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They Don’t Still Put Mercury in Dental Fillings, Do They?
Hardly a week goes by without an article in the paper or a feature on the evening news about human exposure to toxic mercury from the fish you eat, the air you breathe or the water you drink or play in.
But few people are aware that the primary source of mercury exposure for most people is their metal dental fillings, commonly called “silver fillings,” that are, in truth, approximately 50% elemental mercury. Silver comprises 25-35% of the filling and the balance is varying combinations of tin, copper and zinc. The average mercury-based filling contains about the same grams-weight of mercury that is found in the old-fashioned mercury thermometers that are being outlawed state-by-state.
In 1991, the World Health Organization published a monograph on inorganic mercury that identified mercury amalgam dental fillings as the primary source of mercury in the bodies of those who have amalgam fillings. Yet, almost without fail, fish is routinely identified in media stories as the primary source of mercury exposure for most people. What accounts for this disconnect between the facts and journalistic accuracy? The answer lies in the 170-year history of amalgam in America and who controls the information that gets to dental consumers and the media.
History of Mercury in Dentistry
In 1833, the Crawcour brothers, who were French dentists, immigrated to the United States and introduced the use of amalgam as a dental restoration material. The medical community was well aware of the toxicity of mercury. Nineteenth century hat makers were known to go insane from felting hats with a mercury solution. Lewis Carroll made that knowledge part of the popular lexicon with his nonsensical Mad Hatter in his best selling novel, Alice in Wonderland. Additionally, the poor quality of the amalgam also led to its condemnation by many medical dentists. In the 1840’s these medical dentists formed the American Society of Dental Surgeons (ASDS) and required its members to sign a pledge promising to not use amalgam.
However, once amalgam was introduced in America, tradesmen, primarily barbers and blacksmiths, could easily make amalgam from filings of silver coins and other metals, using liquid mercury to amalgamate the mixture of metals, creating a soft pliable plug that could be quickly and easily tamped into a hole in a tooth. The amalgam quickly hardened into a strong resistant substance that could withstand the rigors of chewing. Amalgams were sold to the common man as an inexpensive method to save teeth, and its installation was relatively painless compared to other methods of the day.
Some medical dentists saw the advantages of amalgam. It was inexpensive, easy to use and broadened the potential patient base. Ultimately, dissident medical dentists and tradesmen-dentists formed a competing dental trade organization in 1859 which is now known as the American Dental Association (ADA). The ASDS faded away and with it, the vocal concerns about mercury-based dental fillings.
The use of amalgam was founded in controversy that continues to the present. Up until 1986, the ADA and its member dentists asserted that the mercury in amalgam, when combined with its constituent metals, was inert, did not expose patients to any mercury and was not a source of health harm. However, as early as the 1860’s, medical doctors were making a link between amalgam fillings and specific health harm. A lecture by William P. Wesselhoeft, MD, Boston, MA, on his clinical experiences was written up in an 1896 edition of the International Hahnemannian Association Transactions. It included a post-lecture discussion with other doctors about their similar experiences.
The connections these doctors made between health harm and amalgams was unequivocal and included: tongue ulcers (“I firmly believe the ulcer was caused by the contact with the filling.”); chronic gastritis (“The result of the removal of the fillings was a perfect, and permanent cure of his chronic gastritis.”); tinnitus (“The tinnitus she says is now ‘so far off’ that she scarcely hears it); disfiguring eczema (“…his mother sent me this message: ‘The Lord be praised that our son is again presentable through your ministrations.’”); chronic rheumatism (“I have relieved chronic rheumatism many times after having the mercurial amalgams removed, and I think this is the experience of a great many in our profession.”); and, follicular pharyngitis (“…follicular pharyngitis, and many other affections of the throat, post-nasal catarrh, etc., are practically incurable until these amalgam fillings are removed.”).
One theme that is common for patients with mercury amalgam poisoning is the difficulty of finding a diagnosis for their wide-ranging maladies. Medical doctors are not trained to look to dental materials as a source of health problems and dental consumers have little knowledge about the composition of fillings being placed in their mouths. Patients don’t ask about them and dentists don’t volunteer the information even though the doctrine of “informed consent” requires such a discussion.
A February 2006 Zogby poll on mercury amalgam dental fillings revealed that 76% of Americans are unaware that mercury is the primary component of amalgam fillings. 92% are of the opinion that dental consumers should be informed of the available alternatives.
How have American dental consumers been kept ignorant of the existence of toxic mercury in dental fillings for over 170 years? Several factors play a role. While it isn’t clear if the ADA coined the phrase “silver fillings,” it is clear that the term is the descriptor of choice by the ADA and most dentists. The ADA’s website and its brochures, which are sold to dentists for distribution to patients, consistently refer to these fillings as “silver fillings” or as “dental amalgam,” but never as “mercury fillings.” Consumers in states like California and Maine, which have passed laws requiring dentists to provide patients with documents disclosing the mercury content of amalgam, have spent years wrangling with the dental boards and dental associations for honest documents. Arizona and New Hampshire have passed such laws, but have failed to enforce them to date.
The ADA has taken affirmative steps to prevent dentists from informing their patients about the existence of or the risks of mercury in dental fillings. The ADA, in 1990, adopted an Ethical Rule (5A), which prohibits dentists from removing amalgam, “for the alleged purpose of removing toxic substances from the body when, performed solely at the recommendation or suggestion of the dentist … [because it] is improper and unethical.” A number of state dental boards have adopted these ethics rules. The effect has been to intimidate dentists from talking at all about amalgams for fear that any statement critical of the dental material might imply a recommendation for removal.
