Sinus grafting with autogenous platelet-rich plasma and bovine hydroxyapatite. A histomorphometric study in minipigs.

In this study, bovine hydroxyapatite (HA) alone or in combination with activated platelet-rich plasma (PRP) was examined for its usefulness for single-stage sinus grafting in minipigs. In 12 adult minipigs, Schneider's membrane of 24 sinuses was elevated bilaterally through an extra-oral approach. The material was divided into two groups of 12 sinuses. In one of these groups, the space between Schneider's membrane and the sinus wall was grafted with activated autogenous PRP and HA (PRP side). In the other, HA alone was used for grafting (control side). At the same time two dental implants with a machined surface were inserted into the grafting material through the facial sinus wall. Four animals of each group were sacrificed at 3, 6 and 12 weeks, and undecalcified thin-cut and ground sections (Donath 1988) stained with toluidine blue were prepared. In the facial sinus wall, fewer bone-to-implant contacts were present on the PRP side at 3 and 6 weeks than on the control side. At 12 weeks, the PRP side had caught up with the control side. In grafted bone, contacts on the PRP side were more extensive than on the control side at 3 weeks, had dropped below control side levels at 6 weeks and surpassed these at 12 weeks. This study showed that PRP has a differential effect on osseointegration in grafted bone and local host bone. Combined with HA it was not demonstrably superior to HA alone.