The dental amalgam controversy is a debate over the use of mercury amalgam as a dental filling. Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum Amalgam is a commonly used dental filling that has been used for over 150 years A dental restoration or dental filling is a Dental restorative material used artificially to restore the function integrity and morphology of missing tooth The concern centers around the long-term health effects of toxicity or allergy which may be associated with constant mercury exposure, particularly as a potential cause of chronic illnesses, autoimmune disorders, neurodegenerative diseases, birth defects, and mental disorders. In Medicine, a chronic disease is a Disease that is long-lasting or recurrent Autoimmunity is the failure of an organism to recognize its own constituent parts as self, which results in an immune response against its own cells and tissues Neurodegenerative Disease ( Greek νέυρο- néuro-, "nerval" and Latin dēgenerāre, "to decline" or "to A congenital disorder is a disease or disorder that is present at birth Mental disorder or mental illness is a psychological or behavioral pattern that occurs in an individual and is thought to cause distress or disability that is not expected as Scientists agree that mercury amalgam fillings expose the bearers to a daily dose of mercury, but different studies have concluded that this exposure may be as low as 1-3 µg/day (FDA), or as high as 27 µg/day (Patterson). 
Peer-reviewed scientific studies have come to opposite conclusions on whether mercury exposure resulting from amalgam fillings is a cause of health problems. For example, a 2004 literature review conducted by the Life Sciences Research Office, whose clients include the FDA and NIH, and which has "a reputation for taking on politically-charged issues", concluded that, "The current data are insufficient to support an association between mercury release from dental amalgam and the various complaints that have been attributed to this restoration material". A literature review is a body of text that aims to review the critical points of current Knowledge on a particular topic Life Sciences Research Office (LSRO is a Non-profit organization based in Maryland US that specializes in assembling ad hoc expert panels to  A 2005 risk assessment published by the Freiburg University Institute for Environmental Medicine found that "mercury from dental amalgam may lead to nephrotoxicity, neurobehavioural changes, autoimmunity, oxidative stress, autism, skin and mucosa alterations or non-specific symptoms and complaints", that "Alzheimer's disease or multiple sclerosis has also been linked to low-dose mercury exposure", and that "removal of dental amalgam leads to permanent improvement of various chronic complaints in a relevant number of patients in various trials. Nephrotoxicity (from Greek nephros "kidney" is a Poisonous effect of some substances both Toxic chemicals and Medication, on the Kidney Autoimmunity is the failure of an organism to recognize its own constituent parts as self, which results in an immune response against its own cells and tissues Language development. The terminology Alzheimer's disease ( AD) also called Alzheimer disease or simply Alzheimer's, is the most common form of Dementia. Multiple sclerosis (abbreviated MS also known as disseminated sclerosis or encephalomyelitis disseminata) is an autoimmune condition in which the "
Potential amalgam-induced health risks which have been studied by researchers include those related to allergy as well as toxicity. In 2002, the Food and Drug Administration issued a statement on dental amalgam which asserted that "no valid scientific evidence has shown that amalgams cause harm to patients with dental restorations, except in the rare case of allergy".  A 1991-1997 study of 3162 patients in Sweden and Germany found that 719 of them, or 23 percent, had positive results for systemic allergic sensitivity to inorganic mercury on the MELISA lymphocyte proliferation test.  In a smaller group of 85 patients who suffered from symptoms resembling Chronic Fatigue Syndrome and had their amalgams replaced with composites and metal-free ceramics, "over 78 percent reported improvement in health status as compared to the period prior to metal removal. Chronic fatigue syndrome ( CFS) is the most common name given to a poorly understood variably debilitating disorder or disorders of uncertain causation " A paper published as part of a 1991 National Institutes of Health conference on side-effects of dental restorative materials reported a 22. "NIH" redirects here For other meanings of NIH see NIH (disambiguation. 53% incidence of allergy in subjects who had amalgam fillings for more than five years.  As recently as 2004, the ADA claimed that there had been less than 100 reported cases of allergic reactions to amalgam filings. 
