Dental Amalgam Fillings Show No Link to Primary Sjögren’s, Study Reports

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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No connection is evident between exposure to the dental amalgam used to fill cavities and the risk of developing Sjögren’s syndrome,  a study by researchers in Taiwan reported.

The study, “Analysis of dental amalgam fillings on primary Sjögren’s syndrome,” was published in Medicine

Dental amalgam is the silvery material that is used to fill in cavities. Typically, it contains silver alloys and mercury.

It is not known exactly what causes Sjögren’s syndrome — a person’s genetic makeup likely plays a role, and exposure to environmental toxins may also influence the disease’s development. Mercury is well-established to have toxic effects on the body if ingested in substantial amounts, and there is some evidence that tiny amounts of mercury can leach out of dental amalgam over time.

Such leaching, in theory, could mean that people with amalgam fillings might be at higher risk of Sjögren’s, but such a link has not before been tested.

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A trio of scientists in Taiwan conducted an analysis of data using that country’s national insurance database. They identified 5,848 people newly diagnosed with primary Sjögren’s syndrome (meaning Sjögren’s that is not related to another health condition), and an equal number of people without the disease to serve as controls.

In both groups, participants average age was about 58, and over two-thirds of the patients were female. Other demographic and clinical factors, including where people lived, income levels, and co-occurring health conditions were similar in both groups.

Researchers conducted statistical analyses to test whether more primary Sjögren’s patients than controls had been exposed to amalgam fillings, as such a finding would suggest that these fillings can increase Sjögren’s risk.

Results showed no difference in amalgam filling exposure between the two groups. Further analyses stratified by sex also failed to identify any connection between amalgam filling exposure and Sjögren’s risk.

“To the best of our knowledge, this case-control study is the first to use nationwide, population-based longitudinal administrative data to examine the association between AMF [amalgam filling] and pSS [primary Sjögren’s syndrome],” the researchers concluded. “The findings show that people with AMF were not at a higher risk of pSS in Taiwanese population.”

They noted that this study’s design has limitations: insurance data is at best an imperfect proxy for clinical realities, and it does not include important data such as lifestyle habits.

The team also noted a broader need for more research into connections between environmental exposures and Sjögren’s risk.