Effects of platelet-rich plasma on bone healing in combination with autogenous bone and bone substitutes in critical-size defects - An animal experiment

Objectives: An animal study was carried out to investigate the influence of platelet-rich plasma (PRP) on the regeneration of bony defects. Material and methods: Critical-size defects in the forehead region of a mini-pig were filled with randomly distributed combinations of autogenous bone, tricalcium-phosphate granules (CeraSorb(TM)), bovine spongious blocks (BioOss(TM)) and a bovine bone inducing collagenous sponge (Colloss(TM)) with and without PRP in two preparations (Cusasan, 3i). The animals were killed after 2, 4 and 12 weeks. The specimens were evaluated microradiographically and immunohistologically. Results: Autologous bone (38+/-9.9%) and Colloss (52.6+/-4.0%) showed the highest remineralization rates at 2 weeks. The initial high expression of BMP-2 in the Colloss(R)-group gives evidence of an early initiation of bony regeneration. At 2 weeks PRP ad modum 3i was able to enhance bone healing significantly (P=0.028) only when applied in combination with autogenous bone (62.8+/-1.6%). Four weeks after surgery, both PRP preparations did no longer increase bony regeneration in the autogenous groups. The osteoconductive effect of Bio-Oss(TM) (38.7+/-5.5%) and CeraSorb(TM) (41+/-4.9%) was remarkable as well 4 weeks after surgery. Nevertheless, the addition of PRP hardly influenced bony regeneration, ceramic degradation or cytokine expression when bone substitutes were applied. At 12 weeks, the level of reossification had adjusted similarly in all groups. Conclusion: PRP did not add additional benefit when xenogenic bone substitutes were used. However, a significant effect on bone regeneration was found in the autogenous group initially when PRP is added.