Effectiveness of xenogeneic and synthetic bone‐block substitute materials with/without recombinant human bone morphogenetic protein‐2: A preclinical study using a rabbit calvarium model

Aim To investigate new bone (NB) formation by using bone‐block substitute materials with/without recombinant human bone morphogenetic protein‐2 (rhBMP‐2). Materials and Methods Three synthetic bone‐block substitute materials [biphasic calcium phosphate (BCP); nanostructured hydroxyapatite (NH); 3D‐printed tricalcium phosphate/hydroxyapatite (3DP)] and one xenogeneic deproteinized bovine bone mineral (DBBM) block substitute were affixed to rabbit calvarium using osteosynthesis screws, either with rhBMP‐2 (n = 12) or without rhBMP‐2 (n = 16). At 2 or 12 weeks (n = 6 with rhBMP‐2 and n = 8 without rhBMP‐2 for each week), histologic, histomorphometric and microcomputed tomography analyses were performed. Results The application of rhBMP‐2 increased NB formation in all experimental groups at both weeks. DBBM resulted in a greater area of NB compared with synthetic blocks either with or without rhBMP‐2 at 2 weeks (2.8 ± 0.9 vs. 1.4 ± 0.5–1.9 ± 1.4 mm2; 1.4 ± 1.0 vs. 0.6 ± 0.3–0.9 ± 0.5 mm2) and without rhBMP‐2 at 12 weeks (3.0 ± 0.8 vs. 1.7 ± 0.7–2.6 ± 1.5 mm2) (p > 0.05). NB formation did not differ significantly for DBBM and the three types of synthetic block with rhBMP‐2 at 12 weeks (4.5 ± 2.0 vs. 3.8 ± 0.7–5.1 ± 1.1 mm2; p > 0.05). Conclusions rhBMP‐2 enhanced NB in all blocks. DBBM blocks yielded more NB than synthetic blocks without rhBMP‐2. The application of rhBMP‐2 appears to compensate for differences in late healing.