Fluorescence finds mercury in dental amalgam

Researchers at the University of Pittsburgh have developed what they say is a simple and quick method for detecting mercury in dental amalgam, according to a university press release.

The technique involves a fluorescent substance that glows bright green when it comes into contact with oxidized mercury, the researchers report in the current online edition of the Journal of the American Chemical Society. The intensity of the glow indicates the amount of mercury present.

Developed in the laboratory of Kazunori Koide, a chemistry professor in the university's School of Arts and Sciences, the new method can be used onsite and can detect mercury in 30 to 60 minutes for dental fillings, Koide explained.

To test for mercury leaching in dental amalgams, the research team pressed a cloth onto a tooth containing an amalgam filling for one minute, then exposed it to a mercury-detecting agent. The resulting fluorescence came from the reaction of mercury ions with hydrocarbons called alkynes; the alkyne is converted into a ketone and creates a fluorescent molecule.

The researchers also submerged two amalgam-filled teeth in the amino acid cysteine to mimic sulfur-rich foods, which are thought to increase mercury seepage from amalgam. Again, the cysteine solution turned bright green when the indicator was added, suggesting that this method could also be used to monitor mercury leaching caused by sulfur-rich food.

Koide suggested that his method could also be used to test dentist office wastewater for mercury content onsite without sending samples to analytical laboratories.