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Filling you in on amalgam.

One of the more troublesome medical controversies that flare up on occasion concerns the safety of amalgam fillings used in dentistry. Some dentists-a small but vocal minority-assert that there is a clear and present danger in mercury, which comprises about 50% of each filling (the other half consisting of silver and other metals). The mercury allows the amalgam to flow smoothly into the dental cavity, adhere to it tightly, and harden to a consistency that resists abrasion.

Anti-amalgam proponents claim that many diseases-including multiple sclerosis-are caused or exacerbated by the mercury, and that replacement of the amalgam by other materials may lead to remission or cure. The Medical Advisory Board of the Society, after reviewing the subject, has concluded that there is absolutely no evidence that mercury amalgam fillings have any connection with MS or that their replacement would help patients with the disease. This conclusion is affirmed in Therapeutic Claims in MS, 1988 (Demos Publications).

And early this spring the Food and Drug Administration's Dental Devices Panel convened to review animal research and human case reports dealing with the possible hazards of amalgam fillings. The panel concluded that none of the data showed a hazard to humans, but it agreed that the studies raised questions that warrant further research. A special working group was established to identify the kinds of studies needed. The FDA said it does not advocate removal of amalgam fillings.

But the anti-amalgam proponents-lay people and some dentists-continue their campaign. They allege the mercury in the fillings contributes not only to MS but to Parkinson's disease, manic-depressive disorders, schizophrenia, and a variety of immune system diseases. These individuals insist that people with any suggestive symptoms should have their fillings replaced with porcelain, composite resins or gold-all much more expensive than amalgam. And there are dentists prepared to do the job. Most of the dental community is against removal, pointing out that amalgam fillings have been used safely for ccnturies and that replacing them for "medical" reasons would be unethical. The American Dental Association (ADA), the largest and oldest organization of dentists, said last December, "There has been considerable scientific study of amalgam and no documented evidence to support the contention that amalgam, or the mercury contained in amalgam, has any deleterious effect on the health or physical wellbeing of the millions of patients served throughout the world."

Late last year things came to a head when CBS's "60 minutes" aired a December 16 segment dealing with the controversy which seemed to be heavily biased in favor of amalgam removal. Correspondent Morley Safer opened the program by asking, "Is there poison in your mouth? The American Dental Association says there isn't, but some members say there is and have stopped using it."

Safer went on to claim that the mercury in the fillings is "more poisonous than lead or even arsenic," and listed Alzheimer's disease, arthritis, colitis, kidney and brain damage, birth defects, and symptoms of multiple sclerosis as conditions purportedly linked to mercury poisoning. He did acknowledge that no specific disease has been tied directly to the mercury in the fillings. Then he introduced four patients with chronic diseases - one with MS - who had experienced "miraculous" recoveries by having their amalgam fillings replaced with other materials.

Telephone switchboards around the country buzzed with calls from MS patients to their dentists, demanding more information about amalgam fillings. The Society itself was flooded with calls from people who were led by the show to believe that their condition could be improved by a dental process that was simple and speedy-though very expensive.

Part of the recent interest in this controversy stemmed from a scientific paper on the experimental use of amalgam fillings in the teeth of sheep. In the study, dental researchers at the University of Calgary in Alberta, Canada placed 12 amalgam fillings in the mouths of each of six ewes. Calgary researcher Murray Vimy reported that mercury from the fillings traveled throughout the sheeps' bodies, and in pregnant sheep into the fetuses; moreover, he said, within two months all the sheep experienced a loss of kidney function 16% to 80%), whereas animals that had been given chemically inert fillings showed no change in kidney function. ADA spokesman R. Heber Simmons Jr., a pediatric dentist from Jackson, Miss., was given some time on "60 Minutes" to discuss the Calgary study. At the time the results were published, he said, the AMA convened a board of experts in kidney function, a statistician, two toxicologists-and a veterinarian. All found serious flaws in the work.

Dr. Simmons pointed out that sheep are poor animals to use for such a study. They are ruminants, which regurgitate food and acid from their stomachs and chew on the cud for up to eight hours a day. No one had checked the mercury content of their food-an important factor, since most mercury in tissues comes from dietary sources. Even the kidney function measurement was faulty, according to ADA president Eugene J. Truono; he noted that if kidney function had been cut by 50%, then blood urea should have been elevated, not decreased, as the authors reported. An analysis of the "60 Minutes" segment by Accuracy in Media Inc., a Washington-based news media watchdog organization, revealed that the program had been heavily in favor of anti-amalgam proponents, with seven persons speaking against the use of amalgam fillings and one ADA spokesman, Dr. Simmons, speaking in behalf of their safety.

Concerned with the effect that such unbalanced reporting has on viewers with multiple sclerosis, Society Vice President, Research and Medical Programs, Stephen Reingold sent a letter to CBS expressing the Society's dissatisfaction with the program's "slanted perspective on this controversial subject." (The letter was copied to all Society chapters on December 19.) Better balance could have been achieved, wrote Dr. Reingold, if the program had included interviews with a Society representative, a neurologist experienced in managing people with MS, and one or more people with MS who derived no benefit from removal of amalgam fillings. (Such persons are not difficult to find.) Other telling points were made:

* MS is characterized by spontaneous relapses and remissions that may last for several months or years.

