Effects of Ovariectomy on Bone Mineral Density and Integrin Expression in Maxilla of Rats / 대한해부학회지

In postmenopausal osteoporosis, estrogen deficiency leads to unbalance of bone metabolism, decreased bone formation and increased bone resorption, and the result is reduced bone mineral density (BMD) and bone stiffness. The processes of bone formation and resorption involves the expression of integrins in anchoragedependent cells, such as osteoblast and osteoclast. The osteoporosis-induced rats frequently demonstrated the loss of trabecular bone volume in the tibia, vertebra and mandible due to estrogen depletion. However, in maxilla, study has been rare because of its anatomical limits. So the objective of this study was to investigate bony change and property of integrin expression in maxilla of osteoporosis-induced rats. 12-week-old female Sprague-Dawley rats were bilaterally ovariectomized (OVX). At 1, 2, 3, 4, 8 and 12 weeks, control and OVX group rats were sacrificed respectively. BMD of maxilla of the rats was measured using dual-energy X-ray absorptiometry (DEXA). And then the histopathologic observation, histomorphometric analysis and immunohistochemistry with CD44, alpha2 integrin, alpha5 integrin, alpha6 integrin, alphav integrin and beta3 integrin were done. BMD of alveolar bone in maxilla was decreased with significance statistically after OVX 4 weeks and was decreased 18.15% at OVX 12 weeks group compared to control group. From OVX 4 to 12 weeks, the thickness of periodontal ligament space was decreased, the number of osteoclast and the size of marrow stroma were increased than control group. By histomorphometric analysis, the size of marrow stroma of alveolar bone in maxilla was increased 86.42% at OVX 12 weeks group compared to control group. CD44 was widely expressed throughout the odontoblast, cementoblast, dental pulp, preiodontal ligament, osteocyte, osteoclast and perivascular tissue at control group, and CD44 immunoreactivity was increased the odontoblast, osteoblast and osteoclast at OVX groups. alpha2 integrin was expressed the odontoblast and osteoblast at control group, but alpha2 integrin immunoreactivity was decreased the osteoblast at OVX 12 weeks group. alpha5 integrin was expressed the cementoblast, osteoblast and osteoclast at control group, and alpha5 integrin immunoreactivity was decreased the osteoblast and was increased the osteoclast from OVX 4 weeks group. alpha6 integrin was weakly expressed the odontoblast, cementoblast, osteoblast and osteoclast at control group, and alpha6 integrin immunoreactivity was weakly increased the osteoclast from OVX 4 weeks. alphav integrin was expressed the odontoblast and osteoclast at control group, and alphav integrin immunoreactivity was strongly increased the osteoclast from OVX 4 weeks. beta3 integrin was expressed the osteocyte and osteoclast at control group, and beta3 integrin immunoreactivity was strongly increased the osteoclast from OVX 4 weeks. From these results, alveolar bone in maxilla of OVX rats was decreased BMD gradually. Moreover, alpha2 and alpha5 integrin expression of osteoblast was decreased, and alpha5, alphav and beta3 integrin expression of osteoclast was increased in OVX rats. Thus, this study indicates that consideration of reduced BMD is necessary in dental procedure of postmenopausal women.

The Accuracy of Computerized Prediction of the Soft Tissue Profile after Surgical Correction of Mandibular Prognathism

The purpose of this study was to compare the soft tissue movements in facial profile predicted by a computer package with those that had actually accured following a sagittal split ramal osteotomy. The reliability of predicting the results of orthodontic surgical treatment was analysed. The study was based on the serial records of 30 consecutive patients who had been treated by means of a sagittal split ramal osteotomy. The serial lateral cephalometric radiographs used for the study were taken at the following stages: immediate preoperative : immediate postoperative : 6 months postoperative. A superimposition T1, T2-3 was generated to allow visual comparision. The results can be considered in relation to four important parts of the facial profile :the nose, upper lip, lower lip, and chin. The nose & Upper lip:The amount of movement of the upper lipwas not badly predicted for the average case. The lower lip: There was a significant trend over the whole sample for vertical positionof the lower lip to be less well predicted. The chin: The soft tissue movements of the chin were well predicted.