Distributional Variations in Trabecular Architecture of the Mandibular Bone: An In Vivo Micro-CT Analysis in Rats

PURPOSE To evaluate the effect of trabecular thickness and trabecular separation on modulating the trabecular architecture of the mandibular bone in ovariectomized rats. MATERIALS AND METHODS Fourteen 12-week-old adult female Wistar rats were divided into an ovariectomy group (OVX) and a sham-ovariectomy group (sham). Five months after the surgery, the mandibles from 14 rats (seven OVX and seven sham) were analyzed by micro-CT. Images of inter-radicular alveolar bone of the mandibular first molars underwent three-dimensional reconstruction and were analyzed. RESULTS Compared to the sham group, trabecular thickness in OVX alveolar bone decreased by 27% (P = 0.012), but trabecular separation in OVX alveolar bone increased by 59% (P = 0.005). A thickness and separation map showed that trabeculae of less than 100 μm increased by 46%, whereas trabeculae of more than 200 μm decreased by more than 40% in the OVX group compared to those in the sham group. Furthermore, the OVX separation of those trabecular of more than 200 μm was 65% higher compared to the sham group. Bone mineral density (P = 0.028) and bone volume fraction (p = 0.001) were also significantly decreased in the OVX group compared to the sham group. CONCLUSIONS Ovariectomy-induced bone loss in mandibular bone may be related to the distributional variations in trabecular thickness and separation which profoundly impact the modulation of the trabecular architecture.