[Study on the significance of mercury accumulation in the brain from dental amalgam fillings through direct mouth-nose-brain transport].

The transport of mercury (Hg) from the oro-nasal to the cranial cavity via a direct route was investigated. In 55 deceased persons, Hg concentrations were measured in the olfactory bulb and the trigeminal ganglion, and the number of dental amalgam fillings was assessed. For the purpose of comparison, Hg concentrations were also determined in the occipital lobe cortex, the pituitary gland and the kidney cortex. Quantitative Hg analysis was performed by cold vapor atomic absorption spectroscopy after acid digestion using high pressure microwave treatment. In the olfactory bulb (geom. mean 17.4 micrograms/kg w. w.), the Hg concentration was significantly higher than in the occipital lobe cortex (geom. mean 9.2 micrograms/kg w. w.) (p < 0.0001). No significant difference was found between the Hg concentration in the trigeminal ganglion (geom. mean 12 micrograms/kg w. w.) and the occipital lobe cortex (alpha = 0.005; p = 0.0342). Regression analysis did not reveal a statistically significant correlation between the number of dental amalgam fillings and the Hg content in the olfactory bulb and the trigeminal ganglion, respectively (alpha = 0.01). Therefore, these results do not support the hypothesis of a significant flow o Hg from dental amalgam fillings to the cranial cavity by a direct oro-nasal route. In contrast, a statistically significant correlation exists between the number of dental amalgam fillings and the Hg concentration in the kidney cortex (r2 = 0.317; p < 0.0001), and, to a lesser extent, the Hg concentration in the occipital lobe cortex (r2 = 0.17; p = 0.0016). The highest Hg concentrations (geom. mean 93.1 micrograms/kg w. w.) were detected in the kidney cortex, followed by the pituitary gland (geom. mean 30.0 micrograms/kg w. w.). In this study, Hg concentration in the pituitary gland did not correlate with the number of dental amalgam fillings.