BMP9 promotes peri-implant osseointegration in beagle defects

To evaluate the in vivo efficacy of bone morphogenetic protein 9 (BMP9) relative to bone morphogenetic protein 2 (BMP2) in a beagle peri-implant critical-size defect model.

Peri-implant defects were created in beagle dogs and treated with either a collagen sponge (CS) or deproteinized bovine bone mineral with collagen (OCS-B Xenomatrix collagen [OCS-BC]), with or without BMP2 or BMP9. After 8 weeks, bone regeneration and osseointegration were evaluated using radiographic, histological, and biomechanical analyses.

Radiographic analysis demonstrated that BMP treatment significantly increased peri-implant mineralization, with bone mineral density increasing from 0.597±0.151 (control) to 0.896±0.173 in the CS+BMP9 group (P<0.0001). Histological and histomorphometric analyses corroborated these findings, showing greater new bone formation and higher bone-to-implant contact (BIC) (7.943±7.048 vs. 68.90±20.27 in the CS+BMP9 group; P<0.05) without overt inflammatory reactions. Region-of-interest (ROI)-based micro-computed tomography analysis (200 μm) and resonance frequency analysis further supported improved osseointegration and stability, with osseointegration increasing from 20.32±6.976 to 70.37±0.785 in the CS+BMP9 group (P<0.0001) and the implant stability quotient (ISQ) peaking at 70.92±3.523 in the OCS-BC+BMP9 group (P<0.0001). Two-way analysis of variance indicated scaffold-dependent magnitudes for bulk endpoints, whereas interaction terms were not significant for BIC, ROI-based osseointegration, or ISQ, supporting preservation of BMP9-associated benefits across scaffold types for these outcomes.

BMP9 produced overall improvements comparable to BMP2 and may provide more reproducible osseointegration-related outcomes across scaffold types.