ABSTRACT
INTRODUCTION: This 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. METHODS: The rats were given oral risedronate at 0, 0.5, or 1.0 mg per kilogram per day for 4 weeks after the 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. RESULTS: In 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. CONCLUSIONS: Risedronate 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.
Subject(s)
Bone Density Conservation Agents/pharmacology , Etidronic Acid/analogs & derivatives , Glucocorticoids/adverse effects , Mandible/drug effects , Prednisolone/adverse effects , Anatomy, Cross-Sectional , Animals , Body Weight/drug effects , Bone Density/drug effects , Etidronic Acid/pharmacology , Male , Mandible/growth & development , Mandible/pathology , Minerals/analysis , Organ Size/drug effects , Osteoblasts/drug effects , Osteoblasts/pathology , Osteogenesis/drug effects , Osteoporosis/chemically induced , Osteoporosis/physiopathology , Periosteum/drug effects , Periosteum/growth & development , Periosteum/pathology , Rats , Rats, Wistar , Risedronic Acid , Time Factors , Tomography, X-Ray ComputedABSTRACT
OBJECTIVE: To investigate the effects of a low calcium diet on maxillofacial development by evaluating Bone Mineral Content (BMC) in the lower alveolar bones, femurs, and tibias and by performing cephalometry on growing rats. MATERIALS AND METHODS: Thirty 5-week-old male Wistar rats were randomly divided into 3 groups; the control group (n = 10) was given standard diet for 6 weeks, the low calcium/standard diet group (n = 10) was given a calcium-restricted diet for the first 4 weeks, and then a standard diet for the following 2 weeks, and the low calcium diet group (n = 10) was given the calcium-restricted diet for 6 weeks. After the rats were euthanized, heads and legs were fixed and cephalometry was performed. Next, mandibles, femurs and tibias were digitally photographed and the BMC was evaluated using our newly developed software. RESULTS: The BMC was decreased in all of the bone samples from the two groups that received restricted calcium. In the low calcium/standard diet group, the BMC recovered the most in the tibias and least in the lower alveolar bones. Development of the mandibles in the anterior-posterior direction was accelerated, while that in the superior-inferior direction was inhibited in those rats. CONCLUSION: The BMC reduction following calcium deficiency in the lower alveolar bone hardly recovers, so prevention is important. Development of the mandible in a superior-inferior direction is inhibited while that in an anterior-posterior direction is accelerated due to a calcium-restricted diet.
