An experimental study on histopathological changes of alveolar bone around hydroxyapatite during orthodontic tooth movement.

Research Project

Project/Area Number	62570858
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Conservative dentistry
Research Institution	Kyushu University
Principal Investigator	HARA Yoshitaka (1988) Kyushu University, Faculty of Dentistry Hospital, Assistant Professor, 歯学部付属病院, 講師 (60159100) 古川猛士 (1987) 九州大学, 歯学部附属病院, 助手 (30128087)
Co-Investigator(Kenkyū-buntansha)	原宜興九州大学, 歯学部附属病院, 講師 (60159100)
Project Period (FY)	1987 – 1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1987: ¥1,600,000 (Direct Cost: ¥1,600,000)
Keywords	Hydroxyapatite / Minor tooth movement / Histopathological study / 骨吸収 / 歯周組織 / 歯槽骨 / 矯正的歯牙移動
Research Abstract	It the been unclear whether M.T.M. is acceptable in the cases treated with bone graft using hydroxyapatite(HAP), which is not bio-degradable. So we examined histological changes of bone among HAP during orthodontic tooth movement. HAP was implanted into artificial bone defects adjacent to second premolars in beagie dogs, and as control no materials was implanted into them. Three months after implantation, the second premolars were moved with orthodontic force. Then they were observed histopathologically. The results obtained were as follows. Amount of movements of the teeth in implanted sites were smaller than control. At pressure zone : Resorptions of bone by osteoclasts were observed both in implanted and control sites, in addition, root resorptions occured adjacently to HAP. Further mutinucleated giant cells closely attached to HAP surrounded by bone and connective tissue. In retention period there was ankylosis between roots and bone around HAP. At tension zone : additional bone from HAP was observed. Bone defects were filled with bone in implanted sites, on the other hand, with connective tissue in control. These results suggested that bone among HAP was resolved by osteoclasts. Clinically, HAP implantation for pressure zone should be avoided because of the occurence of root resorption and ankylosis. But for tension zone it seems to be effective because HAP implantation produces more repaired bone.