Efficient bone formation in a swine socket lift model using Escherichia coli-derived recombinant human bone morphogenetic protein-2 adsorbed in β-tricalcium phosphate.

Several preclinical studies have shown that Escherichia coli-derived bone morphogenetic protein-2 (E-BMP-2) is as effective as mammalian cell-derived bone morphogenetic protein-2 (C-BMP-2) in the treatment of bone defects. However, further investigation of the effectiveness and determination of the optimal dosage of E-BMP-2 in large animals are still necessary before its full application in humans. This study investigated the efficiency of different concentrations of E-BMP-2 adsorbed in β-TCP for bone augmentation and osseointegration of immediate dental implants in a swine socket lift model. Following exposure of the maxillary sinus lateral wall, a 3.4-mm (diameter) cavity was drilled and filled with 0.1 g of β-TCP containing different doses of E-BMP-2 (0, 10, 30, or 100 μg/site) to lift the Schneiderian membrane. A dental implant was then immediately inserted. Bone-to-implant contact (BIC) and bone density (BD) examined via histological analysis were used as parameters to assess E-BMP-2 efficiency in bone formation. The implant stability quotient (ISQ) was measured using Osstell to determine the effect of E-BMP-2/β-TCP on implant stability. After 8 weeks, the groups that received 30 and 100 μg of E-BMP-2 showed substantial new bone formation in the elevated space, while no bone formation was observed with β-TCP alone. Accordingly, BIC and BD presented a dose-dependent response to increasing doses of E-BMP-2. However, there was no increase in implant stability with E-BMP-2 treatment. In conclusion, the E-BMP-2/β-TCP combination was efficient in bone formation and osseointegration of dental implants in a socket lift model in mini-pigs.