A Placebo effect" emerges when a patient is searching for a remedy and finds solace in any therapeutic modality promising benefit.

Dental professionals who use amalgam all the time have no greater incidence of MS than the general population does.

* Tens of millions of people with amalgam fillings do not have MS, and by the same token some people with MS do not have amalgam fillings.

Dr. Reingold finally said, "While we favor careful exploration of controversial issues such as [these], we consider it your obligation as well as ours to present the complete story so that those with MS can be armed with the facts when they hear about any therapeutic claim." CBS officials to this day maintain that the Safer report was a fair and accurate presentation.

What is this mercury in amalgam fillings, and how dangerous is it to people? It is elemental or inorganic mercury (as opposed to organic, which is found in paints, fungicides, seeds, foods, medicines and cosmetics), and it is used for thermometers, blood pressure devices, and dental amalgams.

Mercury toxicity is usually linked to industrial exposure, due to inhalation of mercury vapor, which may cause inflammation of large and small airways and can lead to interstitial pneumonitis, a respiratory disorder.

When exposed to high mercury levels for long periods, employees in thermometer factories have suffered tremors, confusion, vision and speech problems, and inflamed gums. These symptoms, even though they are of nervous system origin, are not indicators of MS.

When mercury vapor is taken up rapidly into the central nervous system it produces tremor and increased excitability, as was seen in the felt hat industry in the 19th century. Civil War army hats were manufactured with mercury in Danbury, Connecticut; hatmakers developed tremors that came to be known as the "Danbury shakes." In Britain hatmakers afflicted with similar tremors accompanied by emotional instability were the inspiration for Lewis Carroll's Mad Hatter.

Mercury toxicity in the home is rare.

Even when mercury is accidentally released into the bloodstream by breakage of a rectal thermometer, for example, there are no reported adverse effects.

But it is the inhalation of mercury vapor released by chewing that has the anti-amaigam proponents exercised. They cite autopsy data showing that mercury levels in the brain are about twice as high in people who have had amalgam fillings for many years as in people with no fillings. This may sound alarming, but consider:

The Occupational Safety and Health Administration (OSHA) has set guidelines for the maximum safe occupational dose of mercury at 300 to 500 micrograms per day. It is estimated that people with moderate to large numbers of fillings are exposed through chewing to barely I to 3 micrograms of mercury vapor daily, or 1% of the dose considered borderline dangerous.

No harmful effects have been reported on patients or dentists since 600 A.D., when tin-mercury dental fillings were first used in China. There have been some objections to the use of amalgam; for instance, in 1926 a German chemist named A. Slock published several critical articles. This led to the establishment of an investigative commission which in 1930 gave a clean bill to amalgams, supporting their safety and recommending their use.

The average person not working near mercury gets more exposure to the element from tainted air, certain kinds of fish (tuna and swordfish), and water. OSHA officials say- that people are exposed to about 30 micrograms a day; 10 from the atmosphere, 10 from food, and 10 from other sources. Antiamalgam proponents say that people with amalgam fillings are exposed to another 10 micrograms each day; the ADA, however, states the levels are probably 1.5 micrograms per day.

If mercury from amalgam fillings caused any disease, chances are that dentists and dental assistants who work with amalgam every day would be affected. An ADA survey of 1,000 dentists showed no correlation between measure of kidney function and urine mercury concentrations, which were used as indicators of mercury exposure.

"Dentists receive far more mercury exposure than patients, and place hundreds of thousands of amalgams annually," observes ADA president Eugene Truono. "If there were a problem with mercury exposure you would expect it to Show up in dentists, and yet dentists do not suffer from any adverse health effects as a result."

The only documented health effect of amalgam over the years is mercury allergy, which affects fewer than one in a million people. They develop either local or general skin reactions which usually subside within two or three weeks.

Anti-amalgam dentists use a variety of screening mechanisms to determine mercury levels, including a symptom questionnaire, an electrical corrosion reader, skin patch test, and mercury level analyses. In the journal Operative Dentistry, Vol. 13, 1988, Woodhaven, N.Y. dentist John E. Dodes questioned the scientific methodology of all these mechanisms.

He concluded, "The review of the literature on amalgam fillings and mercury establishes the safety and continued usefulness of silver-amalgam fillings. In critically evaluating some of the theories, diagnostic tests, and treatments promoted by the anti-amalgam fringe, I have found a lack of any valid, scientifically sound data to support the contention that amalgam is dangerous, much less that it causes serious disease."

In emphatic agreement is Dr. Alvin Jacobs, a New York dentist who has been using amalgam fillings for 34 years. He says he has never seen one case of mercury illness or allergy caused by the fillings.

"Some of my patients asked about having amalgams removed after the '60 minutes' program," he told INSIDE MS. But I told them it was not advisable. Not only would it be useless but they might risk damaging healthy tooth structure or injuring a nerve in the process. I also tell my patients I have amalgam fillings in my own mouth, some of them recent replacements of originals. I have complete faith in them."

- Phyllis Shaw

Science Editor
COPYRIGHT 1991 National Multiple Sclerosis Society
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:mercury content in dental fillings
Author:Shaw, Phyllis
Publication:Inside MS
Date:Jun 22, 1991
Words:2009
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