2002 Fiscal Year Final Research Report Summary
Development and Histopathologic Features of Odontoclastic Resorption on the Internal Dentin Wall after Replantation of Rat Molars
| Project/Area Number |
12671866
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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 |
Conservative dentistry
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| Research Institution | The Nippon Dental University |
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Principal Investigator |
SHIMAZU Yoshihito The Nippon Dental University, School of Dentistry at Tokyo, Department of Pathology, Assistant Professor, 歯学部, 助手 (10297947)
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| Co-Investigator(Kenkyū-buntansha) |
KITAMURA Kazuo The Nippon Dental University, School of Dentistry at Tokyo, Department of Pathology, Lecturer, 歯学部, 講師 (00224965)
YAGISHITA Hisao The Nippon Dental University, School of Dentistry at Tokyo, Department of Pathology, Lecturer, 歯学部, 講師 (50256989)
TAYA Yuji The Nippon Dental University, School of Dentistry at Tokyo, Department of Pathology, Lecturer, 歯学部, 講師 (30197587)
AOBA Takaaki The Nippon Dental University, School of Dentistry at Tokyo, Department of Pathology, Professor, 歯学部, 教授 (30028807)
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| Project Period (FY) |
2000 – 2002
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| Keywords | rat molars / osmotic pump / odontoclast / osteoclast / growth factor / bisphosphonate / cell adhesion / extracellular matrix |
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| Research Abstract |
The etiology, pathogenesis and prognosis of internal root resorption in human dentition remain to be better understood. We aimed at establishing rat molar model combining an osmotic pump for local-infusion of chemical agents into the periapical region of the mesial root of upper first molars. Male Sprague-Dawley rats (6-wk-old, 200g b.w.) were used. At the surgical operation under general anesthesia, the apical end of the medial root was removed with the aid of a small dental bar (apicoectomy), leaving a drilled hole (around 0.8mm in diameter) through cortical bone. The pump loading 200 μL of an agent-solubilized solution (or vehicle only as control) was implanted subcutaneously on the dosal area and the cannula was placed into the drilled bony hole in the molar region (local-infusion). The results obtained during the funding period prove that rat molar model is useful for investigation of internal dentin resorption. Histologic examination of the replanted molars showed the occurrence
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of resorption lacunae accompanying TRAP-positive multinuclear cells on the internal dentin wall around day 7 after tooth replantation. Resorption lacunae were classified into A and B types, which appeared to correspond to surface and inflammatory types of external root resorption, respectively. The essential event responsible for the development of internal dentin resorption is the replacement of the innate pulp tissue with the ingrowth of granulation tissue and the assembly of a new cell population comprising macrophages and fibroblastic stromal cells. The initial attachment of odontoclasts to the predentin wall does not necessarily need preconditioning with OPN and appears to be mediated by alternative recognition mechanisms. The overal results support the hypothesis that the innate pulp of rat molars possesses in potency inhibitory functions against undesirable resorption activities, but after impairment of the innate pulp environment after tooth replantation, a new paradigm of cell-matrices and cell-cell interactions may act cooperatively to induce clastic acitivities on the internal predintin/dentin wall. Less
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Research Products
(12 results)
