Dental Fillings Release Mercury After High-Strength MRI Scans
Strong magnetic field causes amalgam to discharge toxic metal.
Dental amalgam is a silver-colored material used to fill teeth that have cavities. Consisting of approximately 50 percent mercury, amalgam fillings can release mercury during the placement or removal process, or as a result of chewing, brushing or corrosion. A study published June 26 in the journal Radiology shows that dental amalgam also releases mercury after exposure to high-field-strength MRI.
The researchers opened cavities and placed amalgam fillings in 60 human molar or premolar teeth that had been extracted for various reasons. Nine days later, they placed the teeth in artificial saliva. Two groups of 20 teeth each underwent approximately 20 minutes of exposure to either 1.5-Tesla MRI or 7.0-Tesla MRI, while the remaining 20 teeth in the control group did not undergo MRI.
One day later, the researchers analyzed the artificial saliva for mercury content using inductively coupled plasma mass spectrometry. The mean mercury content of the artificial saliva was significantly higher in the 7.0-T MRI group at 673 micrograms per liter, compared to the 1.5-T MRI and control groups (172 and 141 micrograms per liter, respectively).
One important caveat is that the data do not reflect the amount of mercury that would be absorbed by various tissues in the body, limiting conclusions about the potential hazard to human health. According to the authors, further studies may be warranted to evaluate the relationship between high-field-strength MRI and the release of mercury from dental amalgam.