Synthetic Parathyroid Hormone May Augment Bone Volume in Autogenous Grafts: A Study in Rats.

Abstract

Synthetic parathyroid hormone [PTH(1-34)] has been investigated for its benefits on bone healing and osteoporosis treatment; however, there is little information regarding bone grafts. This study therefore investigates the effect of PTH(1-34) on autogenous bone graft healing. Bone grafts were harvested from the calvarium of rats with a trephine bur (3-mm internal diameter) and placed on the cortex near the mandible angle with a titanium screw. Animals were randomly assigned to group 1 (control): subcutaneous injections of saline solution, three times a week (n = 15); group 2: 2 μg/kg PTH(1-34), three times a week (n = 15); and group 3: 40 μg/kg PTH(1-34), three times a week (n = 15). Thirty days postoperatively, the animals were killed, and specimens (implant + bed + graft) were removed and used for undecalcified sections. The following histometric parameters were evaluated: total bone thickness (TT) (bed + gap + graft), graft thickness (GT) (adjacent to the implant), bone-to-implant contact (BIC), and bone area (BA) (within the limits of the threads). Five additional animals were sacrificed immediately after surgery (zero hour) to register bed and graft sizes before healing. Group 3 showed significantly greater bone gain compared with groups 1 and 2 (TT and GT, P <0.05). In relation to initial thickness (zero hour), groups 1 and 2 showed a total decrease in volume of 15.91% and 20.83%, respectively, whereas group 3 showed a slight bone gain (1.21%). Data analysis revealed a significant difference for group 3 compared with groups 1 and 2 (P <0.01). No differences were observed for BIC and BA (P >0.05). Systemic administration of PTH(1-34) augmented bone volume in autogenous grafts.