Abstract:

Objective    To investigate the influence of ibandronate on orthodontic tooth resorption in rats through observing the histological changes, cementoclasts in periodontal tissues and the expression of osteoclast differentiation factor (ODF). Methods   A total of 48 SPF female Wistar rats were chosen in this study, and the rat model for orthodontic tooth movement was established. 50μL ibandronate solution was injected into the sub-periosteum area adjacent to the left upper first molar (the experimental side) every  3  days during the experiment, and the right maxillary first molar was served as a control (the control side) with an injection of 50μL 0.9% NaCl solution into the corresponding area at the same time intervals. The administration of ibandronate solution was started 3 days before the setting of appliances. After orthodontic force was applied for 3, 7 and 14 days, the rats were killed in batches (16 animals in each period). 8 rats were chosen for histology observation of periodontal tissues, and the remaining 8 were used for scanning electron microscopy (SEM) observation of root resorption. Results   ① On days 7 and 14, the number of cementoclasts in the experimental side was significantly less than in the control side(P＜0.05). ② The expression of ODF on the pressure side of periodontium on experimental upper first molar was significantly lower than that on the control side on days 7 and 14(P＜0.05). ③ The SEM results showed that on days 3, 7 and 14, there were fewer and smaller resorptionlacunae in the experimental side than in the control side. Conclusion   This study demonstrateed that local administration of ibandronate can reduce the number of osteoclasts in the pressure side of periodontal tissues, lower the expression of ODF, and inhibit orthodontic root resorption.

Key words: Ibandronate; Cementoclasts; Root resorption; Osteoclast differentiation factor; Scanning electron microscopy