Skip to comments.Studies of dental fillings reassuring
Posted on 04/18/2006 7:01:06 PM PDT by neverdem
CHICAGO -- Two long-awaited, government-funded studies found no evidence that dental fillings containing mercury can cause IQ-lowering brain damage or other neurological problems in children.
Children with such fillings were no more likely than other youngsters to suffer such problems, the researchers found.
Some experts found the findings powerfully reassuring. But the studies are unlikely to end the fierce debate over the long-term effects of what are known as amalgam fillings, and some advocates bitterly accused the researchers of conducting unethical experiments on children.
Amalgam fillings, also called silver fillings, are made of mercury and other metals and have been used by dentists for more than a century. But their use has dropped in recent years as more and more doctors switch to resin composite fillings, which are considered more appealing because they are white.
Some advocacy groups and dentists have long contended that the mercury in fillings can leach into the body and cause harmful neurological effects, including autism.
The latest studies were published in Wednesday's Journal of the American Medical Association.
"We didn't see any indications of harm to these kids," said Dr. Timothy DeRouen, a University of Washington professor of biostatistics and dental public health sciences, who led a study of 507 children, ages 8 to 10, in Portugal to determine if mercury fillings had any neurological effects. "And we tested them repeatedly over seven years."
The other study, led by Dr. Sonja McKinlay of the New England Research Institutes, looked at the effect on intelligence, memory and other mental functions, and kidney function. It involved 534 children in New England, ages 6 to 10.
McKinlay said she is confident that such fillings are safe for children in this age group, in large part because the youngsters were given far more amalgam than the average American child gets.
"If there was no sign of any health problems from this study in these kids with all this amalgam in their mouths ... you know it is going to be safe for kids in the same age group in the rest of the country because they are getting much less exposure," she said.
McKinlay also said that while the study revealed children with the mercury fillings had higher mercury levels in their urine, there was no evidence they had a higher incidence of kidney damage.
Neither study examined autism. Dr. David Bellinger, an author of the New England study, said that autism so rare that it wouldn't be expected to be found among the number of children studied. Also, any children with autism would have been eliminated from the study, as would other children with prior neurological disorders.
The National Institute of Dental and Craniofacial Research funded the studies.
"From a scientific point of view, it gives us the confidence that these findings are not equivocal and the similarity suggests that the results are real," said Dushanka Kleinman, the institute's deputy director.
An American Dental Association official said the studies offer convincing confirmation of what previous studies have said. "This will give patients the reassurance they are making a safe and good choice," said Dr. Frederick Eichmiller, director of the ADA's Paffenbarger Research Center.
The authors acknowledged the limitations of the studies. For example, in the study of the New England children, the authors said the "possibility of very small adverse effects of amalgam on IQ score cannot be completely ruled out."
Others cautioned against reading too much into either study.
"It is predictable that some outside interests will expand the modest conclusions of these studies to assert that use of mercury amalgam in dentistry is risk-free," Dr. Herbert Needleman, a professor of psychiatry at the University of Pittsburgh, wrote in an accompanying editorial. "This conclusion would be unfortunate and unscientific."
He said, for example, it is not clear whether either study could measure subtle effects on IQ.
Jim Adams, a chemistry professor at Arizona State University and president of the Phoenix chapter of the Autism Society of America, said more research is needed, particularly on the effects that mercury fillings in pregnant women have on their fetuses.
Charlie Brown, counsel for Consumers for Dental Choice, an advocacy group pushing to end the use of mercury in dental fillings, said both studies ignore research that indicates mercury causes a host of physical and mental problems.
Brown blasted both studies as unethical, saying that children or their guardians were never told of the potential risks of the mercury fillings.
Authors of both studies disputed that contention, saying they disclosed what they were doing and why. And, said DeRouen, "We weren't doing anything experimental. We were giving standard dental treatment." DeRouen said a review board at the University of Washington found the allegations to be unfounded.
Pat El-Hinnawy, a spokeswoman for the federal Office for Human Research Protections, said DeRouen's study is under investigation.
An anti-amalgam group called the International Academy of Oral Medicine and Toxicology also announced it was filing ethics complaints with Harvard, the University of Washington and other institutions that took part in what it characterized "outrageous" experimentation on children.
Damn, mercury was going to be my excuse.
Mercury isn't as much a problem as is sulfidated iron.
Do you actually expect your fillings to last a couple of DECADES??? Lucky you!!! Depending on the dentist's skill and the oral hygiene habits and health of the patient, fillings RARELY last that long. Most people are lucky to get 10 years out of an amalgam or 5 years out of a resin filling before they start to get recurrent decay. As for the risk of a filling fracturing, that depends a lot on the size of the filling, as well as if the tooth has had root canal treatment done. It also depends on other factors, such as tooth grinding and eating partially popped popcorn kernels.
