Vertical bone augmentation using collagenated or non-collagenated bone substitute materials with or without recombinant human bone morphogenetic protein-2 in a rabbit calvarial model

Purpose The aim of this study was to determine 1) the bone-regenerative effect of porcine bone block materials with or without collagen matrix incorporation, 2) the effect of a collagen barrier, and 3) the effect of adding recombinant human bone morphogenetic protein-2 (rhBMP-2) to the experimental groups. Methods Four treatment modalities were applied to rabbit calvaria: 1) deproteinized bovine bone mineral blocks (DBBM), 2) porcine bone blocks with collagen matrix incorporation (PBC), 3) porcine bone blocks alone without collagen matrix incorporation (PB), and 4) PBC blocks covered by a collagen membrane (PBC+M). The experiments were repeated with the addition of rhBMP-2. The animals were sacrificed after either 2 or 12 weeks of healing. Micro-computed tomography (micro-CT), histologic, and histomorphometric analyses were performed. Results Micro-CT indicated adequate volume stability in all block materials. Histologically, the addition of rhBMP-2 increased the amount of newly formed bone (NB) in all the blocks. At 2 weeks, minimal differences were noted among the NB of groups with or without rhBMP-2. At 12 weeks, the PBC+M group with rhBMP-2 presented the greatest NB (P<0.05 vs. the DBBM group with rhBMP-2), and the PBC and PB groups had greater NB than the DBBM group (P>0.05 without rhBMP-2, P<0.05 with rhBMP-2). Conclusions The addition of rhBMP-2 enhanced NB formation in vertical augmentation using bone blocks, and a collagen barrier may augment the effect of rhBMP-2.