The American Dental Association (ADA) has asserted that dental amalgam is safe since its foundation in 1859. The American Dental Association (ADA is an American Professional association established in 1859 and has more than 152000 members In its advisory opinion to Rule 5. A. of the ADA Code of Ethics, it has also held that, "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 of suggestion of the dentist, is improper and unethical".  According to the Boston College Law School study, "A dentist who is found guilty of violating the ADA Code of Ethics can be sentenced, censured, suspended, or expelled from the ADA" and the "ADA forbids its dentists from suggesting mercury removal under threat of license suspension".  The same study pointed out that state dental associations and disciplinary boards have "not only adopted the ADA's position as a matter of routine" in proceedings which have sanctioned anti-amalgam dentists or stripped them of their licenses in California, Maryland, Arizona, Colorado, and Minnesota, but in many cases "the board members themselves often belonged to the ADA as well".  A 2002 article in the Atlanta Journal and Constitution reported allegations by anti-amalgamists that the ADA had effectively imposed gag rules which forbade them from discussing their positions with patients. The Atlanta Journal-Constitution is the only major daily Newspaper in Atlanta Georgia, USA and its suburbs.  The Boston College Law School study also cites proceedings in which an Arizona dentist, "is facing sanctions for advocating alternative materials", a California dentist lost his license, "for running an advertisement entitiled: "Mercury Emission from Silver Filings Unsafe by Government Standards", and a Maryland dentist, "was sanctioned for writing an article on mercury amalgam removal".  More recently, the ADA has entered into litigation "aimed at defending its reputation and discouraging further lawsuits by patient-plaintiffs against mercury amalgam". 
According to a 2006 Zogby International poll of 2,590 US adults, 72% of respondents were not aware that mercury was the 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. John Zogby (born 1948) is an American political pollster and first senior fellow at The Catholic University of America 's Life Cycle Institute  A 1993 study published in FDA Consumer found that 50% of Americans believed mercury filings caused health problems.  Some dentists, including one member of the FDA's Dental Products Panel, have suggested that the desire among patients to be informed concerning the materials used in their restorations, together with the perception that there are risks associated with mercury filings among half of the US population, obligates dentists to apply the doctrine of informed consent by notifying their patients that amalgam contains mercury. Informed consent is a legal condition whereby a person can be said to have given Consent based upon an appreciation and understanding of the facts implications  On the other hand, because state dental boards have relied on the ADA's position concerning amalgam safety in sanctioning dentists with opposing views, dentists who wished to provide their patients with informed consent concerning this controversy might reasonably fear that they would face loss of their licenses.
In addition to health concerns, opponents to mercury amalgam fillings point to the negative externalities of water contamination and environmental damage of mercury, especially since its use by dentists goes largely unregulated. In Economics, an externality is an impact on any party not directly involved in an economic decision
Dentists who advocate the use of amalgam point out that it is durable. , cheap, and easy to use. On average, resin composites last only half as long as mercury amalgam, although more recent studies find them comparable to amalgam in durability, and porcelain is much more expensive. Dental composites, also called white fillings, are a group of restorative materials used in dentistry Porcelain is a Ceramic material made by heating raw materials generally including Clay in the form of Kaolin, in a Kiln to temperatures However, the gap between amalgam and composites may be closing.  Further, concerns have been raised about the estrogen-mimicking effects of the plastic chemicals used in composite resins such as Bisphenol A used . Bisphenol A, commonly abbreviated as BPA, is an Organic compound with two Phenol Functional groups It is a difunctional building block of 
Dental amalgam has been found to continuously vaporize to mercury vapor in the mouth. Amalgam is a commonly used dental filling that has been used for over 150 years The World Health Organization notes that exposure can be greatly increased by personal habits such as bruxism or gum-chewing, and cites a report which found a 5. Bruxism (from the Greek βρυγμός (brugmós gnashing of teeth) is the grinding of the teeth and is typically accompanied by the clenching 3 fold increase in mercury levels after chewing, eating, or toothbrushing. They report that amalgam is estimated to contribute 50% of mercury exposure in adults. In the studies the WHO reviews, daily mercury exposure estimates range from 3 μg/day to 9 μg/day.  Separately the World Health Organization reports that "there may be no level of mercury at which some adverse effects do not occur", that mercury from amalgam and laboratory devices accounts for 53% of total mercury emissions, and that one-third of the mercury in the sewage system comes from dental amalgam. 
