Mercury deposits in neurons of the trigeminal ganglia after insertion of dental amalgam in rats.

An amalgam filling was inserted into the first upper molar of 12 rats and the animals were killed after 3-9 months. Tissue sections from the trigeminal ganglia and the brain stem were then investigated with a sensitive histochemical technique to trace mercury deposits. Within the trigeminal ganglia, nerve cells with mercury deposits were observed in seven out of 12 rats, whereas no mercury was detected in sections from the brain stem. The mechanism responsible for the accumulation of mercury in neurons of the trigeminal ganglia is discussed.