The efficacy of rhBMP-2 loaded hydrogel composite on bone formation around dental implants in mandible bone defects of minipigs

BACKGROUND: In dental or orthopedic surgery, bone substitutes are inserted with implants to promote osteogenesis and enhance osseointegration. The purpose of this research was to evaluate the efficacy of rhBMP-2 (recombinant human bone morphogenetic protein-2) loaded hydrogel composite for bone formation around dental implant in minipig mandible bone defect models. METHODS: We made bone defects with a diameter of 4 mm in minipig mandibles and inserted implants of the same size, to mimic the cases of inserting the screws in the bone defect or poor-quality bone. The rhBMP-2 (300 μg) loaded hydrogel composite (0.5 cc) inserted in the bone defect with the implant in the rhBMP-2 group. After 4 weeks, the mandibles were harvested to evaluate the new bone mass around implants using plain radiographs, micro-CT, and histology. RESULTS: The micro-CT analysis result showed that the quantity of new bone generation around the implant in the rhBMP-2 group was greater than that in the other groups. Comparing the ratios of bone to implant area in three groups by histology, the amount of newly formed bone in the rhBMP-2 group was the most. CONCLUSION: The rhBMP-2 loaded hydrogel composite promotes osteogenesis around dental implant in minipig mandible bone defect, and enhance osseointegration between the dental implant and host bone.