Sinus augmentation using rhBMP-2/ACS in a mini-pig model: Relative efficacy of autogenous fresh particulate iliac bone grafts

Background: Implant dentistry in the posterior maxilla often requires bone augmentation. The gold standard, autogenous bone graft, requires additional surgery with associated morbidity, while bone biomaterials may not support relevant bone formation. Recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS), however, induces significant, clinically relevant bone formation in several settings including the maxillary sinus floor. Objective: The objective of this study was to compare local bone formation and osseointegration following maxillary sinus augmentation using rhBMP-2/ACS or a particulate autogenous cancellous bone graft obtained from the iliac crest in conjunction with immediate placement of dental implants. Materials and methods: Bilateral sinus augmentation using an extraoral approach including rhBMP-2 (0.43 mg/ml)/ACS or the autogenous bone graft, alternated between left and right sinus cavities in five adult male Yucatan mini-pigs, was performed. Two 12-mm dental implants were inserted into the sinus wall protruding approximately 8 mm into the sinus cavity. Surgical sites were closed and sutured in layers; block biopsies collected for histometric analysis at 8 weeks. Results: rhBMP-2/ACS induced bone of significantly greater and consistent quality compared with the iliac crest autogenous bone graft; bone density averaging 51.9 ± 3.0% vs. 32.9 ± 2.5% (P = 0.01). However, there were only numerical differences in augmented bone height (9.3 ± 0.5 vs. 8.6 ± 0.7 mm) and bone-implant contact (37.4 ± 3.0% vs. 30.7 ± 5.9%) between treatments. Conclusion: rhBMP-2/ACS induces bone of superior quality compared with an iliac crest particulate autogenous cancellous bone graft when used for maxillary sinus augmentation, and should perhaps be considered the new standard for this indication.