Alendronate May Protect Against Increased Periodontitis‐Related Bone Loss in Estrogen‐Deficient Rats

Background: The aim of this study was to evaluate the impact of alendronate (ALD) and estrogen (EST) therapies and their withdrawal on bone loss in experimental periodontitis in ovariectomized rats. Methods: Eighty‐seven Wistar rats were divided into six groups: group 1 (N = 15): sham surgery; group 2 (N = 15): ovariectomy (OVX); group 3 (N = 15): OVX plus alendronate administration for 80 days (AT); group 4 (N = 14): OVX plus alendronate administration for 40 days (AW); group 5 (N = 14): OVX plus 17β estradiol administration for 80 days (ET); and group 6 (N = 14): OVX plus 17β estradiol administration for 40 days (EW). Twenty‐one days after ovariectomy or sham surgery, one mandibular molar was randomly assigned to receive a ligature, while the contralateral tooth was left unligated. Sixty days later, the animals were sacrificed and the specimens processed. Results: OVX presented a direct impact on alveolar bone, regardless of plaque accumulation and significantly increased bone loss resulting from periodontitis ( P <0.05). The effect of OVX on unligated sites was significantly reduced by AT, AW, and ET ( P <0.05), but not by EW ( P >0.05). In addition, alendronate administration (AT/AW) significantly reduced the impact of OVX on periodontitisrelated bone loss ( P <0.05), while estradiol did not ( P >0.05). Conclusion: Within the limits of this study, alendronate administration, but not estrogen replacement, may protect against the impact of estrogen deficiency on alveolar bone presenting a signi‐ ficant residual effect after its withdrawal. J Periodontol 2004;75: 1196‐1202 .