Ask the Expert: What Do I Need to Know About Silver Fillings?

Dr. Jennifer Webster-Cyriaque

Read the Q&A with National Institute of Dental and Craniofacial Research (NIDCR) Acting Director Jennifer Webster-Cyriaque, D.D.S., Ph.D., who answers common questions about silver-colored tooth fillings, also known as dental amalgam fillings.

What is dental amalgam?

Although commonly called “silver” fillings, dental amalgam is a mixture of metals including mercury, silver, tin, copper, and zinc used to fill cavities in teeth. Dentists have been using dental amalgam to fill cavities from tooth decay—one of the world’s most common diseases1 —for more than 150 years. One study estimates that over half of restored permanent teeth in the U.S. contain dental amalgam fillings.2

Why is mercury used in dental amalgam fillings?

Mercury has unique properties that make it ideal for use in a filling material. It is liquid at room temperature and binds with powdered metals to form a durable solid.3 Dental amalgam fillings are made up of about 50% mercury.3

What are the benefits of dental amalgam?

Dental amalgam is strong, long-lasting, and cost-effective. Fillings made from dental amalgam are also easier to place. While other filling materials do not bond well to the tooth in the presence of saliva, dental amalgam does not have this problem. Additionally, amalgam forms a tight seal that helps prevent bacteria from entering the site and causing infection. Dental amalgam is also better suited to treat larger cavities compared to other materials because it is stronger and can withstand significant forces.4

Are there concerns with using dental amalgam fillings?

Dental amalgam fillings can expose patients to low levels of mercury in the form of vapor when they are placed or removed. They can also release small amounts of vapor during chewing.5 But it’s important to know that current evidence does not show that exposure to mercury from dental amalgam is harmful to your health.3

Additionally, dental health care professionals can be exposed to mercury if the filling material is not prepared and used properly.6

Mercury poses a risk to the environment. When dental amalgam is used to treat cavities or when old amalgam is removed from teeth for additional repair, dentists are required to use specialized equipment, an amalgam separator, to dispose of excess dental amalgam separately from other waste.7 This ensures that mercury will not contaminate wastewater or enter the solid waste stream.6 Mercury collected this way can be recycled.7

There is a global push to protect both human health and the environment from mercury.6 Many countries, including the U.S., are working to reduce the use of dental amalgam and exploring other filling materials that do not include mercury.6 Some countries, including Norway and Sweden, have eliminated amalgam use, transitioning to environmentally safe alternatives.8,9

What does research tell us about the safety of dental amalgam?

Studies show that dental amalgam fillings are safe for most people.

The U.S. Food and Drug Administration (FDA) reviewed over 100 mercury studies in 2019.10 They found being exposed to small amounts of mercury from dental amalgam fillings does not pose health risks to the general population.10 Organizations such as the American Dental Association11 and the International Association for Dental, Oral, and Craniofacial Research12 confirm that dental amalgam is safe for filling cavities in the general population.

In 2021 the University of Rome published a review of 9 studies on dental restorations and the risk for various diseases.13 While mercury exposures in young children may pose neurodevelopmental risks, the review found that patients with dental amalgam fillings did not have a higher risk for certain conditions compared to patients with fillings made from other materials.13 The studies looked at memory, presence of tremors, IQ scores, and childhood behavior, among other conditions.13  Additionally, studies funded by NIDCR have found no differences in kidney function or performance on IQ tests among children with dental amalgam fillings versus other types of fillings.14-16

Are there people who shouldn’t get dental amalgam fillings?

While dental amalgam fillings are safe for most people,17 small amounts of mercury may pose a health risk to certain groups of people, including pregnant or nursing women, young children, and people with neurological disease, impaired kidney function, or sensitivity to mercury or other components of dental amalgam.18 High-risk populations should avoid getting dental amalgam whenever possible.18 Mercury-free materials like glass ionomers or composite resins are recommended for pregnant women and children.18

I already have dental amalgam fillings. Should I have them removed?

