Effects of intermittent administration of parathyroid hormone on bone augmentation in rat calvarium

Objectives: This study examined the effects of parathyroid hormone (PTH) on bone augmentation beyond the skeletal envelope within a plastic cap in rat calvaria. Materials and Methods: The calvaria of 30 rats were exposed, and 2 plastic caps were placed on each. Each of the 10 rats was treated with 35 or 105 g/kg (PTH-35, PTH-105) PTH 3 times per week. The control group was injected with sterile saline 3 times per week. Micro-computed tomography (CT) imaging was performed every 2 weeks for 12 weeks. Micro-CT and histological sections were used to determine the amount of bone augmentation within the plastic caps. Bone volume (BV) was calculated using BV-measuring software. Results: The histomorphometric and histological analyses showed that the amount of bone augmentation was increased significantly in the PTH groups compared with the controls at 12 weeks. The PTH-105 group showed significantly more bone augmentation and osteoblasts compared with the PTH-35 group. Conclusions: These results indicate that the higher the dose of intermittent PTH administered, the greater the amount of bone formation beyond the skeletal envelop in the rat calvarium.