Alendronate therapy may be effective in the prevention of bone loss around titanium implants inserted inn estrogen-deficient rats

Background: This study evaluated whether alendronate (ALD) influences bone healing around titanium implants inserted in ovariectomized rats and whether it provides a residual effect after its withdrawal. Methods: Bilateral ovariectomies were performed in 87 Wistar rats and one screw-shaped titanium implant was placed in the tibiae. The animals were divided into the following groups: group SHAM (N = 15): sham surgeries; group OVX (N = 15): ovariectomy; group AT (N = 15): OVX plus alendronate administration for 80 days; group AW (N = 14): OVX plus alendronate administration for 40 days; group ET (N = 14): OVX plus 17 beta estradiol administration for 80 days; or group EW (N = 14): OVX plus 17 beta estradiol administration for 40 days. Bone-to-implant contact (BIC), bone area (BA) within the limits of implant threads, and bone density in a 500 mu m-wide zone lateral to the implant (BD) were obtained and measured for the cortical (zone A) and cancellous (zone B) regions. Results: In zone A, data analysis showed no significant differences among the groups regarding BIC and BD (P > 0.05), and a slight beneficial effect of estradiol on BA when compared with the OVX, EW, and AW groups (P < 0.05). In zone B, OVX negatively impacted bone healing around the implants, resulting in reduced BA and BD (P < 0.05). ALD (continuous/interrupted) and estradiol (only continuous) positively affected BIC, BA, and BD, resulting in values at the same level as the control group (SHAM). Conclusions: ALD may prevent the negative influence of estrogen deficiency on bone healing around titanium implants inserted in OVX rats. This positive effect, in contrast to estradiol, is sustained following its withdrawal.