Amalgam fillings can easily last more than 10 years. Operator technique as well as hygiene are of greatest influence, not the filling material. Recurrent decay is not a given; cariology is an interdependent occurrence irrespective of restorative material as well.
If a tooth has had a root canal filling, it should be crowned, unless it is an anterior tooth. Unless standards of care where you are at are grossly different than the US.
OK, I'll blame that for my mental deficiencies and memory failures. I'll take what I can get!
Heavens, I've had some amalgam fillings in my mouth for more that 35 years. So far so good.
Use Xylitol regularly (in chewing gum, mints, squigle toothpaste) and you won't get recurrent decay.
There are also corrosion issues, which is why I got rid of my amalgam fillings 15 years ago. For a small cavity, a big hole has to be drilled in order to get the amalgam in. And all it does is fill the hole. So the area between the tooth material and the amalgam sometimes gaps (due to some corrosion taking place) and cavities form in the hole. The newer bonding materials work much better, since it actually binds to the tooth material. Small cavity found early, less drilling. There is a drawback however with bonding material and large fillings (such as replacing amalgams). There is a long term curing process (over a span of years) outside of the initial curing where the material shrinks and places stresses on the tooth material which it is bound to. Thus causing cracks, and necessitating crowns.
Actually, the preparation for an aamlgam filling should be no larger than the periphery of the decay, as long as the remaining tooth structure is not unsupported.
The gap you speak of is actually filled in by the process of corrosion, which is in opposition to the inability of resin fillings which are notorious for sensitivity because of shrinkage during the polymerization process which results in microleakage. The resins are designed to bond to the tooth structure... if done properly. That requires absolutely no contamination from moisture. These are done with a rubber dam, right??
There is no long term curing process. What you may be confused about is the continuous process of thermal expansion, whereby amalgam again is favored as it will expand and contract at a rate closer to that of the tooth material than reinforced resin.
The last three amalgam fillings I've had were inserted in 1962, 1963, and 1965, respectively, by DDS Thomas Hogan in STL, MO, now retired (more's the pity).
They are still intact today. I have no cracks evident in any tooth including those formerly filled, as of Wednesday last week.
Doubtless your caveat about ''other conditions'' should be expanded somewhat.
First of all I'm a patient, not a dds. The large resin fillings were done with a rubber dam. Thanks for the correction on the long term degradation of the resin fillings though, I didn't know about the differences in temperature expansion coefficients (I'm more in the engineering field). As for the polymerization that you describe, I thought that was the purpose of setting the material down in layers, and using the light curing wand. Anyhow my amalgam fillings were breaking down, had to go. Those fillings went back to the mid 1960's, so were 20 to 25 years old.
I'd still like mine out. It defies logic how mercury can be a toxic poison and then be put in the mouth.
For any element or chemical molecule, toxicity is dependent upon the dose, IIRC. This amalgam is a mixture that uses some elemental mercury.
Of all the forms of mercury, elemental mercury is the most commonly swallowed form of mercury, usually from a broken thermometer. Fortunately, elemental mercury from a thermometer is not absorbed from the stomach and will not cause any poisoning in a healthy person.
I have a number of them more than 30 years old.
It defies logic how mercury can be a toxic poison and then be put in the mouth.
Mercury is but one component, along with tin, copper, zinc which when triturated undergoes a chemical change to become the amalgam which is the filling material in your tooth.
Amalgam is not the same thing as mercury.
Sodium is an explosive metal in its elemental form, while Chlorine is a poisonous gas. As they chemically bond, they become common salt. But by your logic you would need to have it removed from your body as well; then you die.
Perhaps it is not logical to you, but it is based on sound scientific principles.
You can put it in your mouth if you want.
Exactly. I hate to take ANY medication because of the side effects. Fortunately, I haven't had side effects (that I know of) in the ones I'm taking now. Phoslo gave me too much blood calcium and I had to quit that one. Who knows what else is going on in my body because of the meds! Argghhh.
My mercury fillings lasted 40 years. Now they're all gone, thankfully. M
I was on coumadin but I still ate pretty much what I wanted since I had eaten veggies and green stuff BEFORE I went on it. It didn't seem to hurt and then I took myself off coumadin because of the dangers. I asked my heart doctor if I could since another heart doctor asked why I was on it after two years. He takes his patients off by six months or a year. Now I'm on plavix. Some trade, huh?
My mercury fillings lasted 40 years. Now they're all gone, thankfully. M
I assume you mean amalgam fillings, as mercury itself is NOT a filling material. It seems that you should be thankful that the fillings allowed you to keep your teeth that long. Without them, they would have decayed to the point where you would have a mouth filled with rotted teeth and abscesses if you did not have them extracted before such time.