Effects of risedronate on cortical and trabecular bone of the mandible in glucocorticoid-treated growing rats

IntroductionThis study was performed to estimate the effects of risedronate on mandibular bone density, bone structure, and bone metabolism in established glucocorticoid-induced osteoporosis in growing rats.MethodsThe rats were given oral risedronate at 0, 0.5, or 1.0 mg per kilogram per day for 4 weeks afterthe administration of oral prednisolone at 30 mg per kilogram per 2 days for 6 weeks. Trabecular and cortical bone masses were analyzed by using peripheral quantitative computed tomography, and bone structure and bone formation were measured by using static and dynamic histomorphometry.ResultsIn trabecular bone, risedronate improved the prednisolone-induced decreases in bone cross-sectional area and bone mineral content. Risedronate increased bone density and also formed dense bone microarchitecture by reducing the bone turnover rate. In cortical bone, risedronate improved the prednisolone-induced decreases in bone cross-sectional area and bone mineral content without affecting bone density by increasing the mineralizing surface.ConclusionsRisedronate improved prednisolone-induced retardation of trabecular and cortical bone growth, but the bone turnover in these 2 sites was regulated differently in the growing rat mandibles.