Summary safety review - Dental Amalgam - Assessing the Potential Risk of Negative Health Effects from Mercury

Review decision

A Summary Safety Review complements other safety related information to help Canadians make informed decisions about their use of health products. Each summary outlines what was assessed in Health Canada’s review, what was found and what action was taken by Health Canada, if any.


Issued: 2021-03-31

Product

Dental Amalgam

Potential Safety Issue

Negative health effects from mercury

Key Messages

  • In Canada, dental amalgam is a medical device used to replace broken or decayed areas of teeth, such as cavities.
  • In 1996, Health Canada published a position statement1 that recommended minimizing the use of amalgam in children, pregnant women and patients with kidney disease. In 2020, Health Canada reviewed recent information to determine if the recommendations in the 1996 report are still valid.
  • Health Canada's 2020 review concluded that there is no clear link between mercury in dental amalgam and negative health effects. However, bulk (loose) dental amalgam powders, which have to be mixed with liquid mercury by hand, are known to pose an unnecessary risk of mercury exposure for the dental healthcare professional. The 1996 Health Canada position statement on dental amalgam remains appropriate. Health Canada's findings are consistent with the conclusions of professional dental associations and international regulatory agencies.
  • Health Canada has worked with manufacturers to discontinue the licenses of bulk dental amalgam powders in Canada.

Overview

Dental amalgam is used to replace broken or decayed areas of teeth, such as cavities. Dental amalgam contains mercury. Mercury can have negative effects on health, including brain and kidney function.

In 1996, Health Canada published a report2 on the safety of dental amalgam. That report included a position statement with recommendations following a detailed review. The position statement1 drew no clear link between mercury in dental amalgam and negative health effects, but advised minimizing the use of dental amalgam in children, pregnant women and patients with kidney disease, as a precaution.

A safety review was conducted in 2020 as a follow-up to consider recent information and determine if the recommendations in the 1996 report are still valid.

Use in Canada

  • Dental amalgam has been used in Canada for over 100 years to replace broken or decayed areas within teeth, such as cavities. At the time of the 2020 review, there were 46 dental amalgam products authorized for sale in Canada.
  • Dental amalgam is a mixture of liquid mercury and a metal powder composed of silver, tin and copper. Typically, these come in closed capsules that already contain measured amounts of the metal powder and mercury. The metal powder and mercury are mixed by placing the entire capsule in specially designed equipment.
  • Dental amalgam products with bulk (loose) metal powder separate from the liquid mercury are also available. In this case, the metal powder and liquid mercury have to be mixed manually by the dental healthcare professional. At the time of the 2020 review, six products containing bulk metal powder were authorized for sale in Canada. However, they were not being used in Canada.
  • The use of dental amalgam for the repair of decayed or broken teeth is decreasing in Canada.

Safety Review Findings

  • Health Canada reviewed information from incident reports, medical and scientific literature, and information published by international regulatory agencies.
  • A search of the medical device incident reporting databases in Canada and the United States (U.S.) identified 2 Canadian casesa and 49 cases in the U.S. over the past 25 years, describing negative health effects potentially related to the use of dental amalgam. There was not enough information in the reports to support a link between the symptoms (double vision, imbalance, weakness) and dental amalgam.
  • Health Canada also reviewed 29 articles published between 2014 and 2019. Overall, the review did not find evidence to support a clear link between the use of dental amalgam and negative health effects from mercury. However, children, pregnant women, and patients with kidney disease may be more vulnerable to the effects of mercury.
  • The safety of dental amalgam has been reviewed by organizations both within Canada and internationally, including the Canadian Agency for Drugs and Technologies in Health (CADTH), the U.S. Food and Drug Administration (FDA), and the European Commission's Scientific Committee on Emerging and Newly Identified Risk (SCENIHR). The general consensus is that the available information does not support a clear link between the use of dental amalgam and negative health effects.
  • The Canadian and American Dental Associations maintain that dental amalgam is safe for the repair and restoration of teeth.

Conclusions and actions

  • Health Canada's 2020 review of the available safety information concluded that there is no clear link between mercury in dental amalgam and negative health effects.
  • This safety review did not find new evidence to suggest a change in the overall safety profile for dental amalgam. Therefore, the 1996 Health Canada position statement1 on dental amalgam remains valid. As a precaution, use of dental amalgam in children, pregnant women, and patients with kidney disease should be minimized, as recommended in the 1996 Health Canada position statement.
  • Although pre-measured dental amalgam capsules are considered safe, bulk dental amalgam powders, which have to be mixed with liquid mercury by hand, are known to pose an unnecessary risk of mercury exposure for the dental healthcare professional. Following its safety review, Health Canada worked with manufacturers to discontinue the licenses of bulk dental amalgam powders in Canada.
  • Health Canada will continue to monitor information on the benefits and risks associated with the use of dental amalgam and take appropriate and timely action should any new health risks be identified.

Additional information

The analysis that contributed to this safety review included scientific and medical literature, Canadian and international incident reports, and what is known about the use of these medical devices both in Canada and internationally.

Following the completion of the safety review by Health Canada, the U.S. FDA published an updated safety communication in September 2020 outlining recommendations for certain high-risk groups regarding mercury-containing dental amalgam. The findings of our risk assessment on dental amalgam are consistent with this recent communication by the FDA, as well as with recommendations from other international regulatory agencies.

For additional information about Health Canada's assessment of medical devices, contact the Medical Devices Directorate.

References

  1. The Safety of Dental Amalgam, II. Health Canada Position Statement on Dental Amalgam
  2. The Safety of Dental Amalgam

Footnotes

  1. Canadian reports can be accessed through Health Canada's Medical Device Incidents page.

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