A study conducted by measuring the intraoral vapor levels over a 24-hour period in patients with at least nine amalgam restorations showed the average daily dose of inhaled mercury vapor was 1. 7 µg (range from 0. 4 to 4. 4 µg), which is approximately only 1% of the threshold limit value of 300 to 500 µg/day established by the World Health Organization, based on a maximum allowable environmental level of 50 µg/day in the workplace.  However, a doctor's reference shows that the average person with amalgam fillings has approximately 10 times the mercury burden of a person without. 
A Swedish study of autopsies examined the mercury levels in brains and kidneys and found a strong correlation with the number of amalgam fillings.  A German study found that mercury urinary excretion was significantly higher in those with mercury amalgam fillings. 
The Fédération Dentaire Internationale performed a meta-analysis of the literature on mercury toxicity and concluded that there is no documented scientific evidence to show adverse effects from mercury in amalgam restorations except in extremely rare cases of mercury hypersensitivity. 
In response to studies which assert amalgam safety, anti-amalgam groups, such as the International Academy of Oral Medicine and Toxicology (IAOMT), state that these studies are poorly designed and raise ethical questions. The International Academy of Oral Medicine and Toxicology is formally chartered as a Canadian non-profit corporation representing dental medical and research professionals An analysis of the data collected during the studies showed that the authors of the studies ignored the drop in mercury excretion, after two years, in the urine in the children with amalgam fillings, even though the mercury exposure from amalgam remained the same or increased. This is explained in a response by Dr. Boyd Haley, to the 2006 publication, in JAMA, of the NIDCR-funded children's amalgam study. Boyd E Haley, PhD (b September 22, 1940, Greensburg Indiana) is a professor at the University of Kentucky, where he has been the chairman According to Haley, this is evidence that these children are losing the ability to excrete mercury with increased exposure.  This observation points to a strong limitation in the use of mercury concentrations within urine as an indicator of mercury exposure from amalgam (and, potentially, as an indicator of mercury concentration within the bloodstream).
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  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 around for many more years to come. 
In 1840, the American Society of Dental Surgeons was founded by a group of dentists who met in New York city. A dental restoration or dental filling is a Dental restorative material used artificially to restore the function integrity and morphology of missing tooth The American Society of Dental Surgeons (ASDS was the first national dental organization formed in the United States of America It was the only national organization of dentists in existence at the time. Chapin A. Harris, the co-founder of the ASDS and the first dental school in the US, the Baltimore College of Dental Surgery, spoke of dental amalgam in his opening address: "It is one of the most objectionable articles for filling teeth that can be employed, and yet from the wonderful virtues ascribed to this pernicious compound by those who used it, thousands were induced to try its efficacy". Chapin A Harris AM, MD, DDS (1806-1860 was an American Physician and Dentist, born May 6 1806 The Baltimore College of Dental Surgery, (founded February 1 1840, is the birthplace of the Doctor of Dental Surgery degree ( D  In 1845, the ASDS had members sign a mandatory pledge promising not to use mercury fillings because of fear of mercury poisoning in patients and dentists (at the time, dentists made amalgam by mixing liquid mercury and the other components of amalgam themselves in their office, a practice which continued until pre-filled amalgam capsules became generally available in the 1960s). Mercury poisoning (also known as mercurialism, hydrargyria, Hunter-Russell syndrome, or acrodynia when affecting children is a Disease  During the next decade some members of the society were suspended for the use of amalgam. Because of its stance against dental amalgam, membership in the American Society of Dental Surgeons declined, and due to the loss of members, the organization disbanded in 1856.
In 1859, the American Dental Association (ADA) was founded by twenty-six delegates representing various dental societies in the United States at a meeting in Niagara Falls, New York. The American Dental Association (ADA is an American Professional association established in 1859 and has more than 152000 members The ADA did not forbid use of amalgams. The ADA position on the safety of amalgam has remained consistent since its foundation. As of 2006, the ADA has over 152,000 members and is the largest and longest-standing professional association of dentists in the world.
