or health risks. Breathing air with a concentration of 0.2 μg mercury/m3 would lead to an inhaled amount of approximately 4 μg/day (respiratory volume of 20m3/day). About 80% of inhaled mercury vapor would be absorbed. A 2003 monograph on mercury toxicity from the WHO concluded that dental amalgam contributes significantly to mercury body burden in humans with amalgam fillings and that dental amalgam is the most common form of exposure to elemental mercury in the general population, constituting a potentially significant source of exposure to elemental mercury. Estimates of daily intake from amalgam restorations range from 1 to 12.5 μg/day, with the majority of dental amalgam holders being exposed to less than 5 μg mercury/day. They also note that this will continue to decline as the number of amalgam restorations is declining. == Health research ==

As public pressure demands more research on amalgam safety, an increasing number of studies with larger sample sizes are being conducted. Those who are not opposed to amalgam claim that, aside from rare and localized tissue irritation, recent evidence-based research has continued to demonstrate no ill effects from the minute amounts of mercury exposure from amalgam fillings. Alternative materials Alternative materials which may be suitable in some situations include composite resins, glass ionomer cements, porcelain, and gold alloys. Chelation therapy Anti-amalgam sources typically promote the removal of amalgam fillings and the substitution with other materials. Detoxification may also be advised, including fasting, restricted dieting to avoid mercury-containing foods, and quasi-chelation therapies, allegedly to remove accumulated mercury from the body. The American College of Medical Toxicology and the American Academy of Clinical Toxicology recommend against chelation therapy and say that chelation therapy can artificially and temporarily elevate the levels of heavy metals in the urine (a practice referred to as "provoked" urine testing). They also mention that the chelating drugs may have significant side effects, including dehydration, hypocalcemia, kidney injury, liver enzyme elevations, hypotension, allergic reactions, and mineral deficiencies. Epidemiology Better dental health overall coupled with increased demand for more modern alternatives such as resin composite fillings (which match the tooth color), as well as public concern about the mercury content of dental amalgam, have resulted in a steady decline in dental amalgam use in developed countries, though overall amalgam use continues to rise worldwide. Given its superior strength, durability, and long life relative to the more expensive composite fillings, it will likely be used for many years to come. Over a lifetime, dietary sources of mercury are far higher than would ever be received from the presence of amalgam fillings in the mouth. For example, due to pollution of the world's oceans with heavy metals, products such as cod liver oil may contain significant levels of mercury. Prenatal There is little evidence to suggest that amalgam fillings have any negative direct effects on pregnancy outcomes or on an infant post-pregnancy. A study, consisting of 72 pregnant women, was conducted to determine the effects of dental amalgam on fetuses in utero. Results indicated that although the amount of amalgam the mother had was directly related to the amount of mercury in the amniotic fluid, no negative effects on the fetus were found. A larger study, consisting of 5,585 women who had recently given birth, was used to determine if amalgam restorations during pregnancy had any effects on infant birthweight. Among the study group, 1,117 women had infants with low birth weights and 4,468 women had infants with normal birth weights. Approximately five percent of the women had one or more amalgam filling restorations during their pregnancy. These women had little to no difference in infant birth weight compared to the women who did not undergo amalgam restoration during pregnancy. Public awareness A 2006 Zogby International poll of 2,590 US adults found that 72% of respondents were not aware that mercury was a main component of dental amalgam and 92% of respondents would prefer to be told about mercury in dental amalgam before receiving it as a filling. A 1993 study published in FDA Consumer found that 50% of Americans believed fillings containing mercury caused health problems. Some dentists (including a member of the FDA's Dental Products Panel) suggest that there is an obligation to inform patients that amalgam contains mercury. A prominent debate occurred in the late 20th century, with consumer and regulatory pressure to eliminate amalgam being "at an all-time high". In a 2006 nationwide poll, 76% of Americans were unaware that mercury is the primary component in amalgam fillings, and this lack of informed consent was the most consistent issue raised in a recent U.S. Food and Drug Administration (FDA) panel on the issue by panel members. The broad lack of knowledge among the public was also displayed when a December 1990 episode of the CBS news program 60 Minutes covered mercury in amalgam. This resulted in a nationwide amalgam scare and additional research into mercury release from amalgam. The following month Consumer Reports published an article criticizing the content of the broadcast, stating that it contained a great deal of false information and that the ADA spokesperson on the program was ill-prepared to defend the claims. For example, 60 Minutes reported that Germany was planning to pass legislation within the year to ban amalgam, but the Institute of German Dentists said one month later that there was no such law pending. Also, one physiologist interviewed by Consumer Reports noted that the testimonials are mostly anecdotal, and both the reported symptoms and the rapid recovery time after the fillings are removed are physiologically inconsistent with that of mercury poisoning. Consumer Reports goes on to criticize how 60 Minutes failed to interview the many patients who had fillings or teeth removed, only to have the symptoms stay the same or get worse. In 1991, the United States Food and Drug Administration concluded, "none of the data presented show a direct hazard to humans from dental amalgams." In 2002, a class action lawsuit was initiated by patients who felt their amalgam fillings caused them harm. The lawsuit named the ADA, the New York Dental Association, and the Fifth District Dental Society for deceiving "[the] public about health risks allegedly associated with dental amalgam." On 18 February 2003, the New York Supreme Court dismissed the two amalgam-related lawsuits against organized dentistry, stating the plaintiffs had "failed to show a 'cognizable cause of action'". Research directions The proper interpretation of the data is considered controversial only by those opposed to amalgam. The vast majority of past studies have concluded that amalgams are safe. However, although the vast majority of patients with amalgam fillings are exposed to levels too low to pose a health risk, many patients (i.e. those in top 0.1%) exhibit urine test results which are comparable to the maximum allowable legal limits for long-term work place (occupational) safety. Two recent randomized clinical trials in children discovered no statistically significant differences in adverse neuropsychological or renal effects observed over five years in children whose caries were restored using dental amalgam or composite materials. In contrast, one study showed a trend of higher dental treatment need later in children with composite dental fillings, and thus claimed that amalgam fillings are more durable. However, the other study (published in JAMA) cites increased mercury blood levels in children with amalgam fillings. The study states, "during follow-up [blood mercury levels were] 1.0 to 1.5 μg higher in the amalgam group than in the composite group." EPA considers high blood mercury levels to be harmful to the fetus and also states, "exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages." Currently, the EPA has set the "safe" mercury exposure level to be at 5.8 μg of mercury per one liter of blood. While mercury fillings themselves do not increase mercury levels above "safe" levels, they have been shown to contribute to such an increase. However, such studies were unable to find any negative neurobehavioral effects. ==Environmental impact==

