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Anti-amalgamists often assert that the American Dental Association (ADA) does not state that amalgam restorations are unsafe because of the threat of lawsuits from patients who have claimed injuries from mercury-containing amalgam restorations [1,2]. The ADA was named in a malpractice lawsuit in 1992 in California by a patient who also named Johnson and Johnson (the manufacturer of the amalgam) and the dentist who removed the patient's amalgam restorations (Tolhurst vs Johnson & Johnson Consumer Products, Inc).  The patient allegedly developed flu-like symptoms and inflammation of his peripheral nerves after an occlusal adjustment of his amalgam restorations. The dentist diagnosed the patient's symptoms as related to mercury toxicity and removed the patient's amalgams, exposing the patient to more mercury. The plaintiff alleged that the ADA's statements that dental amalgam was safe and effective amounted to negligent misrepresentation.
The judge dismissed the ADA from the lawsuit (leaving the other defendants), mostly on free speech grounds. As a membership organization, it represents member dentists, not individual patients. The ADA has stated that specific treatment decisions should be up to the individual practitioner. In other words, regardless of whether the ADA states that amalgam is safe or unsafe, the ADA is not legally liable for any alleged harm from amalgam restorations.
According to those who oppose the use of amalgam, the ADA states that mercury-containing amalgams are safe  because the ADA fears lawsuits. But the ADA was included in the lawsuit specifically on the grounds that the ADA has stated amalgam is safe. Had the ADA stated that amalgam was unsafe, it would not have been named in this lawsuit. If the ADA really were so concerned about lawsuits (as opposed to the safety and effectiveness of dental materials), perhaps it would have stated that amalgam is unsafe.
An internet search  revealed that of 67 patents held by the American Dental Association Health Foundation, the non-profit research arm of the American Dental Association, only two were for amalgam formulations (US04078921 & US04018600). The American Dental Association itself has never had a patent on any amalgam formulations. Both of these patents have expired; neither was ever licensed. In other words, neither the ADA nor the ADA Health Foundation has ever received any royalty from any amalgam ever placed. The ADA Health Foundation has not pursued any research activity related to amalgam or its use for more than 15 years. (Eichmiller F, personal communication, February 3, 2000). There is not merely one patent for amalgam; instead there are many different patents for different formulations and applications of amalgams, most of which are owned by the manufacturers, which do receive royalties for their patents.
If there is an incentive for the ADA to "promote" a particular type of restorative material, then it must be resin composite. The ADA (along with the National Bureau of Standards and National Institute of Dental Research) actually funded the invention of composite restorative materials in the 1950s [6,7]. The American Dental Association Health Foundation holds at least 15 patents related to resin composite. Two of these recently expired, but 12 are still active. Most or all of these are licensed, meaning the nonprofit ADA Health Foundation receives a royalty when its patents are used. The American Dental Association has stated that amalgam is safe and effective despite the fact that its research foundation receives financial remuneration for alternative filling materials and no remuneration for amalgam restorative materials. Furthermore, the ADA continues to support more than US $1 million in research each year through the ADA Health Foundation for the development of nonamalgam technologies. Although the ADA does not "promote" any dental material, it has stated that both amalgam  and composite restorations are safe and effective.
Dr. Wahl practices dentistry in Wilmington, Delaware. This article was originally published in Quintessence International 32:525-535, 2001 and is reproduced here with the kind permission of Quintessence Publishing Co. The author also thanks Drs. J. Rodway Mackert, Ivar A. Mjör, and Fred Eichmiller for reading the manuscript and offering several helpful suggestions.