Amalgam formulations and properties were gradually improved, notably by Dr. G.V. Black in 1895. Greene Vardiman Black (1836 - 1915 commonly known as GV Black, is known as one of the founders of modern Dentistry in the United States Despite these changes, debate over the use of amalgams persisted in the dental profession. The ADA maintained until 1984 that mercury was bound in amalgam and did not release mercury vapor. In the 1970s studies demonstrated that a small amount of mercury vapor was constantly being released from amalgam, corroborating the first such study published in 1882 in the Ohio State Journal of Dental Science by Dr. Eugene S. Talbot. 
Some legislators have introduced legislation to prohibit or restrict use of amalgam fillings. Legislation (or " Statutory law " is law which has been promulgated (or " Enacted quot by a Legislature or other Governing
Japan regulates the use of amalgam fillings.
In most European countries (for example, the United Kingdom, France, and Italy), amalgam use is unrestricted. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located This article is about the country For a topic outline on this subject see List of basic France topics. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest Some other countries, such as Sweden, have banned or regulated the use of mercury in dental amalgams, citing health or environmental concerns. "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. The Swedish Chemicals Inspectorate (KemI) maintains a web site containing a report on the investigation for a general ban on mercury on which it states, "KemI judges that there are strong grounds for banning amalgam for environmental reasons. From a health point of view there is every reason to apply a precautionary approach. " Some countries, notably Austria and Germany, have some restrictions on dental amalgam, such as permitting its use for the general population, but not for children, pregnant women, people with kidney problems, when in contact with other metals, such as braces, and in people with mercury sensitivity. Austria (Österreich ( officially the Republic of Austria (Republik Österreich Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe.
Amalgam use is illegal in Norway as of January 01, 2008. Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional New Year See also New Year The Ancient Romans began their consular year on January 1st since 153 BC 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common 
Sewers from Norwegian dental clinics older than 1994 (or if there is other reason to believe amalgam have ended up in the sewers instead of the patients mouth) shall be cleaned by experienced personnel to properly remove any residual mercury. The detailed procedure to do so is available from SFT free of charge 
In the United States, amalgams are classified as a "device," not a "substance," by the Food and Drug Administration (FDA). Under the U. S. Code of Federal Regulations, amalgams are a prosthetic device:
As a result of this classification, amalgams have not been subject to official government testing in the United States such as is required for medicines. However, the FDA maintains a web page on the use of amalgam, last updated in December 2002, on which it states, "no valid scientific evidence has shown that amalgams cause harm to patients with dental restorations, except in the rare case of allergy. " The FDA's assertion that there is no scientific evidence of health risks associated with amalgam is based on periodic reviews of scientific literature it has published in so-called "white papers". But in September 2006, a joint meeting of three FDA committees voted that the most recent FDA white paper was limited in scope, had gaps in knowledge regarding exposure limits, included contradictory evidence, did not include data from other countries, and did not provide a rationale for excluding some studies.  According to the meeting summary posted on the FDA's web site, "To the question of whether the white paper 'objectively and clearly presented the current state of knowledge about the exposure and health effects related to dental amalgam,' the panel voted 'no' by a 13-7 margin. " Prior to the joint meeting, some scientists and consumer advocates had raised questions about the fairness of this process, as planned by the FDA. 
In 2001 in a lawsuit involving California Proposition 65 and amalgams, a California Superior Court judge ruled that all dental offices with more than nine employees must provide notices on the contents of dental fillings. Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. Proposition 65 is a California law that has been in effect since 1986 to promote clean drinking water and keep toxic substances that cause Cancer and California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The mandated notice reads:
In 2002, eight members of the U.S. House of Representatives introduced the Mercury in Dental Filling Disclosure and Prohibition Act  (H. See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. The United States House of Representatives is one of the two chambers of the United States Congress; the other is the Senate. R. 4163, 107th Congress, 2nd Session, April 10th 2002), which would have prohibited any mercury in dental fillings starting in 2007. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. In an interim period between July 1, 2002 and 2007, the bill would have required labeling of amalgam with a warning. The bill was referred to a subcommittee, which tabled it. Table as a verb has two contradictory meanings one in use in the United States and the other in the remainder of the English-speaking world It has since been re-introduced as bill HR-4011 by congresswoman Diane Watson, who issued a public statement after the September 2006 decision of the FDA Review panel on dental amalgam. 
