Last month I briefly mentioned the studies published in the New England Journal of Medicine evaluating the safety of mercury fillings in children.

One study, conducted in Lisbon, Portugal, involved 507 children.

The conclusion of the authors of this study was that, “amalgam should remain a viable dental restorative option for children.”

The other study, conducted in the Boston area, involved 534 children. It’s findings “suggest that the health effects of amalgam restorations in children need not be the basis of treatment decisions when choosing restorative dental materials”.

The result was a lot of media coverage proclaiming the safety of mercury fillings in children.

I find it interesting and frustrating how much media this received; yet the story about a suit filed against the FDA to ban mercury fillings was totally ignored. (See comments on this suit in section above). 

As promised last month, I have reviewed the articles and would like to offer some comments:

First, let me summarize the two studies:

In the Portugal study, children eight to ten years old, having at least one cavity on a permanent tooth, were divided into two groups. One group received mercury fillings over the seven years of the study, the other group composite. At selected intervals, tests were given to assess memory, attention/concentration and nerve conduction velocities.

In the Massachusetts study, children 6-10 years old were divided into two groups – one to receive composite fillings and the other mercury fillings. They were treated and tested over five years. In this study they were testing IQ, memory, vasomotor ability, and renal function.

These studies are very disturbing.

First there is the ethical question about implanting mercury into children. I wonder if I can get a study funded to determine if it is safe to place a lead filling in a child’s mouth. I would doubt it – everyone knows lead and children do not mix well. So how is it that mercury fillings are still in use; everyone knows that mercury is unsafe.

The authors state that amalgam fillings “emit small amounts of mercury vapor”. Don’t you think it would be a good idea to determine what that amount is? Then knowing the amount they are being exposed to, one can determine how much of that amount is being excreted and thus how much is being retained.

In the studies the researchers looked at urinary excretion of mercury. This is one route of excretion. However the primary route for getting rid of mercury is in feces.

It is interesting to note that in the Portugal study over the first two years the amount of mercury being excreted in the urine of those with mercury fillings almost doubled over baseline. Naturally, there was no increase in the composite group. Over the next 5 years the urinary mercury decreased to a little more than the composite group. Why did the level of urinary mercury decrease? Given that mercury is continuously coming out of the fillings, one would have expected these levels to stay the same. The only logical explanations are: 1) mercury, which is toxic to the kidney, is affecting the kidney’s ability to function properly. 2) Many fillings were done on baby teeth and many of these teeth were lost as the children aged over the seven years of the study.

In the Massachusetts study the urinary mercury excretion was also significantly higher in the amalgam group. In their study this level remained higher during the five years of assessment. This may be due to the fact their group was younger at the start than the Portugal group and younger at the conclusion of the study, thus retaining more baby teeth with mercury in them. Nevertheless, both studies demonstrated mercury came out of the fillings and exposed these children to a known neurotoxin.

Considering some fillings were placed in the mouths of the children during the later years of the study in Portugal, it is probable that the kidneys were not able to excrete this extra load or else one would expect the urine mercury to have gone up. An additional consideration that should have been studied was the elimination of mercury via the stool. Was this impaired? Unfortunately this was not looked at.

Remember, 90% of mercury is excreted in the stool.

Testing the urine mercury only shows that when mercury is placed in the mouth, mercury comes out of the fillings and some is excreted in the urine. Not a good thing to be placing a known neurotoxin in the mouth which travels through the body. How much is being retained is the critical question.

This brings up another point, the result of the various tests give averages. However,research is showing there is a subset of the population (about 25%) that genetically is less able to excrete mercury. This is seen in autistic children. It would have been prudent, in trying to determine the safety of implanting mercury in a child’s mouth, to test for these genetically compromised children. Then look at excretion and retention of the mercury in these children versus the others and look for differences in the tests results of the various assessments being done. Possibly, in the Boston study, urinary excretion of mercury stayed higher then in the Portugal study because there were less of these genetically compromised children.

In the various testing conducted regarding IQ, memory, etc., both studies found there wasn’t a difference between the mercury group and the control group. Again we are looking at averages.

Also we are looking at a short period of time. At what point in time will symptoms occur? 

Mercury is associated with Alzheimer’s Disease. Twenty year olds do not get Alzheimer’s.Often, it takes decades until the body’s compensatory mechanisms can’t compensate.

What is going to be the long term effect of placing mercury in a child’s mouth when that mercury is continuously coming out of the filling like a slow dripping faucet? At what point is that individual going to exceed their personal threshold and get sick? Does it make sense to be testing a known neurotoxin to see if it is neurotoxic over a brief period of time? Where is the logic in this?

The history with lead is instructive. Originally it was thought that the effect of lead on children was either death or complete recovery. As time went on, various subtle, harmful effects were discovered and the amount of exposure which is considered “safe” has been continuously lowered over the past 50 years. 

A new patient came in a few weeks ago requesting that her mercury fillings be removed. She had asked her dentist a few months before about this and he said, “There is no problem with silver fillings. The mercury in them is perfectly OK.” She was satisfied with that, trusting his expertise. When she got home, she had a message to call her son’s school. It turned out there was a problem – someone broke a mercury thermometer in chemistry class. The kids were evacuated and a change of clothes had to be brought to the school, and the State was called in to clean up the spill.

One molar mercury filling has about the same amount of mercury as a thermometer! After that, the mother realized how illogical it is to keep an “open thermometer” in her mouth.

© 2006, Mark A. Breiner, DDS

The information presented is for educational purposes only. You should consult a qualified dentist or health practitioner for diagnosis and treatment.