[Distribution of uranium in dental porcelains by means of the fission track method (author's transl)].

Porcelain teeth, some of which contain uranium compounds for aesthetic purpose, have been widely used in dental clinics. Hazardous effects due to uranium radiation have been suggested by recent publications. In the previous study, the authors reported the uranium content of porcelain teeth and radiation dose by it. In this study, using the fission track method, the authors examined spatial distribution of uranium in dental porcelain teeth (4 brands) which were marketed in Japan. From each sample of porcelain tooth, a 1-mm-thick specimen was sliced, and uranium content was measured at every 0.19 mm from labial side to lingual side for making a uranium distribution chart. Higher uranium concentration was found in Trubyte Bioblend porcelain teeth (USA) and they showed almost uniform distribution of uranium, while those of the Japanese three brands indicated, in most case, comparatively lower concentration and found to be non-uniform distributions. Range of uranium concentration in these brands were N.D. approximately 5.2 ppm (Shofu-Ace), N.D. approximately 342 ppm (Shofu-Real), N.D. approximately 47 ppm (G.C. Livdent) and N.D. approximately 235 ppm (Trubyte Bioblend), respectively.