Following the meeting of the joint committees on 6-7 September 2006, when the panel of outside advisers that the FDA had asked to assess the conclusions of its report on amalgam safety rejected the FDA report in a 13-7 vote, they stated the report's conclusions were "unreasonable", given the quantity and quality of information currently available. Panelists said remaining uncertainties about the risk of so-called silver fillings demanded further research, in particular, on the effects of mercury-laden fillings on children and the fetuses of pregnant women with fillings and the release of mercury vapor on insertion and removal of mercury fillings. Michael Aschner, a professor of pediatrics and pharmacology at Vanderbilt University and a panel consultant said "There are too many things we don't know, too many things that were excluded. "   
Shortly after the decision of the joint advisory panel, the president of the International Academy of Oral Medicine and Toxicology (IAOMT) wrote to the FDA to ask for an expanded review of current science on dental mercury amalgams, a definitive date for such a hearing, and a format that will assure that the full breadth of health effects is assessed. The International Academy of Oral Medicine and Toxicology is formally chartered as a Canadian non-profit corporation representing dental medical and research professionals  In a press release the ADA wrote that it " welcomes the call by a U. S. Food and Drug Administration (FDA) panel for additional review of scientific studies on the safety of dental amalgam fillings. " and reiterated that "the overwhelming weight of scientific evidence supports the safety and efficacy of dental amalgam, and it should continue to be made available to dentists and their patients " and " dental amalgam contains elemental mercury combined with other metals such as silver, copper, tin and zinc to form a safe, stable alloy. " 
A few less controversial alternatives to mercury amalgam exist such as composite resin (or "white") fillings that have been available since the 1980s. Other alternatives include gold, porcelain, and glass ionomers. An ionomer is a Polyelectrolyte that comprises Copolymers containing both electrically neutral repeating units and a fraction of Ionized units However, amalgams are stronger, more durable, and less expensive than most of the available alternatives, though some newer composite materials have demonstrated durability on par with amalgam. Most of these materials, with the notable exception of gold, have not been used as long as amalgam, and some are known to contain other potentially hazardous compounds. This is why biocompatibility testing is recommended for all dental materials as per ADA/ANSA or ISO standards, and can be performed by specialized laboratories. Biocompatibility is related to the behavior of Biomaterials and in that it is a peculiar word because it would seem that are at least two opposing uses of the same term  Some experts also caution against a too-sudden shift towards composite resin to allow time for dentists to acquire the skills needed to properly place resin fillings since " clinical studies on the longevity of amalgam and resin composite restorations placed by dental students and dentists who are experienced in both composite resin and amalgam placement show a comparable and acceptable annual failure rate for those restorations".  Teaching of amalgam techniques to dental students is declining in some schools in favor of composite resin, and at least one school, University of Nijmegen in the Netherlands, had eliminated dental amalgam from the curriculum entirely in 2001. 
A large federal health survey, NHANES III, found that the number of amalgam fillings is significantly correlated to incidence of cancer, thyroid conditions, mental conditions, diseases of the nervous system including MS, diseases of the respiratory and genitourinary systems, and disorders of the eye, circulatory, and respiratory systems. , however correlation is not the same as causation as recognized by the United States FDA, various supreme court judges and others. For example, in 1991, the United States Food and Drug Administration concluded that “none of the data presented show a direct hazard to humans from dental amalgams. ” . Additionally, on Feb. 18, 2003, the New York Supreme Court dismissed two amalgam-related lawsuits against organized dentistry, stating the plaintiffs had “failed to show a 'cognizable cause of action'. ” The plaintiffs blamed 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. ".
