Mercury Dental Amalgam Fillings Health Risks: Why FDA Says the Drill Is the Riskiest Moment
A silver filling may give off the most mercury vapor at two moments: when it goes in and when it comes out. FDA’s announcement on high-risk groups says amalgam-related mercury vapor release may be highest during placement or removal of the filling. That detail matters for anyone weighing the health risks of mercury dental amalgam fillings, because the obvious response to a mercury scare is to have the filling drilled out.
What’s in a “silver” filling?
ATSDR describes the material as approximately 50% metallic mercury, 35% silver, 9% tin, 6% copper, and trace amounts of zinc. FDA calls it a mixture of mercury and a powdered alloy made up of silver, tin and copper. The name is misleading, since mercury makes up the largest share.
Mercury is not just filler material; it does a specific job in the mixture. FDA says mercury is used to bind the alloy particles together into a strong, durable, and solid filling, and that its unique properties, being a liquid at room temperature that bonds well with the alloy powder, make it an important component of dental amalgam. When a dentist prepares a filling, the encapsulated powdered alloy is mixed with the liquid mercury to form an amalgam putty, which is shaped in the prepared cavity and rapidly hardens into a solid filling.
The filling does not stay chemically quiet after it is placed. According to FDA, it releases small amounts of mercury vapor over time. FDA’s patient page says the amount depends on the number and age of existing fillings, and actions such as tooth grinding and gum chewing. The same page draws a distinction: there are no known health risks associated with ingestion of small amalgam particles, but inhaling the vapor may be harmful in certain patients.
How much does a filling add to a person’s total mercury exposure? ATSDR puts amalgam’s share at 0 to more than 75% of your total daily mercury exposure, depending on how many fillings a person has and how much fish they eat. FDA’s White Paper notes that mercury levels in blood, urine, and tissues correlate with the number of amalgam restoration surfaces.
Which groups does FDA consider high risk?
FDA’s September 24, 2020 announcement recommends that certain high-risk groups avoid getting dental amalgam whenever possible and appropriate. The groups named on FDA’s patient page are pregnant women or those planning to become pregnant, nursing mothers, children (especially those under the age of six), people with a known allergy to mercury, and people with neurological impairment or kidney dysfunction.
| High-risk group | What FDA’s patient page says |
|---|---|
| Pregnant or planning pregnancy | New fillings may cause transient mercury spikes |
| Nursing mothers | Breast milk mercury typically very low |
| Children under six | Studies very limited |
| Mercury allergy or sensitivity | Allergic reactions, oral ulcers reported |
| Neurological or kidney conditions | May be more susceptible |
The wording is careful. For pregnancy, studies found a relationship between a mother’s fillings and umbilical cord blood mercury but did not identify any certain associations with harmful health effects; however, the data is very limited. For young children, FDA notes that developing neurological systems may be especially sensitive. FDA’s guidance rests on uncertainty, not on proven harm. The suggested alternatives are composite resins and glass ionomer cement fillings.
Should existing amalgam fillings come out?
Here FDA’s advice changes direction. The agency is not recommending anyone remove or replace existing amalgam fillings in good condition unless it is considered medically necessary. Its reasoning: removal causes a temporary rise in vapor exposure and can cost healthy tooth structure, potentially resulting in more risks than benefits.
That advice covers high-risk groups too. FDA’s patient page says intact fillings in anyone, including those of greater risk such as pregnant or nursing mothers and children, should not be removed to prevent disease. People with mercury sensitivity or neurological or kidney disease should discuss the need for removal and replacement with their dentist or physician.
ATSDR’s guidance agrees. It says replacing all amalgam fillings just to avoid mercury is not recommended, because removal would actually expose the patient to a greater amount of mercury for a while. It adds that removal in people without adverse effects can put the person at greater risk, if performed improperly. So federal guidance on removal comes down to this: for an intact filling, the safest step is usually to leave it alone.
What decades of review have and haven’t settled
FDA says it has been reviewing the evidence on amalgam for over 20 years. The record shows a gradual shift in emphasis rather than a reversal.
| Date | Event | Impact |
|---|---|---|
| May 2006 | FDA requests NCTR assessment | Review of peer-reviewed studies published since 1997 |
| September 2006 | Assessment presented to advisory committees | Public scientific scrutiny |
| 2006 / 2009 | Draft White Paper plus 2009 Addendum | Together form FDA’s final White Paper |
| November 2019 | Immunology Devices Panel meeting | Concerns about cumulative exposure aired |
| September 24, 2020 | FDA recommendations for high-risk groups | Avoid new amalgam where possible and appropriate |
FDA’s White Paper review covered 34 articles and found no significant new information that would change the agency’s risk estimates. At the 2019 panel, though, speakers including those representing underserved communities raised concerns about mercury vapor from amalgam adding to dietary and environmental exposure.
FDA still lists open questions: long-term effects on high-risk groups, whether amalgam mercury can convert to other mercury compounds in the body, and whether mercury that builds up in tissues causes other effects. For the general population, the agency’s position is that most evidence shows the vapor doesn’t lead to harmful health effects for most people.
What this means for patients in 2026
FDA’s guidance on dental mercury exposure has two parts. For a new filling, people in a high-risk group should ask about non-mercury materials. FDA says amalgam use has generally declined over recent years as alternatives spread. For a filling that is already in place and intact, the guidance says to leave it. Removing it would create the vapor spike the guidance is meant to avoid.
Anyone who suspects a reaction to amalgam can report it to FDA’s MedWatch program at 1-800-332-1088 after talking with their dentist or physician.
Sources
- fda.gov – “FDA Issues Recommendations for Certain High-Risk Groups Regarding Mercury-Containing Dental Amalgam”
- archive.cdc.gov – “Mercury | Toxzine | ATSDR” (2019)
- atsdr.cdc.gov – “PUBLIC HEALTH STATEMENT MERCURY CAS#: 7439-97-6”
- fda.gov – “Information for Patients About Dental Amalgam Fillings | FDA” (2023)
- fda.gov – “White Paper: FDA Update/Review of Potential Adverse Health Risks Associated with Exposure to Mercury in Dental Amalgam | FDA” (2025)
- atsdr.cdc.gov – “Toxicological Profile for Mercury” (2024)
- fda.gov – “Dental Amalgam Fillings | FDA” (2023)