Studies of the Etiology and Therapeutic Approach of Alveolar Bone Resorption

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The following main results were obtained in the present joint study. I. Research Group of Experimental Animal Model of Bone Resorption: 1) During the phase of bone resorption in the bone marrow cavity of rat by an injection of colchicine, osteopontin mRNA expression was observed. 2) Lathyrogenic agents induced a severe resorption of the area of alveolar bone and periodontium in rat. This alveolar bone resorption may be a new model of experimental alveolar bone resorption. II. Research Group of the Function Producing Mechanism in Bone Resorption: 1) The presence of the monouclear osteoclast was ascertained and the three-dimensional structure of locomoting osteoclast was clarified. 2) The lack of bone resorption in op/op mice is due to the inability of the local microenvironment production by osteoblastic cells. In contract, the lack of bone resorption in oc/oc mice is due to a defect in osteoclast progenitors. 3) It was found that osteoclast formation required some unknown factor(s) pro … More duced by stromal cells through PGE_2 and protein A kinase pathway and that the osteoclast formation also required direct adherence of stromal cells to stem cells through some cell adhesion molecules such as ICAM-1 and LFA-1.4) Several kinds of cytokines produced by squamous cell carcinoma are responsible to a marked increase in osteoclastic bone resorption and malignancy associated hypercalcemia. 5) S180A, an animal model of malignancy, produced bone resorbing factors such as TGFalpha and IL-1alpha. III. Research Group of the Prevention and Therapeutic Approach to Alveolar Bone Resorption: 1) The circadian phase of bone resorption is an important factor controlling the magnitude in the effect of blockers of bone resorption. 2) The increased levels of osteocalcin in gingival crevicular fluid may reflect the severity of periodontal tissue breakdown. 3) The bone morphogenetic protein-atelocollagen complex induced the new bone formation in rat. 4) The occluding load of the lower denture during mastication may be an effecting factor on the alveolar bone resorption. 5) Aspirin may have an inhibitory effect on alveolar bone resorption in the mandible with traumatic occlusion. Less