Toxicologists have catalogued a large number of health effects caused by mercury poisoning, thus the range of possible symptoms is very diverse and all of them can be produced by other causes, making it difficult to draw definite conclusions. Toxicology (from the Greek words toxicos and logos) is the study of the adverse effects of Chemicals on living organisms While most dentists acknowledge that a small proportion of patients may suffer from local symptoms due to mercury sensitivity or allergy, they would not agree with alternative practitioners who suspect a broad range of local and non-local health effects in a larger proportion of people. There is no substantive evidence to suggest that nearly two centuries of amalgam use has resulted in measurable health effects in patients. A 2003 report from a group of international experts reviewing various studies on mercury concludes that:
Other, lesser findings were reported, including a cross-sectional study in which cognitive function was not related to the number or surface area of occlusal dental amalgams, a case-control study in which patients with numerous amalgam fillings exhibited higher levels of neurological symptoms than the controls, and a study of self-referred patients who believed they were suffering ill-effects from dental amalgams which found no correlation between number of dental fillings and symptomatology, but higher mean neuroticism than two comparison groups (the authors concluded that self-referred patients with health complaints attributed to dental amalgam are a heterogeneous group of patients who suffer multiple symptoms and frequently have mental disorders). Case-control is a type of Epidemiological Study design. Case-control studies are used to identify factors that may contribute to a medical condition by comparing subjects
Two recent randomized clinical trials in children showed no statistically significant differences in adverse neuropsychological or renal effects observed over the five-year period in children whose caries were restored using dental amalgam or composite materials, although one study could not rule out the possibility of a small adverse effect on IQ in children with amalgam. Dental caries is a disease that damages Tooth structures resulting in what is commonly called tooth decay or cavities which are holes in the teeth 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, a subsequent 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 fetus, and also states that "exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. " Currently, EPA has set the "safe" mercury exposure level to be at 5. 8 micrograms of mercury per one liter of blood. While mercury fillings themselves do not increase mercury levels above "safe" levels, they been shown to contribute to such increase. However, such studies were unable to find any negative neurobehavioral effects.   
Research on monkeys has shown that mercury released from dental amalgam restorations is absorbed and accumulates in various organs such as the kidney, brain, lung, liver, gastro-intestinal tract, the exocrine glands.  It was also found to have crossed the placental barrier in pregnant rats and proven to cross the gastrointestinal mucosa when amalgam particles are swallowed after amalgam insertion or after removal of old amalgam fillings. 
Various diagnostic methods exist to detect the level of mercury in the body, including blood tests, urine tests, stool tests, saliva tests, DMPS or DMSA chelation urine tests, a hair analysis and others. Chelation is the binding or complexation of a bi- or multidentate Ligand. Hair analysis is the chemical analysis of a Hair sample Hair may be considered for retrospective purposes when blood and urine are no longer expected to contain a particular Opinions differ on which of these tests, if any, is the most accurate, although mainstream scientific research tends to place the most weight on chelation urine tests or stool tests when trying to assess chronic levels, or on blood or urine tests when trying to assess recent acute exposure.
The degree of accuracy which can be expected from urine based mercury tests given the observations cited above (outlining the drop in mercury excretion levels, after two years, in children with amalgam fillings despite a constant or increased magnitude in the level of mercury exposure) indicates the possibility of clear limitations in the efficacy of urine based mercury tests as an accurate statistic for the purposes of dental studies.
Further, none of these tests can link mercury levels to dental amalgams for methodological reasons, except (a) on an Epidemiological scale; or (b) through measuring levels before and after dental work. Epidemiology is the study of factors affecting the Health and Illness of populations and serves as the foundation and Logic of interventions made in the Studies have investigated both angles and results have differed, fueling the controversy since the scientific data remains inconclusive and has not yet proven either safety or danger.
Most dentists feel that while, when placing the fillings, both patient and dentist are exposed to a small amount of mercury and mercury vapor, once the amalgam has hardened (which takes less than a minute), most of the mercury is captured in the filling. Further, being trapped in the amalgam, they contend that the mercury cannot escape into the mouth except in small amounts, which they would not deem significant except in the case of hyper-sensitive patients. Opponents and some practitioners disagree, and prefer the use of alternative fillings. Because of such concerns, according to the Consumers for Dental Choice, fully one third of the dentists in the US are currently 'mercury free'. Consumers for Dental Choice (CDC is a United States Nonprofit Advocacy and Educational group based in Washington DC, that promotes Some practitioners may also recommend that patients with amalgam fillings have them removed and replaced, particularly if the patient is experiencing the symptoms that they attribute to the use of amalgam.  These professionals recommend that unprotected amalgam removal should be avoided even in routine dental procedures to avoid exposure to mercury vapor and amalgam particulate matter. 
