Mercury Dental Fillings
- Christine Daecher, DO
- Oct 30, 2024
- 4 min read
Updated: 6 days ago
Sliver-colored dental fillings or dental amalgams contain mercury (Hg) and are known to release mercury vapors. Should you have them removed?
About Silver-Colored Fillings
Mercury amalgams—commonly called silver fillings—contain approximately 50% mercury, 30% silver, 14% tin, and 8% zinc. They are known as mercury amalgams because mercury is their primary component.
Historically, it was believed that a protective oxide layer formed over the amalgam surface, preventing mercury release and making the filling safe. However, research over the past several decades has demonstrated that this assumption is not accurate.
Mercury Vapor Release
With every manipulation of a tooth containing an amalgam, mercury vapor is released. Studies have shown the following approximate levels of vapor release:
Dry polishing at the dentist: ~600 µg of mercury vapor per cubic meter of air
Wet polishing: ~500 µg/m³
Bruxism (teeth grinding): ~350 µg/m³
Toothbrushing: ~200 µg/m³ (400 µg total per day if brushing twice)
Chewing: ~36 µg/m³
These vapors are inhaled and absorbed through the lungs. Hot meals and beverages significantly increase the amount of vapor released compared to cold foods.
How This Compares to WHO’s Safety Limits
The World Health Organization (WHO) states that a “safe” level of long-term daily mercury inhalation is 2 µg per kilogram of body weight.
For a 150 lb (68 kg) adult, this equals 136 µg per day (68 × 2).
If this person eats three meals and brushes their teeth twice daily, and all released mercury were absorbed (a theoretical assumption), total exposure would be approximately:
(36 × 3) + (200 × 2) = 508 µg/day
That’s 372 µg above the WHO’s recommended limit.
With two amalgams, exposure could reach roughly 1,016 µg/day.
With three amalgams, about 1,524 µg/day.
While actual absorption is likely lower, these numbers suggest a concerning potential exposure.Older amalgams that appear dark or blackened—rather than shiny silver—are oxidizing and tend to release even greater amounts of mercury vapor.
Should Dental Amalgams Be Banned?
Several countries have already taken action:
2011: Sweden, Norway, Denmark, and Germany banned dental amalgams.
2018: All European Union countries banned amalgam use in children under age 15.
2019–2025: Ireland, Finland, and Slovakia set timelines to fully eliminate amalgam use.
As of 2021, at least 41 countries have banned mercury amalgams altogether.
In contrast, the United States continues to allow their use. The American Dental Association (ADA) maintains that amalgams are “safe, affordable, and durable,” despite acknowledging that mercury vapor is released.
Notably, when placing an amalgam filling, more healthy tooth structure must be removed because amalgams do not bond to enamel as effectively as modern composite materials.
On September 24, 2020, the FDA recommended avoiding amalgam placement in:
Pregnant women and those planning pregnancy
Nursing mothers
Children under 6 years
People with preexisting neurologic or kidney disease
Individuals allergic or sensitive to mercury
In response, the ADA reiterated its position, again stating that amalgams are “safe, affordable, and durable.”1, 2
Mercury in the Body
Mercury is known to accumulate in the brain, kidneys, and other tissues—the origin of the term “Mad Hatter disease.”
In the kidneys, mercury can cause damage leading to hypertension and chronic kidney disease. It is absorbed through oral tissues, swallowed saliva, and inhaled vapors. Multiple studies demonstrate that blood mercury levels correlate directly with the number of amalgam fillings present.
In contrast, white composite restorations contain BPA, but urinary BPA levels have not been shown to correlate with the number of composite fillings. Composites release small amounts of BPA for about two weeks after placement, after which release becomes negligible.
Genetic Susceptibility
Individuals carrying the ApoE4 allele—associated with higher Alzheimer’s disease risk—also exhibit reduced mercury detoxification capacity. Those with the ApoE2 allele tend to detoxify mercury more efficiently and have a lower Alzheimer’s risk.
Microbiome and Metal Exposure
Animal studies demonstrate that mercury amalgams can alter the oral and gut microbiome. Genomic analyses show that exposure to toxic metals promotes multi-antibiotic resistance, as bacteria adapt to metals’ antimicrobial properties, leading to cross-resistance against antibiotic medications.3,4
Allergic and Inflammatory Reactions
Individuals with metal or mercury allergies may experience chronic oral inflammation or mucosal irritation from amalgams.
Removing Amalgams
Unfortunately, removing mercury amalgam fillings is not as simple as visiting a general family dentist. During unsafe removal, each amalgam can release up to 1,000 µg (micrograms) of mercury vapor per cubic meter of air into the surrounding environment.
Dentists are well aware of the dangers posed by mercury vapors and airborne particulate matter generated during drilling. Specialized safety protocols must be followed to protect both the patient and dental staff.
These precautions typically include:
Dental staff wearing 3M-rated vapor/gas respirators specifically approved for mercury vapor protection.
The patient being provided with negative air pressure suction to capture airborne mercury.
Use of nasal oxygen or clean-air masking to prevent inhalation of vapors.
High-volume evacuation systems, rubber dams, and copious water irrigation to minimize aerosolization.
Because of these requirements, the cost of safe amalgam removal can be significant—and is rarely covered by dental insurance.
Some individuals consider medical or dental tourism for this procedure; however, this should only be done after confirming that the provider follows certified mercury-safe protocols such as those outlined by the International Academy of Oral Medicine and Toxicology (IAOMT).
References:
1 U.S. Food and Drug Administration (FDA). “Recommendations about the use of dental amalgam.” September 24, 2020.
3 Various genomic studies on metal-induced antibiotic resistance (details available upon request).
4 Wiggins AG, LaVoie SP, Wireman J, Summers AO. Thinking outside the (pill) box: Does toxic metal exposure thwart antibiotic stewardship best practices? Plasmid. 2018 Sep;99:68-71. doi: 10.1016/j.plasmid.2018.08.003. Epub 2018 Sep 4. PMID: 30193909.
5 Photo credit: Hahn, et. al., 1989
Comments