“Silver” Fillings & Ongoing Mercury Exposure – What Studies Show

In less than a year, European dentists – with very few exceptions – will no longer be allowed to fill teeth with amalgam as they join dozens of other nations in severely limiting the use of dental mercury.

“Silver” Fillings & Ongoing Mercury Exposure - What Studies Show

Despite its having been the first nation to join the global mercury reduction treaty known as the Minamata Convention, the United States is not yet among those countries.

But even if all American dentists were to stop placing “silver” mercury amalgam fillings today, there would still be millions of mouths containing millions of mercury fillings for many years to come.

Those fillings are a source of ongoing toxic exposure, as mercury is continually off-gassed from them. Mercury vapor is extremely dangerous, as it’s so easily absorbed by the body. While some of it will eventually be excreted, some may accumulate in vulnerable vital organs such as the kidneys and brain.

Mercury toxicity can lead to various health problems, including neurological and cardiovascular issues. Symptoms may include tremors, memory loss, neuromuscular effects, headaches, cognitive dysfunction, irritability, fatigue, behavioral changes, and cardiovascular complications like hypertension.

Just How Much Mercury Exposure Comes from Amalgam Fillings?

Mercury exposure from amalgam fillings in one particularly vulnerable population – pregnant women

To estimate exposure, the study’s authors started with five years of data from the National Health and Nutrition Examination Survey (NHANES), looking at the number of amalgam surfaces and the urinary mercury levels for a representative sample of pregnant women. (Each tooth has five surfaces that can be filled, so fillings are described by the number of surfaces involved.)

Over one-third of the women had at least one filling and a median daily urinary excretion that was about 2.5 times higher than that of women with no amalgams. The more surfaces, the greater the mercury exposure.

The researchers also estimated the median daily mercury vapor dose for women with amalgams. About 28% had daily doses above the least restrictive EPA safety limit. Around 36% received doses above the most restrictive California EPA safety limit.

“The observation of significant and ongoing elevated exposure to Hg vapor from amalgams among pregnant women in this study,” the authors wrote, “is particularly concerning in light of multiple studies demonstrating a significant dose-dependent relationship between maternal amalgams and the amount of Hg in fetal tissues.”

Studies in sheep and rats demonstrated a significant dose-dependent relationship between maternal amalgams and the amount of Hg [mercury] in various fetal tissues. In addition to animal studies, a number of studies were undertaken to evaluate the Hg burden in human fetuses as compared to the number of maternal amalgams during pregnancy. For example, investigators observed significant correlations between maternal amalgams during pregnancy and the amount of Hg present in various fetal tissues. Other researchers demonstrated a significant correlation between maternal amalgams and Hg in the cord blood. Still other researchers observed that maternal amalgams correlated with the concentration of Hg in amniotic fluid.

Mercury Exposure from Amalgam in the General Population

Of course, anyone with “silver” amalgam fillings is at risk of exposure, and that exposure was something the same researchers looked at in an earlier study. That one also used NHANES data and likewise showed a significant correlation between the number of amalgam surfaces and the daily amount of mercury found in urine samples. American adults with at least one amalgam surface – almost 60% of those studied – had higher mercury levels than those with no amalgams.

For 54.3% of American adults, their estimated daily mercury vapor exposure exceeded the most restrictive safety limit set by California’s Environmental Protection Agency (EPA).

“Toxic mercury vapors are continually off-gassed from dental amalgam fillings with stimulation such as chewing,” explained David Kennedy, DDS, in a news release for the International Academy of Oral Medicine & Toxicology. 

With [this] new research joining the ranks of hundreds of other studies, it is abundantly clear that mercury from amalgams pose a danger to everyone, including unborn babies, patients, dentists, and dental employees.

It’s just one more reminder why our office is proudly mercury-free AND mercury-safe, following the strictest of safety protocols to protect our patients, ourselves, and our planet – and why we support every effort to get amalgam out of American dentistry for good.