| Co-Investigator(Kenkyū-buntansha) |
SHIBATA Tatsuya Tsurumi University, School of Dental Medicine, Instructor, 歯学部, 助手 (90323708)
SHIMADA Akemi Tsurumi University, School of Dental Medicine, Instructor, 歯学部, 助手 (00339813)
OIDA Shinichiro Tsurumi University, School of Dental Medicine, Associate Professor, 歯学部, 助教授 (10114745)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
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| Research Abstract |
One of the problems in tooth replantation is occurrence of root resorption and ankylosis. We examined if bisphosphonates, which inhibit bone resorption and ectopic calcification, inhibit root resorption and ankylosis using the rat molar replantation model. Extracted molars were placed in 1 mM alendronate (ALN) or saline (SAL), and replanted into their sockets. Resorption of roots and alveolar bones and ankylosis were significantly reduced at 14 and 21 days in the ALN group compared to the SAL group. The mechanical strength of the periodontal ligament (PDL) in the ALN group was restored to 67% of that of normal teeth at 21 days. Further, we found that the inhibitory effects of alendronate were retained on resorption of roots and bone, but not on ankylosis, in the ALN group at 60 and 120 days. These findings suggest a possible clinical application of local treatment with alendronate prior to tooth replantation.
We also examined if platelet-derived growth factor (PDGF), which accelerates p
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roliferation of PDL cells, inhibits ankylosis of replanted teeth. Extracted molars were placed in PBS (PBS), a collagen carrier in PBS (AC), or PDGF-BB (5 μg/50 μl ; PDGF), and replanted. At 14 and 21 days, ankylosis was frequently seen in the PBS and AC groups, but not in the PDGF group. The PDL of the PDGF group was thick and had functionally oriented collagen fibers between roots and bone, leading to the better restoration of the mechanical strength of the PDL being 53% of that of normal teeth at 21days. To investigate the mechanisms underlying this stimulatory effect of PDGF on the repair of injured PDL after replantation, we examined localization of PDGF receptors and cell proliferation. At 1 day, the PDGF-β receptors were strongly expressed in the cell processes in injured PDL of the PDGF group ; more BrdU labeled cells in the apical and furcation PDL, and bone marrow were seen in the PDGF group compared to the PBS and AC groups. At 3 and 7 days, the expression of PDGF-β receptor and the BrdU labeled cells markedly reduced. The efficacy of topical PDGF may be partly due to stimulation of cell proliferation through PDGF receptors in the initial stage of wound healing process. Less
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