Effects of Platelet-Rich Plasma on the Healing of Autologous Bone Grafted Mandibular Defects in Dogs

Purpose: This study was undertaken to describe both radiographically and with histomorphometric analysis the effect platelet-rich plasma (PRP) has on immediate autologous bone grafts in a dog model.

Methods: Thirteen dogs comprised the study. Twelve adult dogs received bilateral inferior mandibular border defect resections measuring 2 cm x 1 cm. The right defect was immediately grafted with milled autologous iliac corticocancellous bone along with 2 cc of PRP that was developed in a standardized fashion. The left side was immediately grafted with the same amount of autologous iliac corticocancellous bone placed without PRP. Three animals were sacrificed at 1, 2, 3, and 6 months. A thirteenth dog underwent bilateral inferior border resections with only PRP placed in the right defect, and nothing placed in the left defect. This dog was sacrificed at 6 months. Ten and 3 days before sacrifice all animals received 10 mg/kg body weight tetracycline intravenously. At sacrifice, grafts along with adjacent native bone were harvested, fixed, radiographed, and processed for epifluorescence analysis.

Results: Analysis of digitized radiographs indicated that at 1 and 2 months the non-PRP grafts were significantly more dense than the PRP grafts, and at 3 and 6 months there was no significant difference. Histomorphometric analysis showed that at 1 and 2 months there was significantly less grafted bone and more new bone in the PRP grafts than in the non-PRP grafts. At 3 and 6 months there was no difference in the amount of grafted bone or new bone between the PRP and non-PRP grafts. Histology of the control dog showed incomplete bony healing at 6 months, suggesting that this was a critical sized defect. The bone apposition rate for all times in the PRP and non-PRP graft sites did not significantly change.

Conclusion: PRP appeared to enhance early autologous graft healing. However, after 2 months this effect is no longer significant. The early enhanced healing occurred by increasing the amount of non-viable grafted bone that was removed and increasing the amount of new bone that was formed. PRP did not change the rate at which new bone was formed, and no increase in trabecular density was realized in these grafts.