Organizations opposed to amalgam use, such as Consumers for Dental Choice, claim to have over 65,000 studies on file implicating amalgam fillings as the cause of a diversity of health disorders. These studies have been used in various lawsuits, and were the main contributing factor to the passage of Californian legislation concerning the issuing of warnings to patients about mercury, and to the federal bill introduced in 2002 proposing that amalgam fillings be made illegal after 2006.
Consumer Reports magazine, among others, claims that the connection between many of these diseaseas and amalgam fillings is solely revenue generating propaganda for some dentists. Consumer Reports is an American Magazine published monthly by Consumers Union. Consumer Reports advised its readers on several occasions that “if a dentist wants to remove your fillings because they contain mercury, watch your wallet. ”.
Dental amalgam has also been found to be the most common contributor to oral lichen planus and a common cause of other autoimmune conditions including mutiple sclerosis, lupus, thyroiditis and eczema. Lichen planus is an Inflammatory Disease that affects the Skin and the Oral mucosa, and presents itself in the form of Papules . One British study has shown that removal of dental amalgam has been shown to significantly alleviate oral lichen planus. .
Mercury is an environmental toxin and the World Health Organization, OSHA, and NIOSH have established specific occupational exposure limits. For the European Agency see European Agency for Safety and Health at Work, (OSHA The National Institute for Occupational Safety and Health (or NIOSH) is the United States federal agency responsible for conducting research and making recommendations Amalgam removed from teeth is classified as toxic waste in various countries. Mercury from improperly disposed of amalgam may be released into sewage water. Crematoria are to establish recovery of mercury from flue gases as soon as reasonable since mercury from amalgam is released into air during cremation of cadavers with amalgam fillings.
Environmental risks are mitigated provided that amalgams are disposed of properly. ISO has issued standards regarding the proper handling and disposal of amalgam waste, and legislation to enforce these standards is being adopted in some states. 
The Association of Metropolitan Sewerage Agencies (AMSA)studied seven major waste-water treatment plants and found that dental uses were "by far" the greatest contributors of mercury load, on average contributing 40%, over 3 times the next greatest contributor. Waste treatment refers to the activities required to ensure that Waste has the least practicable impact on the environment  The EPA recognizes mercury amalgam as a major source of the mercury in the water. The Western Lake Superior Sanitary District that dentists emit . 1 grams of mercury per day per dentist. Based on this, mercury amalgam contributes 14% of the mercury in Seattle and 12% of the mercury in San Francisco. 4% of the mercury in Lake Superior is believed to originate from amalgam. </ref> The National Association of Clean Water Agencies noted in a report that purification of mercury from waste water will impose a significant financial burden upon municipal treatment plants.  Several other groups have analyzed mercury in waste water and concluded that it is a serious problem.  Other studies have shown this to be a gross exaggeration. With respect to pollution in the United States, a study done in 1992 showed that batteries “accounted for 86 percent of discarded mercury and dental amalgam a mere 0. 56 percent”. 
Among modern dentists who are exposed to mercury amalgam and vapor on a daily basis, no evidence of mercury poisoning has been demonstrated. Some studies have indicated that mercury from amalgams affects some dentists mildly. Dentists in several large-scale studies performed multiple cognitive and behavioural tests and, compared to a normal population, lagged behind in many areas. In one study this included 14% worse scores in memory, co-ordination, motor speed and concentration.  The study did not demonstrate any link between mercury exposure and these lagging scores, however. A newer study also found a link between cognitive impairment (including mood) and dental work, even though "exposure among these dental personnel are not much greater than exposures to the general population through the dental amalgam in their fillings" as shown by urinary studies. Twelve of 13 symptoms were correlated with greater mercury exposure.
A study examining the health effects of mercury on dentists in the UK published in the Occupational and Environmental Medicine Journal concluded that 180 dentists had on average 4 times the urinary mercury excretion levels of 180 people in a control group. Dentists were significantly more likely than control subjects to have had disorders of the kidney or memory disturbance. No direct correlation between urinary mercury levels and the disability, however, was found. Urine testing is unreliable for showing lifetime mercury accumulation rather than recent exposure.