Histological assessment of the effects of teriparatide therapy on mandibular fracture healing: A preclinical study

This study was performed to evaluate the effects of teriparatide therapy on mandibular fracture healing in a rat model. A unilateral mandibular fracture, 5 mm posterior to the last molar tooth, was surgically created in 120 rats. Half of the animals received a daily subcutaneous injection of 2 μg/kg teriparatide while the control rats received normal saline, starting from the day of surgery until sacrifice. Twenty rats from each group were sacrificed on postoperative days 10, 20, and 30. The healing process was evaluated histologically and scored using a grading system (ranging from 1 to 10). On day 10 the fracture gaps of the control and teriparatide groups were mainly filled with fibrous tissue and new trabecular bone, respectively. On day 20 a large amount of new trabecular bone and some areas of fibrocartilaginous tissue were seen in the fracture gaps of the control rats. In the teriparatide group the fracture area was entirely filled with trabecular bone, which in some areas had been replaced by mature bone. On day 30 the fracture gaps of the control group were entirely bridged by new trabecular bone, while in the teriparatide group they was predominantly filled with mature bone. At all three time-points the mean healing scores for the teriparatide group (6.20 ± 0.70, 8.50 ± 0.69, and 9.85 ± 0.37, respectively) were significantly higher (p < 0.001) than for the control group (4.90 ± 0.55, 7.15 ± 0.59, and 8.90 ± 0.64, respectively). Based on the results of this study, teriparatide should be tested in humans in order to establish whether comparable results can be achieved.