Effects of osteoprotegerin on implant osseointegration in ovariectomized rats

Objective To investigate the role of osteoprotegerin (OPG) in implant osseointegration in ovariecto⁃ mized rats. Methods 12 weeks after bilateral ovariectomy, each rat accepted 2 titanium screws in the proximal tibiae. All animals were then randomly divided into 2 groups: control (10 rats) and OPG group (10 rats). Subcutaneous injection of OPG (10 mg/kg) or vehicle was performed 3 times a week. 8 weeks later, tibiae with screws were harvested for μCT, histological and biomechanical analysis. Results Compared to control, OPG increased the percent bone volume by 124%, the percent osseointegration by 167%, the mean trabecular number by 111%, the mean trabecular thickness by 92%, the mean connective density by 95%; and decreased the mean trabecular separation by 64% in μCT analysis. OPG also increased bone area density by 160% and bone⁃to⁃implant contact by 234% in histomorphometric evaluation, and increased the maximal push ⁃ out force by 228% in biomechanical test. Conclusion Systemic administration of OPG can