Short-term etidronate treatment prevents glucocorticoid-induced bone debility of the mandible in growing rats.

To analyse the effects of short-term treatment with etidronate on the glucocorticoid-induced retardation of bone growth and deterioration of bone structure in the prepubertal rat mandible. Fifty 5-week-old male rats were divided into five groups. Etidronate or vehicle treatment (5 mg/kg/day, daily, subcutaneous injection) was initiated after glucocorticoid administration (30 mg/kg/day, on alternate days, orally) for 6 weeks and was continued for 3 weeks. Then, bone growth was measured using lateral cephalometric analysis. Peripheral quantitative computed tomography was used to determine bone density, bone cross-sectional area and bone strength. Glucocorticoid-treated rats had significantly lower body weight, mandibular length, cortical bone density, bone strength and cross-sectional area in trabecular and cortical bone, but had significantly higher trabecular bone density than untreated rats. No significant difference in mandibular height was observed between the glucocorticoid-treated group and the untreated control group. Etidronate treatment improved the glucocorticoid-induced decrease in bone strength and increased density in trabecular and cortical bone above the untreated control level, but had no significant effects on the reduction in mandibular length. These findings suggest that etidronate can potentially reverse the glucocorticoid-induced deterioration of internal bone structure, but has no beneficial effects on the glucocorticoid-induced retardation of bone growth in the growing rat mandible.