No. The FDA does not recommend that you remove fillings if they are intact.17 Removing mercury-containing fillings can release mercury vapor. This can expose you to more mercury compared to leaving the filling in place. If you belong to a high-risk group, talk to your dentist about other available options.

What other materials can be used to fill cavities and how do they compare to dental amalgam?

“Tooth-colored” fillings are more natural looking and are commonly used to fill cavities instead of dental amalgam. Two of these more common fillings are made of composite resin or glass ionomer cement:4

  • Composite resin fillings are made of plastic and powdered glass. They are more expensive than dental amalgam. They are also trickier to place since they may not bond to the tooth as well in the presence of saliva.
  • Glass ionomer cement fillings are made of powdered glass and other materials. Unlike dental amalgam, they are not good for filling large cavities.

Both types of tooth-colored fillings are less durable than dental amalgam fillings, making them more susceptible to breakage and potential reinfection of the tooth. Research funded by NIDCR found that among more than 700,000 tooth-colored fillings in the U.S., 16% failed within five years of being placed. Most failed due to cavities (53%) or because the tooth broke or fractured (23%).19

Alternatives to dental amalgam are continuously improving. Materials under development include composites that promote enamel repair and prevent bacteria from accumulating.20 Improved curing techniques are helping to make composite resin last longer. Because composite resins can contain bisphenol A (BPA), a chemical that can negatively affect children’s health,21, 22 scientists are developing new resins and materials that do not contain BPA.

What research is NIDCR doing on dental filling materials?

Researchers are working on developing better alternatives to dental amalgam. NIDCR has funded research that aims to create new mercury-free filling materials that are cost-effective, durable, and safe for everyone to use, including groups who are advised against using dental amalgam. NIDCR has also funded research on developing new longer-lasting, water-resistant dental filling material that can prevent bacteria from collecting on surfaces in the mouth, compared to currently used materials.23

In September 2024, NIDCR awarded the American Dental Association Forsyth Institute $6.2 million over five years to develop new materials to use as dental fillings.24 These “smart” materials will be designed to detect and address changes in the mouth to protect fillings and teeth. For example, if a filling begins to crack, the material will be able to detect the crack and release agents to repair and strengthen itself.

