1998 Fiscal Year Final Research Report Summary
A study on the morphological changes of osteocytes in rat alveolar bone during orthodontic tooth movement
| Project/Area Number |
08672356
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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 | TOHOKU UNIVERSITY |
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Principal Investigator |
IGARASHI Kaoru Tohoku University, School of Dentistry, Instructor, 歯学部, 助手 (70202851)
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| Co-Investigator(Kenkyū-buntansha) |
SAEKI Shuichi Tohoku University, Dental Hospital, Instructor, 歯学部・附属病院, 助手 (60271954)
SASANO Yasuyuki Tohoku University, School of Dentistry, Instructor, 歯学部, 助手 (30196191)
MIZOGUCHI Itaru Health Sciences University of Hokkaido, Faculty of Dentistry, Professor, 歯学部, 教授 (20200032)
MITANI Hideo Tohoku University, School of Dentistry, Professor, 歯学部, 教授 (50014220)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Osteocyte / Alveolar Bone / Tooth Movement / Intercellular Network |
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| Research Abstract |
The purposes of the present study were 1) to examine the morphological changes of osteocytes in rat alveolar bone during orthodontic tooth movement using immunohistochemistry for actin filaments and 2) to determine a molecular marker for osteocyte metabolism. Eight-week-old male Wistar rats were used in this study. The maxillary first molars were moved buccally by using a expansive spring of Ni-Ti wire with a nominal size of 0.012 inch as described by Igarashi et al. (1998). The animals were killed after 3, 6, 12, 24 hours, 2, 4, 7, 10 and 14 days of tooth movement. After experiments, the animals were fixed with 4 % paraformaldehyde plus 0.5 % glutaraldehyde in 0.1 M PB, pH 7.4, decalcified with 10 % EDTA solution and processed into paraffin embedding. Six-mu in-thick sections were stained with hematoxilin-eosin or antibodies for osteocalcin, typesI,II and X collagen and actin filaments. The results were as follows ;
1) Precursor and mature osteocalcin was a proper molecular marker for examining the metabolic changes of alveolar bone and bone-forming cells.
2) After 3 hours of orthodontic tooth movement, hyaline tissue appeared in the pressure side of the periodontal tissue of all five roots of the first molar. The hyaline tissue spread and almost dessapered at day 10.
3) Immunohistochemistry for actin filament showed intense staining in cytoplasm and cellular processes of osteocytes in control group. Especially young osteocytes showed intense staining. In contrast, the staining of osteocyte cytoplasm adjacent to the hyaline tissue became weak at day 1 and the staining of its cellular processes disappeared at day 4.
These results demonstrated that osteocytes adjacent to the hyaline degeneration tissue became cell death during early stage of orthodontic tooth movement due to the disappearance of intercellular communication between the periodontal tissue cells.
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