Environmental concerns over external costs exist as well. In the United States, several states, including New Jersey, The WHO reported in 2005 that in the United Kingdom, mercury from amalgam accounted for 5% of total mercury emissions. == Organizational statements ==

American Dental Association (ADA) The American Dental Association (ADA) has asserted that dental amalgam is safe and has held, "the removal of amalgam restorations from the non-allergic patient for the alleged purpose of removing toxic substances from the body, when such treatment is performed solely at the recommendation or suggestion of the dentist, is improper and unethical". of the Medical Devices Advisory Committee, the ADA supports the 2009 FDA ruling on dental amalgam. The ADA asserts the best scientific evidence supports the safety of dental amalgam. The FDA concluded that individuals age six and older are not at risk of mercury-associated health effects from mercury vapor exposure that come from dental amalgam. == Regulation ==

Mercury in dental fillings is considered safe and effective in all countries practicing modern dentistry (see below). There are currently two countries, Norway and Sweden, that have introduced legislation to prohibit or restrict use of amalgam fillings; however, in both cases amalgam is part of a larger program of reducing mercury in the environment and includes the banning of mercury-based batteries, thermometers, light bulbs, sphygmomanometers, consumer electronics, vehicle components, etc. In many countries, unused dental amalgam after a treatment is subject to disposal protocols for environmental reasons. Over 100 countries are signatories to the United Nations "Minamata Convention on Mercury". The British Dental Association has worked with the Council of European Dentists to prevent an immediate ban of amalgam until further research into practicalities has been undertaken, which is currently ongoing. The European Commission will report to European Parliament by June 2020, and to the European Council by 2030 regarding the viability of ending dental amalgam use by 2030. Japan In Japan, the use of amalgam began to decline around the 1990s; since 2016, fillings with amalgam alloys have been excluded from insurance coverage. Amalgam is still allowed as of 2023, but is rarely used because it is very expensive. Dental composite and palladium alloys are used instead. ==See also==