Julio Fernandez has had only four cavities, ever. For the first two, treated when he was young, his dentist used fillings that contained mercury, those silver fillings that have become less popular than the resin-based or ”white” fillings.
Over the years, Fernandez, now 46 and an international trade professional in Washington, D.C., was aware of the ongoing discussion about whether mercury fillings are safe to leave in or should be removed. Every time he got routine dental care, he asked his dentists about them.
“For years, they would look at them and always say, ‘They are fine, they are not showing any cracks. What we advise is, unless they are falling apart that you do not touch them,'” Fernandez says.
But then, last summer, when he went in for his routine checkup, his dentist said they had started to crack. The dentist advised removal of the mercury fillings and replacement with a resin-based filling.
FDA outlines groups at higher risk
Recently, the U.S. Food and Drug Administration (FDA) also weighed in on mercury fillings. In updated guidance issued last September, the FDA said that the silver fillings, also known as dental amalgam, may cause health problems for some people in high-risk groups. It recommends those who may be at higher risk use non-mercury alternatives, such as the composite resins.
The FDA says groups at higher risk for potential health effects from mercury fillings include:
Pregnant women and their developing fetuses
Women planning to get pregnant
Nursing women and their newborns and infants
Children, especially those younger than age 6 years
People with pre-existing neurological diseases, such as multiple sclerosis, Alzheimer’s or Parkinson’s disease
People with impaired kidney function
People with a known allergy to mercury or other components of dental amalgam
The FDA is not recommending that anyone remove or replace existing amalgam filling in good condition unless considered medically necessary. Doing so without medical need, the FDA says, can result in potential loss of healthy tooth structure as the filling is removed, as well as exposure to mercury vapor.
Why the new guidance? The FDA issued it after a public hearing in 2019. Some experts and members of the public at that meeting expressed concern about the cumulative effect of mercury vapor exposure not only from fillings but other sources, such as the environment.
The details of amalgam
Dental amalgam is a mixture that includes mercury, silver, tin and copper. At high levels, mercury exposure (from many sources, including environmental ones such as coal burning or mining) can have toxic effects on the nervous, digestive and immune systems as well as the lungs, kidney, skin and eyes, the World Health Organization says.
A filling made of mercury does release a small amount of mercury vapor over time, the FDA says. These low levels are generally not harmful when inhaled but some high-risk people may have issues, according to the FDA. The amount of vapor released from a filling can depend on how old it is and a person’s habits, such as grinding of teeth.
What the research says
In 2016, researchers from the University of Georgia’s College of Public Health analyzed data from nearly 15,000 people, looking at the amount of mercury in their blood and the number of fillings they had. Those with more than eight surfaces of mercury filling did have the highest level of mercury in their blood compared with those who had no fillings or fewer than eight. However, the researchers did not study whether those with more than eight fillings had more health issues.
Since the FDA guidance was issued, Cleveland Clinic weighed in, concluding the fillings are generally safe.