Regeneration of rabbit calvarial defects using biphasic calcium phosphate and a strontium hydroxyapatite-containing collagen membrane.

Abstract

Biphasic calcium phosphate (BCP) composed of 10% hydroxyapatite (HA) and 90% beta-tricalcium phosphate has been developed. Recently, a strontium hydroxyapatite-containing collagen membrane (Sr) was shown to stimulate early bone formation in rat calvarial defects at 4weeks postoperatively, as compared with a cross-linked collagen membrane, for guided bone regeneration (GBR). The objective of this study was to evaluate these novel biomaterials for GBR in relation to a non-cross-linked collagen membrane (BG) and deproteinized bovine bone mineral (BO). Twenty New Zealand rabbits were used in this study. Four defects of 7mm in diameter were created in each rabbit, and three of the defects were treated with BG/BO, Sr/BO, and Sr/BCP. Ten rabbits were sacrificed at 12 and 24weeks, respectively. Histological and histomorphometric analyses were conducted. Volumetric densities of mineralized new bone (MNB), bone marrow (BM), residual grafting material (RG), and non-mineralized connective tissue (NCT) were determined for each group. After 12weeks, Sr/BCP yielded more MNB than BG/BO and Sr/BO with no significant difference among the three groups. After 24weeks, however, Sr/BCP demonstrated significantly more MNB than BG/BO and Sr/BO. Both after 12 and 24weeks, Sr/BCP showed significantly less RG than BG/BO and Sr/BO. There was a significant increase in MNB in Sr/BCP from 12 to 24weeks. In defects grafted with BCP, more MNB was formed while less RG remained, than indefects grafted with BO. The Sr membrane was as effective as BG when comparing Sr/BO with BG/BO.