To investigate the role of osteoprotegerin (OPG) in implant osseointegration in ovariectomized rats.

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.

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.

Systemic administration of OPG can improve implant osseointegration and fixation in ovariectomized rats, resulting from the increased peri-implant bone mass and improved trabecular microarchitecture.