Effects of bisphosphonate on the mandible of rats in the growing phase with steroid‐induced osteoporosis

Abstract

The objective of this study was to investigate the effects of bisphosphonate on the mandible of rats in the growing phase with steroid-induced osteoporosis, and to estimate the biomechanical response in the mandibular bone. Eight-week-old male Wistar rats (n = 50) were assigned to a 6-week control (Co-6) group, 6-week steroid (St) group, 9-week control (Co-9) group, 9-week steroid + standard diet (StSD) group, or 9-week steroid + standard diet + bisphosphonate (StSDBp) group. The mandibular bone was evaluated by two-dimensional bone density measurement (PDS-15), three-dimensional pQCT, and quantitative analysis of Ca, P, Mg, and Zn using a sequential high frequency plasma spectrometer (ICPS-8000). In PDS-15 analysis, the bone density converted to aluminum equivalent was higher in StSDBp group when compared with the StSD group, and no significant difference was observed in bone density between St group and Co-6 group. In pQCT analysis, trabecular bone density and mineral content were significantly higher, while all other bone parameters were significantly lower in St group when compared with the Co-6 group. The densities of trabecular and cortical bones, mineral content and cross-sectional area of cortical bone, and non-invasive stress strain index with reference to x and yaxes were higher in StSDBp group than in StSD group. In quantitative analyses, Ca and P were markedly higher in StSDBp group than in StSD group, while there were no differences in Mg and Zn. Bisphosphonate treatment increases trabecular and cortical bone parameters in the mandible of growing rats with steroid-induced osteoporosis.