A Perennial Controversy

In February of this year, the California Dental Association issued a document titled "Major Issues Facing Dentistry in 2001." Eleven concerns made that heralded watch list. Monitoring of managed care, dental student debt relief, licensure by credential, and a Denti-Cal fee increase were among the high-visibility issues.

It could be said that our current candidate for inclusion on that list, dental amalgam, was suspiciously absent because of the early time of the year that this list was prepared. It could also be that this issue has been one of those continuing little irritations to the dental profession that has not yet been the beneficiary of a strong scientific study that conclusively ends speculation about its safety. Or, looked at from a different perspective, the dental profession has yet to benefit from a study that shows an alternative material that offers the same cost benefits and satisfactory long-term restorative durability as amalgam and couples these qualities with unquestioned safety.

Yes, dental amalgam is back in the spotlight. However, it never really slipped completely off the radar screen since the last major challenge to its efficacy during the unforgettable "60 Minutes" episode of late 1990. It has been an issue for more than a century; and, as a result, it may not make any Top 10 list unless there is a major event to trigger it, such as the one a decade ago.

However, amalgam has continued to be a frequent topic of controversy for a combination of reasons. First, there has been the matter of Proposition 65 citations that have referred to amalgam and other dental treatment materials as having "chemicals" that can cause cancer, birth defects, or other reproductive harm. Then there is the matter of mercury in wastewater in San Francisco Bay and other less well-known locations in the California environment. Estimates (not verified as accurate) by publicly owned treatment works in San Francisco and Seattle suggest that the dental office contribution to the amount of mercury in wastewater treated in their plants is between 6 and 14 percent. Finally, there is organized, ongoing activity by groups such as the Americans Against Mercury coalition that keep the suspicions about negative health effects caused by mercury and mercury vapor foremost in the minds of the media and the public.

At the time of this writing, we believe that two of the above reasons have recently brought the questions surrounding dental amalgam back into focus. If concerns involving amalgam continue to surface, as they have recently, it should become one of the problems to make the end-of-the-year list of major issues of 2001. It is unfortunate that dentistry is continually faced with a recurring public relations dilemma because of the unsubstantiated concerns about the effects on the health of the public of the mercury in this restorative.

The first activity to focus on amalgam this year was the Proposition 65 enforcement, which has been citing dentists with practices of 10 or more employees for not posting a warning about the potential harmful effects on health by mercury in amalgam. In late April, Americans Against Mercury announced legal actions against individual dentists and dental manufacturers, among others, in a first round of class action lawsuits and other measures seeking "the outright and immediate ban of the use of mercury in the U.S." according to a report in the ADA News. The initial suit, which was filed in Maryland by five dentists and seven patients, was featured in a Wall Street Journal article on May 10, positioning it as a problem with national significance. According to the WSJ, the plaintiffs argued that regulators such as dental boards "use ‘control of dental licenses to punish or threaten punishment of dentists who criticize mercury amalgam,’ an action that violates the dentists’ First Amendment rights."

While not confirmed, the ADA News believed at press time that the ADA was named as a defendant in one of these lawsuits, brought by an individual against her dentist for alleged malpractice. The WSJ article explores some of the history of the "Amalgam Wars," as it puts it, and presents a report of a patient who allegedly developed mercury poisoning from a new filling containing mercury. It also offers comments from a chemist who published several studies using rat and human brain samples showing that brain tissue exposed to mercury develops the same biochemical defects seen in Alzheimer’s disease. It goes on to print a response attributed to the American Dental Association regarding mercury from amalgam restoration as a factor in the development of Alzheimer’s disease: "The ADA responds by pointing to a study published in its journal that concluded that mercury in fillings ‘does not appear’ to be a factor in the development of Alzheimer’s disease."

In a further attack on the credibility of the ADA study, the article goes on to claim that one of the study’s authors "is wary of that conclusion."

The same chemist is quoted in ADA News as being critical of a lack of National Institutes of Health funding for studies that look at the "potential neurotoxicity of mercury routinely placed into human contact by medicine and dentistry."

On a positive note, the ADA News report stated that the National Institute of Dental and Craniofacial Research is supporting two large clinical trials on the health effects of dental amalgam. Unfortunately, this information is not included in the WSJ report. The ADA NEWS also mentions other ongoing studies and reported that the chair of the House Committee on Government Reform on April 25 called for a study on the safety of low-level medical and dental uses of mercury, including amalgam, by the National Institutes of Health.

Both ADA Online and CDA Online are replete with position statements reviewing the scientific literature on amalgam, which collectively seem to conclude that amalgam continues to be a safe and effective restorative material. Nonetheless, it seems that the problem facing the profession is that the science included in these position statements is not convincing to the media in view of the barrage of criticism and the unsupported "scientific" claims of the organized anti-amalgam forces. Statements such as the recent one attributed to ADA by the WSJ, "the mercury in amalgam does not appear to be a factor in Alzheimer’s disease," are positive in supporting continued use of amalgam, yet seem to lack the killer instinct that might successfully quiet the critics.

Similar statements include:

* The 1991 Food and Drug Administration panel statement that found "no valid data to demonstrate clinical harm to patients from amalgams or that having them removed would prevent adverse health effects or reverse the course of existing diseases";

* The 1993 U.S. Public Health Service report that stated "there is no health reason not to use amalgam, except in the extremely rare case of the patient who is allergic to a component of amalgam," and;

* The 1997 FDI World Dental Federation and World Health Organization consensus statement on dental amalgam, "No controlled studies have been published demonstrating systemic adverse effects from amalgam restorations."

Unfortunately, the statements seem defensive and leave open the possibility that a controlled study might be brought forward that demonstrates some adverse systemic effects from the mercury in amalgam. Critics inside and outside of dentistry continue to feed the suggestion that the ADA, or research supported by the organized profession, is hiding something negative about the health effects of amalgam. Perhaps the current NIDCR clinical trials or other ongoing studies will be able to deliver a conclusive finding in this controversy. Such a finding would have been a welcome solution during most of the past decade.

The other solution to this dilemma would be the development of a substitute material that is as cost-effective, easy to manipulate, and durable as amalgam that could be shown to be safe. With each passing day, the likelihood that such a miracle material can be developed fades just a bit. Our optimism took a major hit when composite resin showed up at the head of the Proposition 65 list of materials (alongside amalgam) used in dental treatment that "contain chemicals known to the state of California to cause cancer, birth defects, or other reproductive harm."

Dentistry and dental research may succeed in finding more nearly perfect materials to restore the damaged dentition, but in the consumer-oriented world of today, even the best and safest new materials will unlikely be able to outrun the controversy that is created by well-intended but misguided public initiatives such as Proposition 65 or interest groups that either ignore or question science in advancing their narrow objectives. CDA leadership has received reports that there are rumblings of a growing bias in California in consumer-affairs and legislative circles against the continuing use of dental amalgam (mercury) in dentistry. By the time our remarks are disseminated, we anticipate that significant new events in this controversy may have arisen.

Whether amalgam remains or can or will be replaced by a "safe" new material with similar characteristics, we live in a world of controversy that tends to be influenced more by anecdotal reports and perceived vulnerabilities about dental restorative materials than on available science. It is regrettable that in recent decades, science has not been able to provide dentistry new and more conclusive evidence about our available restoratives more rapidly. As a result, the profession individually and collectively may be placed in the unenviable position of defending its credibility in all questions concerning the continued use of a significant number of essential dental restoratives that have been classified as potentially harmful to the health of the patients we are entrusted to treat.