Effects of intermittent parathyroid hormone on cementoblast‐mediated periodontal repair.

Objectives: To investigate the effects of intermittent parathyroid hormone on cementoblast‐mediated periodontal repair in the context of orthodontic‐induced root resorption. Materials and Methods: The rat model of orthodontic‐induced root resorption was established. Sixty rats were randomly allocated into the experiment group (n = 30) and the control group (n = 30), either receiving a daily subcutaneous injection of recombinant human PTH or placebo vehicle. Enzyme‐linked immunosorbent assay, Micro‐computed tomography, hematoxylin and eosin staining, and immunohistochemistry staining were performed to detect the periodontal repair. In vitro, OCCM‐30 cells were exposed to intermittent PTH (incubated with PTH for the first 6 h in each 24‐h cycle). After three cycles, flow cytometry assay, alkaline phosphatase staining, and Alizarin red staining were performed. Quantitative real‐time polymerase chain reaction and Western blotting were employed to further determine the effects of intermittent PTH. Results: Intermittent PTH‐responsive repair enhancement was detected with the expression of bone sialoprotein, osteocalcin, collagen‐1, and alkaline phosphatase significantly upregulated. Increased expressions of cementoblastic proteins were positively correlated to cycles of PTH administration. The proportion of cementoblasts in S and G2/M phases was increased; namely, intermittent PTH promoted cementoblast cell proliferation. Conclusions: Intermittent parathyroid hormone administration promotes cementoblast‐mediated cementogenesis during periodontal repair in a time‐dependent manner. [ABSTRACT FROM AUTHOR]