The systemic effect of prolonged use of sodium alendronate on the peri-implant bone repair process.

Background: Bisphosphonates are the most widely marketed drugs in the world to treat osteoporosis but their anti-remodeling effect can cause osseointegration to fail.

Objective: this study aimed to evaluate bone quality during peri-implant repair in osteopenic rats, adopting an approach inverse to the conventional one in which prolonged treatment with alendronate sodium was initiated only after the installation of titanium implants.

Methodology: implants were installed in the tibias of 32 rats 14 days after ovariectomy (osteopenia). After 14 days, systemic treatment was initiated by gavage with a saline solution or alendronate. At 28 and 56 days after implantation, the rats received calcein (20 mg/kg, i.m.). They were administered alizarin red (20 mg/kg, i.m.) seven days before euthanasia. Euthanasia occurred in two periods, 42 and 70 post-implantation days.

Results: the highest implant removal torques were observed for the OVX ALE at 70 days (13.35 Ncm) and the OVX SAL at 42 days (11.63 Ncm). The expression of bone remodeling and resorption proteins (OPG/ RANKL) was higher in the alendronate-treated animals. In contrast, osteocalcin and bone sialoprotein were similar between the control and alendronate-treated groups. No parameter showed statistically significant variations (BV, BV.TV, Tb.Th, Tb. N, Tb.Sp, and i.S), with similar measurements between groups. Fluorochrome analysis showed active bone remodeling at the implant interface.

Conclusion: the alendronate treatment stabilized the bone-implant interface over time, suggesting a protective effect against osteoporotic bone loss despite a delayed initial response. In the long term, the group systemically treated with alendronate showed improved bone formation around the implants, outperforming the control group. However, future research is essential to prevent possible negative impacts on osseointegration in patients taking this medication.