The purpose of this study is to clarify the effect of hypoxia condition for the three-dimensional culture using radial-flow bioreactor (RFB). We cultured osteoblastic cells using RFB in hypoxic condition at 37°C, pH 7.4, DO 2.60 ppm and with the culture medium circulating at 3 mL/min. For normal cultivation, cells were cultured in the same manner with DO 6.86ppm. For single cultivation, cells were cultured in a collagen sheet at 37°C under 5% CO₂. After one week of hypoxic cultivation, cells showed only 2-fold increase throughout the three-dimensional scaffolds, despite cells showed 5-fold increase throughout the three-dimensional scaffolds under normal cultivation. A significant difference in number of cells was noted between under hypoxic cultivation and normal cultivation No significant difference was observed in number of cells between under hypoxic cultivation and single cultivation. These results revealed that the hypoxic condition disturbed cell proliferation on the three-dimensional culture of osteoblasts using RFB.

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We compared the structure, composition, and crystal between subgigival dental calculus and dental calculus of periodontal lesion combined with endodontic lesion. In the dental calculus of periodontal lesion combined with endodontic lesion, spherical structures were commonly observed. EPMA analysis revealed calculus composition to be, in decreasing amounts, Ca, P, Na and Mg. The dental calculus of periodontal lesion combined with endodontic lesion contained S and Al, with Si and Fe detected as trace element. The Ca/P molar ratio was 1.52 on average in the dental calculus of periodontal lesion combined with endodontic lesion and its value was similar to W. The Ca/P molar ratio was 1.50 on average in the older group and its value was similar to W. The Ca/P molar ratio was 1.75 on average in the younger group and its value was similar to HA. HA was detected in the younger group, and W was detected in both the dental calculus of periodontal lesion combined with endodontic lesion and the older group by X-ray diffraction method.

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