RhBMP-2/alphaBSM induces significant vertical alveolar ridge augmentation and dental implant osseointegration

BACKGROUND: Recombinant human bone morphogenetic protein 2 (rhBMP-2) in a carrier has been shown to induce significant bone formation. Several candidate carriers, however, lack structural integrity to offset compressive forces that may compromise rhBMP-2 bone induction, in particular, for challenging onlay indications such as alveolar ridge augmentation. PURPOSE: The objective of this study was to evaluate rhBMP-2 in a calcium-phosphate cement carrier, alphaBSM, for vertical alveolar ridge augmentation and immediate dental implant osseointegration. MATERIALS AND METHODS: Six adult Hound Labrador mongrels with 5 mm critical size supra-alveolar peri-implant defects were used. Three animals received rhBMP-2/alphaBSM (rhBMP-2 at 0.40 and 0.75 mg/mL) in contralateral jaw quadrants (total implant volume/defect approximately 1.5 mL). Three animals received alphaBSM without rhBMP-2 (control group). The animals were euthanized at 16 weeks post surgery, and block biopsies were processed for histologic and histometric analysis. RESULTS: rhBMP-2/alphaBSM induced substantial augmentation of the alveolar ridge. Control sites exhibited limited new bone formation. Vertical bone augmentation averaged (+/- SD) 4.9 +/- 1.0 mm (rhBMP-2 at 0.40 mg/mL), 5.3 +/- 0.3 mm (rhBMP-2 at 0.75 mg/mL), and 0.4 +/- 0.4 mm (control); new bone area 8.5 +/- 4.2 mm2, 9.0 +/- 1.9 mm2, and 0.5 +/- 0.4 mm2; new bone density 55.1 +/- 6.4%, 61.1 +/- 6.0%, and 67.7 +/- 9.5%; and new bone-implant contact 26.9 +/- 17.5%, 28.5 +/- 1.4%, and 24.6 +/- 16.1%, respectively. Residual alphaBSM comprised < 1% of the new bone. Bone density for the contiguous resident bone ranged from 65 to 71%, and bone-implant contact ranged from 49 to 64%. CONCLUSIONS: Surgical implantation of rhBMP-2/alphaBSM appears an effective protocol for vertical alveolar ridge augmentation procedures and immediate dental implant osseointegration and for onlay indications of lesser complexity.