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 100μm increased by 46%, whereas trabeculae of more than 200μm 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 200μm 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.