The Oregon Board of Dentistry has not adopted the ADA’s ethical rules, but it did adopt a written policy on amalgam that was even more punitive. Oregon law provides that a dentist can be disciplined, including loss of license, for commission of a fraud against a dental consumer. The amalgam policy deemed it a fraud for a dentist to recommend the removal of an amalgam for the purpose of removing a toxin. Actions by the Oregon ACLU resulted in the rescission of this policy in March 2003.
The most effective tool of state dental boards to keep dentists from warning patients about the dangers of mercury amalgams is the disciplinary process that has been used against mercury-free dentists with the encouragement and support of the ADA. Mercury-free dentists have been disciplined, and even lost their licenses to practice, for practicing mercury-free dentistry, for advertising their mercury-free practices, for publishing articles or lecturing about mercury-free dentistry. These actions by state boards have had the effect of imposing a “gag order” on mercury-free dentists, preventing them from performing their fiduciary duty to inform their patients of the risks of treatments and the alternatives available.
The Oregon Board of Dentistry investigated four mercury-free dentists in 2005 for producing an “infomercial” on mercury-free dentistry that aired multiple times on a Portland Metro area network station, but, after receiving a lengthy, detailed response, dismissed the matter. And, in 2006, the Board investigated one of those same dentists for advertising his practice in Portland Monthly magazine; a matter that is still pending. These actions by the Board are effective at keeping other mercury-free dentists from speaking out for the fear of bearing the costs to defend the investigations and the risk of losing their right to practice their profession.
In response to pressure from the ADA, Dentsply revised this product warning document, explaining that the wording was necessary to comply with German labeling requirements and the purpose of the revision deleting the warning was to assure that the “contraindications and warnings are consistent with accepted scientific information,” i.e. German citizens are entitled to warnings but Americans are not. This is yet another way the ADA assures that Americans do not know about the risks of mercury in dental fillings.
There is a very real risk to mercury-using dentists if they keep following the ADA’s “code of silence” about the mercury content of amalgams and health risks associated with them. David Barnes, a dentist in Tennessee, sued Kerr Manufacturing, an amalgam manufacturer, for mercury poisoning from use of Kerr amalgams in his practice. In 2005, the federal Sixth Circuit Court of Appeals, affirming the trial court’s dismissal of the case, found that the product warning sufficiently notified Barnes that mixed dental amalgam was dangerous.
The Court noted, “the label on each jar of dental amalgam capsules featured not only a skull and crossbones next to the word ‘Poison,’” but also a list of illnesses, including “bronchiolitis, pneumonitis, pulmonary edema [and] redness and irritation to [the] eyes and skin.” Likewise, the Court noted, the MSDS (material safety data sheet, provided to all dentist-buyers) warned that chronic mercury exposure could lead to “nervous irritability, weakness, tremors, gingivitis, erythrism and graying of the lens of the eye.” Further, the Court ruled that the other ingredients mixed in amalgam with the mercury silver, copper and tin are not claimed by the manufacturer to “neutralize the danger while the dentist is working with the product.”
Dr. Barnes admitted that he was aware of mercury’s toxicity, but testified that in dental school, he was taught that mixed dental amalgam was safe and the mercury rendered inert by mixing it with other metals. That evidence carried no weight with the court. This fact alone should give all dentists pause. Not only because they have no recourse if they are harmed by their exposure to mercury, but because those same warnings that protected Kerr are not given to dental consumers.
Under the “learned intermediary” doctrine, the manufacturer could also be insulated from liability cases brought by dental consumers. That doctrine is based on the assumption that a medical/dental professional, in fulfillment of his fiduciary duty to his patient, will pass along manufacturers’ warnings and any other information a patient would want to know about treatments and their risks before giving consent for treatment. In defense of a lawsuit, the manufacturer would assert that its duty is complete upon warning the dentists; the warnings to patients must come from the “learned intermediary” the dentist. Furthermore, the Court’s opinion provides a direct challenge to the ADA’s proclamations of amalgam safety. By implication, the court found that amalgam carries a health risk and warnings were required, and then it found that the warnings were adequate.
Thus, dentists are placed in a classic Catch-22: if the dentist fails to warn patients of the risks of mercury in amalgam, he faces potential liability for health harm; and, if the dentist gives such warnings, she faces risk of discipline by the state dental board, including possible loss of her professional license to practice.
Sandra Duffy, J.D. is Board President of Consumers for Dental Choice. She lives in Lake Oswego, Oregon, and may be contacted at email@example.com.
2 WHO, Criteria #118, p.36 (1991).
4 Clarkson, Thomas W., Element of Mystery, Environmental Health Perspectives. (EHP) Vol 110. Suppl 1. pp 11-23. 2002. (Dentists maintain that mercury in "amalgam becomes inert once the fillings have been allowed to set for several days, and that long-term danger to the patient from [mercury] vapor is therefore remote.”)
7 See for example: Answers to your questions about Silver Fillings, A Safe, Affordable Option in Tooth Restoration, ADA, Chicago IL, 2000.
10 Answers to your questions about Silver Fillings, A Safe, Affordable Option in Tooth Restoration, ADA, Chicago, IL, 2000. The factual information in this patient brochure, used to calm concerns of dental consumers about the use of mercury in dental fillings, is contained in a scientific rebuttal prepared by the International Academy of Oral Medicine and Toxicology, a mercury-free dental association. See, http://emporium.turnpike.net/P/PDHA/mercury/asr.htm
Site updated Fall 09