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Some toy badges that we obtained emitted fluorescence strongly, when there were irradiated by an ultra violet lamp in a darkroom. They were left on X ray negative films for several hours and one of them blackened films. Owing to these facts, we doubted if it is a radioactive material. In order to search if it is a radioactive material or not, a portion of the badge paint was examined by a liquid scintillation analyzer and an ammeter which is connected to a photo diode. Consequently, the badge paint was not identified a radioactive material. Then, to find the reason why some badges emitted under an ultra violet lamp and one badge paint blackened X ray negative films, neutron activation analysis was applied to the badge paint sample. As a result, we finally found that the badge paint was made of phosphorescent phosphor because it contains aluminum.

The concentration of Fe, Zn and Co in caries teeth was determined by neutron activation analysis to compare with those of complete impacted wisdom teeth. In order to investigate the distribution of three elements, molar teeth were separated not by conventional method like precipitation or UV absorption method but by ashing method. Furthermore, the same elements for dental pulp and softened dentin were determined. The following results were obtained.1. The concentration of three elements (Fe, Zn and Co) in enamel, dentin and cementum of caries teeth was higher than that in control teeth.2. Enamel contained more Fe and Co than those in dentin or cementum, whereas Zn was found to be evenly distributed in three parts of the teeth.3. The concentration of the elements was Zn>Fe>Co in softened dentin, Fe>Zn>Co in dental pulp.

4-Bromophenacyl bromide (BPB) is generally used as a phospholipase A(2) (PLA2) inhibitor. In the present study, we demonstrate that BPB induces Ca2+ influx in human gingival fibroblasts. In fura-2-loaded human gingival fibroblasts, BPB evoked a transient increase in intracellular Ca2+ concentration ([Ca2+]i) in a dose-dependent manner. The BPB-induced Ca2+ mobilization was also shown in a single fluo-3-loaded-fibroblast. The BPB-induced increase in [Ca2+]i was completely abolished by the elimination of the external Ca2+. Ca2+ influx induced by the Ca2+-mobilizing agonist histamine was markedly enhanced in the presence of BPB. These suggest that the BPB-induced Ca2+ mobilization is due to the influx of extracellular Ca2+. However, it is unlikely that the effect of BPB is dependent on the inhibition of PLA2 activity, because other PLA2 inhibitors, such as AACOCF3, quinacrine dihydrochloride and manoalide, failed to induce Ca2+ mobilization. Chemical compounds similar to BPB, but which have no -CH2-Br at position 1 in the benzene ring failed to evoke Ca2+ mobilization, indicating that the position of -CH2--Br in BPB is important for causing the Ca2+ influx.

In this paper, we used the extracts from cementum, bone, dentin and enamel, and compared the chemotactic behavior of human periodontal ligament (HPDL) cells, human gingival fibroblasts (HGF) and human alveolar bone (HAB) cells using modified Boyden chambers. The extracts, obtained using 4 M guanidine HCl (“G” extract), from cementum, root dentin, and bone had greater chemotactic effects than all the 4 M guanidine HCl/0.5 M EDTA extracts (“E” extract). HPDL cells and HGF exhibited higher chemotactic behavior than osteoblast-like HAB cells in response to cementum and root dentin “G” extracts. On the other hand, HAB cells showed the highest migratory activity in response to the bone “G” extract. The chemotactic activities of these extracts were reduced by heat- and trypsin-treatment. These results suggest that proteinaceous chemotactic factors exist in the cementum, root dentin and bone, and they appear to regulate the migration and orientation of HPDL cells, HGF and HAB cells during periodontal wound healing.

The cell cycle and cell renewal time of the tongue epithelium in C3Hf/He mice were studied by the pulse labelling method.The cell cycle was 28.0 hours for the dorsal and 26.0 hours for the ventral surface of the tongue.The average turnover of the tongue epithelium was 9-10 days.

Porcelain teeth, some of which contained uranium compounds for aesthetic purpose, have been widely used in dental clinics. Recently, the hazardous effects by uranium radiation were suggested.In the present study, the authors carried out the determination of uranium concentrations of four major brands of porcelain teeth marketed in Japan using the fission track method, and the absorbed doses of oral tissues were calculated by the authors' introduced formula for calculation of alpha radiation.Average uranium concentrations of the brands studied were determined 3.6ppm (0.33-10ppm, Japan), 18ppm (0.69-81ppm, Japan), 9.4ppm (2.5-14ppm, Japan) and 82ppm (11-205ppm, U. S. A.), respectively. The corresponding dose equivalents at the surface of oral mucosal membrane were 2.9rem y-1, 14rem y-1, 7.6 rem y-1 and 66rem y-1.

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.

The uranium content of several human tooth, bone and soft tissue samples was determined by the fission tract method. The average uranium content in teeth, bones and soft tissues were 6.7, 8.4 and 64 ppb ash, respectively. The distribution of uranium in bones is less uniform than that of teeth, and the uranium content of soft tissues is generally higher than that of teeth and bone. The presence of thorium does not interfere with the uranium determination in most cases.

Porcelain teeth, some of which contained uranium compounds for aesthetic purpose, have been widely used in dental clinics. Recently, the hazardous effects by uranium radiation were suggested.In the present study, the authors carried out the determination of uranium concentrations of four major brands of porcelain teeth marketed in Japan using the fission track method, and the absorbed doses of oral tissues were calculated by the authors' introduced formula for calculation of alpha radiation.Average uranium concentrations of the brands studied were determined 3.6ppm (0.33-10ppm, Japan), 18ppm (0.69-81ppm, Japan), 9.4ppm (2.5-14ppm, Japan) and 82ppm (11-205ppm, U. S. A.), respectively. The corresponding dose equivalents at the surface of oral mucosal membrane were 2.9rem y-1, 14rem y-1, 7.6 rem y-1 and 66rem y-1.