1997 Fiscal Year Final Research Report Summary
Cyto-histological study of root resorption in orthodontic tooth movement
| Project/Area Number |
08672373
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
矯正・小児・社会系歯学
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| Research Institution | THE UNIVERSITY OF TOKUSHIMA |
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Principal Investigator |
SUMITANI Koji THE UNIVERSITY OF TOKUSHIMA,UNIVERSITY DENTAL HOSPITAL,ASSISTANT PROFESSOR, 歯学部・附属病院, 講師 (30206586)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Shintaro THE UNIVERSITY OF TOKUSHIMA,UNIVERSITY DENTAL HOSPITAL,RESEARCH ASSOCIATE, 歯学部・附属病院, 助手 (00274241)
HIURA Kenji THE UNIVERSITY OF TOKUSHIMA,UNIVERSITY DENTAL HOSPITAL,ASSISTANT PROFESSOR, 歯学部・附属病院, 講師 (20228696)
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| Project Period (FY) |
1996 – 1997
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| Keywords | odontoclast (s) / Osteoclast (s) / Bone resorption / root resorption |
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| Research Abstract |
The mechanisms of root resorption in orthodontic movement is not still clear. We investigated the inhibitory effect of various compounds and cells on osteoclasts instead of osteocytes.
Bafilomycin A_1, the vacuolar type H^+ -ATPase inhibitor completely suppressed osteoclastic bone resorption stimulated by parathyroid hormone, but did not affect procathepsin L secretion, while acetazolamide, the carbonic anhydrase II inhibitor, suppressed both bone resorption and the secretion. It is suggested that bone resorption by procathepsin L secretion and its processing are regulated by proton production and secretion.
The suppressive effect of N (benzyloxycarbonyL) -L-phenylalanyl-L-tyrosinal on bone resorption was examined in vitro and in vivo. This synthetic peptidyl aldehyde was found to be a potent and selective cathepsin L inhibitor in our screenig for cysteine protease inhibitors. 1.5 nM of this compound markedly inhibited parathyroid hormone-stimulated osteoclastic bone resorption. In addit
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ion, intraperitoneal administration of this peptidyl aldehyde for 4 weeks suppressed bone weight loss dose dependently in the ovariectomized mouse. Hydroxy-proline measurement of the decalcified femurs from these ovariectomized mice suggested that this compound acts as a bone resorption suppressor through the inhibition of collagen degradation.
In order to investigate the role of osteocytes in bone resorption, we examined the homogenate and conditioned medium from purified chick calvarial osteocytes in a pit-formation assay using unfractionated bone cells from mice. The inhibitory protein, of molecular mass 18.5 kDa, showed significant dose-dependent inhibition of pit formation by unfractionated bone cells from mice and rabbits, and by human giant tunmor cells. Microinjection of the protein into osteoclasts caused disruption of the podosomes in the cells. Thus chick calvarial osteocytes may be involved in the regulation of bone resorption by osteoclasts.
These findings suggest that we have the possibility to control the root resorption caused by odontoclasts in orthodontic tooth movement. Less
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