| Objectives Retinoic acid-induced osteoporosis model was used to explore the microstructure changes of condyle bone tissue in osteoporotic rats.Established an elevated bite model to explore the expression changes of S100A12 and MMP-13 in the synovial membrane of the temporomandibular joint of osteoporotic rats,and provided theoretical support for the pads on molars of orthodontic patients with clinical osteoporosis.Methods The rats were randomly divided into osteoporosis occlusal pad group(group A),osteoporosis group(group B),normal occlusal pad group(group C)and control group(group D)with 20 rats in each group.Rats in the osteoporosis occlusal pad group and the osteoporosis group were given 85 mg/(kg·d)retinoic acid by gavage for 15 days to establish an osteoporosis model.After the modeling was completed,the femoral bone mineral density was measured by a bone mineral density tester,and the micro-structure changes of the condyle bone were observed by Micro CT.Resin was attached to the maxillary molar and the occlusion was elevated by 1.5 mm in the osteoporosis occlusal pad group and normal occlusal pad group.The rats of each group were sacrificed at 7,14,21 and 28 days.Hematoxylin-Eosin staining was used to observe tissue morphology and immunohistochemistry to detect the changes of S100A12 and MMP-13 in the temporomandibular joint synovium of rats.Results 1 The general situation showed that rats in the osteoporosis group reduced appetite after 5 to 7 days of gavage with retinoic acid.15 days later,body hair was haggard,eye corners hemorrhage,lethargy,and rickets.Rats in the normal group have neat hair,bright color,vibrant,and sensitive response.Using SPSS 26.0 statistical software analysis,it was found that the body weight and femoral bone density of rats in the osteoporosis group were lower than those in the normal group,with statistical differences(P<0.05).The comparison of the microstructural parameters of the condyle bone trabecular structure showed that the bone volume fraction,trabecular bone thickness,trabecular bone number,and bone density of the osteoporosis group were significantly lower than those of the normal group,and the trabecular bone separation was significantly higher than that of the normal group.2 HE results:The synovial lining layer of group A and group C had obvious hyperplasia,inflammatory cell infiltration,and increased capillaries.The synovial lining layer of group B was not hyperplasia,only a few parts had hyperplasia.The lining layer of group D contained 1～2 layers of synovial cells,the subsynovial layer was loosely arranged fibrocytes,and capillaries were occasionally seen.The order of synovial pathology score was group A > group C > group B > group D.A large number of fissures and cartilage thickness increased in the surface fibrous layer of the condyles in groups A and C.Occasionally collagen fibrous fissures were found on the surface of the condyle in group B.The surface of the condyle cartilage in group D was intact and undamaged,the structure was clearly structured and arranged in an orderly manner.From the deep layer to the surface layer,there were cartilage layer,hypertrophic layer,proliferative layer and fibrous surface layer.3 Immunohistochemical staining results: From 7 to 28 days,the positive expression of S100A12 protein in the synovium of group A was getting stronger and stronger.The positive expression of MMP-13 first increased and then decreased,and the maximum value was 21 days.The positive expression of S100A12 and MMP-13 in the synovium of group B was less.The positive expression of S100A12 and MMP-13 in the synovium of group C gradually increased,reached the highest value in 21 days,and then decreased.The positive expression of S100A12 and MMP-13 in the synovium of group D was the least.Conclusions 1 In a rat model of osteoporosis induced by retinoic acid(85mg/kg),the condyle tissue showed osteoporosis.2 The occlusion increased by 1.5 mm,7 to 28 days,inflammation of the temporomandibular joint synovial tissue in the osteoporosis occlusal pad group and the normal occlusal pad group developed gradually,and became the most severe at 21 days,and then relieved.3 S100A12 and MMP-13 were positively expressed in the synovium of the temporomandibular joint in the osteoporotic occlusal pad group and the normal occlusal pad group.The positive expression level of MMP-13 was consistent with the change trend of synovial pathology score,suggesting that MMP-13 could be used as an observation factor to monitor the development of synovial inflammation of temporomandibular joint.Figure 20;Table 8;Reference 111... |
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