The Case For Zero Mercury
Amalgum Fillings
By Martin Mittelstaedt
The Globe and Mail
Mercury is a potent nerve poison, and our mouths are full of the stuff in the form of amalgam, the silver-grey material that for more than 150 years has been the material of choice to patch cavities in teeth.
For seven years, Jim Copeman says, he experienced such debilitating bouts of chronic fatigue and depression that he thought he was losing his mind.
He consulted specialists, tried therapy and took antidepressants, but nothing seemed to help until he followed a suggestion by his sister, whose similar symptoms vanished after she had her dental fillings removed.
Mr. Copeman was skeptical at first, but he had a mouthful of fillings -- 14 large ones in all -- and thought he had nothing to lose. He had them taken out earlier this year. Since then, he says, he's been transformed.
"Honest to God, it is the difference between black and white," he said. "I've started to get busy. I got my life back. I'm a normal person."
Experiences such as his are rekindling the long-running controversy over the possible health effects of filling teeth with amalgam, the silver-grey material that for more than 150 years has been the material of choice to patch cavities in teeth.
Amalgam means mixture, and the fillings, found in the heads of most North American adults, are half mercury, along with tin, copper and silver.
It's easy to see why dentists in the last century became fond of using amalgam. It's easy to work with, durable and inexpensive. When it first came into use, it was a major factor in making dental care widely available because it cost less than gold.
There was little concern about mercury because it was assumed to be inert in the filling and not to enter the body.
But research conducted in the past 15 years, much of it in Canada by investigators at the University of Calgary, has shown that trace amounts of mercury vapour are continually released from fillings, and that higher amounts are emitted every time people eat, brush or grind their teeth.
The mercury is inhaled and accumulates throughout the body, with the largest amounts in the kidneys, brain, lungs, liver and digestive tract. In pregnant women, mercury crosses the placenta and enters the fetus.
Since this early research, a growing body of further scientific evidence has raised warning flags about amalgam fillings' possible effects on patients -- and on dentists.
Mercury is one of the most poisonous materials known. It is a potent nerve poison and is one of the substances under investigation as an endocrine disrupter, a substance that interferes with the normal functioning of the hormone systems of living things.
It has been banned or removed from most of its once-common uses in paints, thermometers, batteries and other products. Dozens of advisories warn anglers against eating fish that contain trace amounts of it.
But in Canada and almost everywhere else in the world, large amounts of mercury are still placed directly in people's mouths, where the metal is uniquely positioned to enter people's bodies.
Estimates by Health Canada indicate that about half the public's exposure to mercury comes from dental amalgam.
The amounts involved are small -- in the range of a few millionths of a gram a day -- and controversy is raging over whether such exposure is dangerous.
Federal health officials studied amalgam safety two years ago and issued a statement saying that "current evidence does not indicate that dental amalgam is causing illness in the general population."
Nonetheless, Health Canada said that as a general principle "it is advisable to reduce human exposure to heavy metals in our environment, even if there is no clinical evidence of adverse health effects," provided that the costs aren't too high and alternatives are safe.
In line with this principle, the government currently recommends that amalgam not be used in children, pregnant women, people with kidney disease or the estimated 2 per cent to 3 per cent of the population with an allergy to mercury.
The Canadian position is similar to one Germany adopted in 1995. Sweden has gone a step further. It recommended that amalgam use be stopped in those under 20 in 1995. Next year, Sweden's national dental plan will no longer pay for amalgam fillings, a step toward a total phaseout.
Some dentists say Health Canada isn't being tough enough and have amalgam-free practices. They advise their patients against using it.
"I haven't used mercury since the first tests showed that mercury comes out of the fillings," said Murray Vimy, a Calgary dentist and professor at the University of Calgary who has conducted extensive testing on mercury emissions from amalgam.
Dr. Vimy said that even the tiny amount of mercury that escapes from fillings should be of concern. "They're not small [quantities]. These are pharmacological doses. Your hormones in your body run on doses that are a thousand times smaller than this."
He recommends a "zero-mercury exposure or as close to zero as possible" and is surprised that the dental profession hasn't taken an aggressive stand against its use.
"If you ask a chemist, 'Tell me about mercury' -- not a dentist now, someone who is unrelated to dentistry -- they'll tell you that mercury is one of the most toxic elements in the periodic table. They've banned mercury thermometers in hospitals all over the world. People have more mercury in one filling than you have in a thermometer."
But determining whether mercury vapour in the mouth has a deleterious effect is difficult: Few studies have looked at the medical ailments of amalgam bearers compared with people without amalgam.
The effects of mercury-vapour toxicity are so wide-ranging as to confound even the most diligent investigator. Low levels can cause tremors, loss of memory, insomnia, depression, irritability, personality changes, weight loss and distress.
The range of mental symptoms helped coin the phrase "mad as a hatter," because hat makers were once exposed to high levels of mercury.
Under Canada's regulatory system, amalgam has been exempt from a requirement that all new medical devices put into the body for more than 30 days undergo a safety review before they are marketed. When the requirement was introduced in 1982, amalgam and most other dental materials were given an exemption because they were already in use.
For those worried about amalgam, most dentists and Health Canada advise against the wholesale removal and replacement of serviceable fillings.
Even amalgam critic Dr. Vimy replaces his patients' amalgam fillings with non-metallic replacements only as they succumb to normal wear and tear.
The Canadian Dental Association also recommends against the wholesale removal of fillings, saying it doesn't make sense from a health or financial point of view, except for those with sensitivity to amalgam.
Having fillings removed and replaced can be costly. Mr. Copeman, for instance, said his cost $2,200.
There are a number of non-metallic alternatives to amalgam, including composites, resins, and ceramic crowns.
But these tend to be more costly and may not be completely risk free. Some research has indicated they can emit toxic substances while they are setting, and their safety has not been studied in much more depth than amalgam.
"We don't know quite what leaches out of these products," said Richard Sandilands, president of the association. "It's the devil you know versus the devil you don't know in some respects."
Dr. Sandilands says amalgam has proved itself. "Until we see something better, we're not going to jump off the diving board here."
Health Canada says the alternatives typically do not release toxics indefinitly, as amalgam does mercury vapour. Once cured, they tend to be inert. The department concluded that the "alternative materials now in use appear to pose lower risks than amalgam."
Dental amalgam is the subject of a class-action lawsuit sponsored by Canadians for Mercury Relief against the federal government and suppliers of the material, Johnson & Johnson Inc. and Dentslpy Canada Ltd.
Another question about amalgam is whether its use may accentuate symptoms of nerve diseases such as Parkinson's, Alzheimer's and multiple sclerosis. Health Canada, however, says no evidence has been found linking these diseases with amalgam.
Dr. Vimy says patients should try to minimize their risks, particularly in cases where other family members have these diseases. "My recommendation would be if you have a family history of neurological diseases . . . you wouldn't want to have a neurological poison diffusing out of your teeth."