Osteoprotegerin (OPG) is a secreted member of the TNF recepter superfamily that negatively regulates osteoclastgenesis through inhibition of RANKL and RANK interaction. We histologically examined the effects of local OPG administration on alveolar bone resorption during experimental tooth movement in rats, and found that OPG administration might regulate bone resorption through inhibition of osteoclast differentiation and function. Elastic band was inserted between the upper first and second molars of 8-week-old Wistar rats for 1 or 4 days. OPG was locally given (0.3 mg/kg) to the buccal and/or palatal periodontal ligament (PDL) between molars at every 1 or 4 days. Localization TRAP and RANKL, the number and structure of osteoclasts (OC), and the alveolar bone volume around molars were histologically examined. At 4 days after tooth movement, many TRAP-positive OC appeared along the alveolar bone surfaces of both OPG administered and saline-administered control sides, but the number of OC per unit bone area and bone surface length at the OPG administered side was significantly fewer than that at the control side. In OPG administered side, most OC showed immature ruffled border structure and expressed decreased vacuolar-type H₊-ATPase activity. On day 4, RANKL was similarly expressed in the PDL interstitial cells and OC in both OPG administered and control sides. However, up to day 4, there was no significant difference in alveolar bone volume between OPG administered and control sides. These results suggest that local OPG administration may regulate alveolar bone resorption caused by mechanical stress during tooth movement through inhibition of osteoclast differenciation and function.

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It is important to be able to conduct stereognosis/registration for examination, diagnosis, planning treatment, making clinical records and dental laboratory procedure operations, etc. We therefore investigated the present conditions of students' ability to conduct stereognosis/registration and problems related to the procedure for the purpose of establishing future education guidelines for students.
A total of 103 sixth-year dental students were given photographs of a maxillary metal base denture and were instructed to draw a cross section of each the denture and the oral tissues. The drawings were collected, and evaluated based on 10 items. It was found that there was a relation between evaluation results and problems experienced in practice (i.e., 88 prosthodontics cases).
The results showed a wide variation in student ability. The ability to prepare stereognosis/registration of outside structures was comparatively good, but that done for internal structures and the relationship to oral tissues was insufficient. There was no significant relationship between the ability to conduct stereognosis/registration and problems that were experienced in practice. There results suggest that further training for the subject of stereognosis/registration is required.

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Purpose : Fundamental research was done for ozone ointment, electrolytic acid functional water, strongly electrolytic acid gell, and ozone gell for the purpose of dentistry clinical application as a promotion base of wound healing.
Materials and Methods : We used 16 male 4-week-old Wistar rats, ozone ointment, macrogol ointment, ozone gell, strongly electrolytic acid gell, and electrolytic acid functional water as a material. After inhalation anesthesia, wound sites were respectively prepared at 4 points on the dorsal skin. Various types of gell and functional water were applied, and then the diameters of these wound sites were measured. From the experiment start, it slaughtered four animals at a time respectively 1, 3, 5, and 7 days afterward, and the specimen was produced. The paraffin section specimen performed and microscope observation was carried out.
Results : In the macroscopic observation in the wound therapeutical trial I, reduction of the wound part was promoted in the example of ozone ointment, and the significant difference was especially accepted in the reduction rate between ozone ointment and an object group in the example on the 7th. Histologically, wound healing was achieved in the ozone ointment group.
Moreover, in the wound therapeutical trial II, especially in the example of seven day, there were significant differences between electrolytic acid functional water and ozone gell, between electrolytic acid functional water and ozone ointment, and between strongly electrolytic acid gell and ozone ointment. Also in histological observation in which the significant difference was accepted, the example of ozone ointment was assuming the best view, and subsequently to the order of strongly electrolytic acid gell, ozone gell, and electrolytic acid functional water, it was good.
Conclusion : As for ozone ointment, from histological and macroscopic observation, the good result was obtained as compared with electrolytic acid functional water, strongly electrolytic acid gell, and ozone gell.

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Application of polyelectrolyte complex (PEC) as a biological material is expected because it does not inhibit cell adhesion or proliferation. In this study, we cultured gingival fibroblasts in a PEC-coated culture dish, and investigated the expression pattern of a cell adhesion molecule, integrin, and that of tyrosine-phosphorylation to analyze intracellular signal transmission to biologically evaluate PEC as a functional biological material for the dental field. The following findings were obtained.
1. The integrin expression in cells cultured in PEC-coated dishes was comparable or higher than that in the control group.
2. Integrin and vinculin were present in the cytoplasm of cells cultured in PEC-coated dishes, and their expression patterns were similar to those in the control group.
3. The tyrosine-phosphorylating protein expression in cells cultured in PEC-coated dishes was similar to that in the control group, suggesting that the function of the intracellular signal transmission system was normal in cells cultured on PEC.
The above findings revealed that cell culture in PEC-coated dishes did not inhibit integrin expression or tyrosine phosphorylation in the intracellular signal transmission system.

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[in Japanese]

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[in Japanese]

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