利塞膦酸钠对正畸大鼠牙根吸收及龈下菌群的影响OA

Objective To investigate the effects and mechanisms of risedronate sodium(RS)on orthodontically induced in-flammatory root resorption and the subgingival microbiota in rats.Methods Fifty Wistar rats were randomly divided into a nor-mal control(Con)group,a model group,a low-dose RS group,a medium-dose RS group,and a high-dose RS group,with 10 rats in each group.Except for the Con group,orthodontic tooth movement models were established in all other groups,and correspon-ding doses of RS were administered for 21 days.After the intervention,periodontal clinical indicators were measured.Hematoxylin and eosin staining and tartrate-resistant acid phosphatase staining were used to observe tissue morphology and count osteoclasts.Enzyme-linked immunosorbent assay was employed to detect the levels of inflammatory cytokines interleukin-6,interleukin-1β,and tumor necrosis factor-α in periodontal tissues.Bacterial culture combined with 16S rRNA gene sequencing was utilized to ana-lyze the composition of the subgingival microbiota.Western blot was used to measure the expression of receptor activator of nuclear factor-KB ligand(RANKL),osteoprotegerin(OPG),and key proteins related to the extracellular signal-regulated kinase(ERK)/mitogen-activated protein kinase(MAPK)signaling pathway in periodontal tissues.Results Compared with the Con group,the periodontal tissues of rats in the model group showed pathological changes such as disorganized cell arrangement and inflammatory cell infiltration.Moreover,the levels of inflammatory cytokines,total bacterial count,counts of multiple pathogenic bacteria,number of multinucleated osteoclasts,RANKL expression,RANKL/OPG ratio,and protein expression levels of p-ERK and p-p38 MAPK were significantly increased in the model group,while the number of Gram-positive cocci significantly decreased(F=67.416-503.922,P＜0.05).After RS intervention,the above abnormal indicators were improved in a dose-dependent manner(P＜0.05).Conclusion RS may alleviate orthodontically induced inflammatory root resorption by inhibiting the activation of the ERK/MAPK signaling pathway,reducing periodontal inflammatory responses,regulating subgingival microbial dysbiosis,and a-meliorating bone metabolism imbalance.