Study On The Effect Of Curculigoside On Bone Reconstruction During Orthodontic Tooth Movement In Osteoporosis

Osteoporosis（OP）is a systemic skeletal disease characterized by a decrease in bone density and destruction of the microstructure of bone tissue,ultimately leading to increased bone fragility and susceptibility to fracture.Orthodontic tooth movement is based on the modification of periodontal tissues,and the loss of alveolar bone caused by periodontitis as an inflammatory infectious disease can adversely affect orthodontic treatment.orthodontic tooth movement based on periodontal tissue may also be affected by the osteoporotic state.Nowadays,more and more people in China are seeking orthodontic treatment for functional and aesthetic reasons,including patients with osteoporosis,such as women in menopause and adolescents with idiopathic osteoporosis,etc.Rebuilding the balance of bone reconstruction during tooth movement in such orthodontic patients with osteoporosis is the key to successful orthodontic treatment.The role of drugs for osteoporosis is mainly to inhibit bone resorption,promote bone formation or both.If the relevant therapeutic drugs can effectively control the rate of orthodontic tooth movement while reestablishing the balance of bone reconstruction in patients with osteoporosis,this has positive clinical significance for orthodontic treatment.In this study,we used Curculigoside（CCG）as an experimental drug to investigate the therapeutic effects of CCG on the osteogenic differentiation of MC3T3-E1 cell line under static tension and on bone reconstruction in an orthodontic tooth movement model of osteoporotic rats by simulating in vivo and in vitro conditions of the orthodontic process,and to provide new ideas for clinical orthodontic treatment.In an in vitro experiment,we examined the survival rate of MC3T3-E1 cells treated with different concentrations of H₂O₂ by CCK8 method to determine the optimal modeling concentration for oxidative stress injury,and the results showed that 200μmol/L had a good inhibitory effect on the cells.The protective effect of CCG on MC3T3-E1 cells under oxidative stress was then investigated,and the results showed that the cell survival rate was significantly lower after H₂O₂ treatment compared with the control group,and increased after different concentrations of CCG treatment.Next,we investigated the osteogenic effect of CCG by treating MC3T3-E1 cells with CCG for 7 d and performing alkaline phosphatase（ALP）staining and ALP quantification,and the results showed that certain concentrations of CCG could promote osteogenic differentiation of MC3T3-E1 cells.Finally,we applied static tension to MC3T3-E1 cells by a four-point bending force device to simulate in vivo orthodontic tooth movement in which the alveolar bone was pulled by the periodontal membrane fibers,and found that static tension in the physiological state promoted osteogenic differentiation of MC3T3-E1 cells and partially reversed the inhibitory effect of oxidative stress on osteogenic differentiation of MC3T3-E1 cells.In the in vivo experiments,a glucocorticoid osteoporosis model was established in rats,and the treatment was administered by means of modeling at the same time.The rats were grouped based on the successful establishment of the osteoporosis model,and a tensile force of approximately 0.49 N was applied intraorally to the maxillary first molar to observe the effect of osteoporosis on orthodontic tooth movement.After2 weeks of tooth movement,the rats were euthanized.The bone density of the femur of the rats was examined by X-ray,the organ toxicity of CCG to the rats was observed by histological section,the ALP level was examined by serological examination,and the distance of orthodontic tooth movement in the maxilla and the bone parameters related to the alveolar bone at the root bifurcation of the maxillary first molar were examined by Micro-CT.The results showed that the femoral bone density decreased and the serum ALP level decreased in the osteoporosis model group;the femoral bone density increased and the serum ALP level increased in the CCG effect group.In the orthodontic tooth movement distance,the first molar movement distance of the rats in the osteoporotic group increased compared with that in the orthodontic force group alone.micro-CT results showed that the alveolar bone density at the root bifurcation of the maxillary first molar in the rats that underwent orthodontic force increased compared with that in the control group,and this effect was attenuated by the osteoporotic state,while the corresponding bone parameters in the CCG treatment group increased.The above indicates that CCG has a certain degree of therapeutic effect on osteoporotic rats and can promote their osteogenesis,while osteoporosis may affect the balance of bone reconstruction during orthodontic tooth movement in rats,resulting in lower alveolar bone mass.In conclusion,CCG can promote osteogenic differentiation of MC3T3-E1 cells and has a protective effect against oxidative stress injury,has a certain therapeutic effect on glucocorticoid osteoporotic rats,and can restore the balance of bone reconstruction during orthodontic tooth movement in osteoporotic state to a certain extent.