References

  1. World Health Organization (WHO). Oral health [Internet]. Geneva: WHO; 2025 Mar.
  2. Estrich CG, Lipman RD, Araujo MW. Dental amalgam restorations in nationally representative sample of US population aged ≥ 15 years: NHANES 2011–2016. J Public Health Dent. 2021 Dec;81(4):327-330. doi: 10.1111/jphd.12456. Epub 2021 May 5.
  3. U.S. Food and Drug Administration (FDA). Dental amalgam fillings [Internet]. Silver Spring (MD): FDA; 2021.
  4. FDA. Treatment options for dental caries [Internet]. Silver Spring (MD): FDA; 2020.
  5. United States Environmental Protection Agency (EPA). Mercury in dental amalgam [Internet]. Washington (DC): EPA; 2025 Feb.
  6. Fisher J, Varenne B, Narvaez D, Vickers C. The Minamata Convention and the phase down of dental amalgam. Bull World Health Organ. 2018 Jun 1;96(6):436-438. doi: 10.2471/BLT.17.203141. Epub 2018 May 14.
  7. EPA. Dental effluent guidelines [Internet]. Washington (DC): EPA; 2025 Apr.8.
  8. Kopperud SE, Staxrud F, Espelid I, Tveit AB. The post-amalgam era: Norwegian dentists’ experiences with composite resins and repair of defective amalgam restorations. Int J Environ Res Public Health. 2016 Apr 22;13(4):441. doi: 10.3390/ijerph13040441.
  9. European Network for Environmental Medicine. Global overview of countries phasing out dental amalgam [Internet]. Berlin: European Network for Environmental Medicine; 2025 Jan.
  10. FDA. Epidemiological evidence on the adverse health effects reported in relation to mercury from dental amalgam [Internet]. Silver Spring (MD): FDA; 2019 Sep.
  11. American Dental Association (ADA). The American Dental Association reaffirms its position on dental amalgam [Internet]. Chicago (IL): ADA; 2020 Sep.
  12. International Association for Dental, Oral, and Craniofacial Research (IADR). Safety of dental amalgam [Internet]. Alexandria (VA): IADR; 2021 Aug.
  13. Gallusi G, Libonati A, Piro M, Di Taranto V, Montemurro E, Campanella V. Is dental amalgam a higher risk factor rather than resin-based restorations for systemic conditions? A systematic review. Materials (Basel). 2021 Apr 15;14(8):1980. doi: 10.3390/ma14081980.
  14. Bellinger DC, Trachtenberg F, Barregard L, Tavares M, Cernichiari E, Daniel D, et al. Neuropsychological and renal effects of dental amalgam in children: A randomized clinical trial. JAMA. 2006 Apr 19;295(15):1775-1783. doi: 10.1001/jama.295.15.1775.
  15. DeRouen TA, Martin MD, Leroux BG, Townes BD, Woods JS, Leitão J, et al. Neurobehavioral effects of dental amalgam in children: A randomized clinical trial. JAMA. 2006 Apr 19;295(15):1784-1792. doi: 10.1001/jama.295.15.1784.
  16. Bellinger DC, Daniel D, Trachtenberg F, Tavares M, McKinlay S. Dental amalgam restorations and children’s neuropsychological function: The New England Children’s Amalgam Trial. Environ Health Perspect. 2007 Mar;115(3):440-446. doi: 10.1289/ehp.9497. Epub 2006 Oct 30.
  17. FDA. Dental amalgam fillings recommendations - graphics [Internet]. Silver Spring (MD): FDA; 2021 Feb.
  18. FDA. FDA issues recommendations for certain high-risk groups regarding mercury-containing dental amalgam [Internet]. Silver Spring (MD): FDA; 2020 Sep.
  19. Thyvalikakath T, Siddiqui ZA, Eckert G, LaPradd M, Duncan WD, Gordan VV, et al. Survival analysis of posterior composite restorations in National Dental PBRN general dentistry practices. J Dent. 2024 Feb;141:104831. doi: 10.1016/j.jdent.2024.104831. Epub 2024 Jan 7.
  20. Zhou W, Chen H, Weir MD, Oates TW, Zhou X, Wang S, et al. Novel bioactive dental restorations to inhibit secondary caries in enamel and dentin under oral biofilms. J Dent. 2023 Jun;133:104497. doi: 10.1016/j.jdent.2023.104497. Epub 2023 Apr 1.
  21. Marzouk T, Sathyanarayana S, Kim AS, Seminario AL, McKinney CM. A systematic review of exposure to Bisphenol A from dental treatment. JDR Clin Trans Res. 2019 April;4(2):106-115. doi: 10.1177/2380084418816079. Epub 2019 Jan 25.
  22. Ejaredar M, Lee Y, Roberts DJ, Sauve R, Dewey D. Bisphenol A exposure and children's behavior: A systematic review. J Expo Sci Environ Epidemiol. 2017 Mar;27(2):175-183. doi: 10.1038/jes.2016.8. Epub 2016 Mar 9.
  23. National Institutes of Health (NIH). Novel polymeric materials with improved durability in the oral environment: Tailoring responses to host and bacterial enzymes with anti-proteolytic and ecology-based antimicrobial approaches [Internet]. Bethesda (MD): NIH; 2019.
  24. ADA. NIH awards ADA Forsyth over $6 million to design AI-driven amalgam replacement for dental restoratives [Internet]. Chicago (IL): ADA; 2024 Sep.
Last Reviewed
June 2025