The local administration of parathyroid hormone encourages the healing of bone defects in the rat calvaria: Micro-computed tomography, histological and histomorphometric evaluation.

Objective: To evaluate the effect of a single-dose local administration of PTH on bone healing in rat calvarial bone defects by means of micro-computed tomography, histological and histomorphometric analysis.

Design: Critical-size cranial osteotomy defects were created in 42 male rats. The animals were randomly divided into 3 groups. In the C Group, the bone defect was only filled with a blood clot. In the S Group, it was filled with a collagen sponge and covered with bovine cortical membrane. In the PTH Group, the defect was filled with a collagen sponge soaked with PTH and covered with bovine cortical membrane. The groups were further split in two for euthanasia 15 and 60days post-surgery. Data was statistically analyzed with t-tests for independent samples or the nonparametric Mann-Whitney test when applicable. Intragroup comparisons were analyzed with paired t-tests (p<0.05).

Results: Micro-CT analysis results did not demonstrate statistically significant intergroup differences. At 15days post-surgery, the histomorphometric analysis showed that the PTH Group exhibited a significantly higher percentage of bone formation compared with the S Group. At 60days post-surgery, a higher percentage of new bone was observed in the PTH group.

Conclusion: The results suggest that the local administration of PTH encouraged the bone healing in critical-size calvarial defects in rats.