Three-dimensional Changes of the Mandible and Alveolar Bone in the Ovariectomized Rat Examined by Micro-focus Computed Tomography

Abstract

To clarify the changes of the mandible and alveolar bone in postmenopausal osteoporosis, we examined the changes of structure in mandible and alveolar bone of ovariectomized (OVX) rats. Twelve female Wistar rats (25-week old) were divided into two groups equally. Nine weeks after ovariectomy, we examined the mandibles of OVX and sham control (Sham) rats by micro-focus computed tomography (μCT). Bone volume and trabecular thickness in OVX group were significantly less than those in Sham group, while the trabecular separation in OVX group was significantly wider than that in Sham group. Three-dimensional images from the μCT of the mandible demonstrated a reduced bone volume of the mandibular body in the region of the first molar as well as the inter-radicular septum of the first molar in OVX group. The incisor alveolar bone at the interface between the incisor and the bone marrow in OVX group was significantly thinner than that in Sham group. However, there was no significant difference in the thickness of the medial side of the incisor alveolar bone that did not contain or face the bone marrow. These findings demonstrate that the mandibular bone loss in the OVX rats is predominant adjacent to the bone marrow, suggesting bone loss in postmenopausal osteoporosis occurs mainly at the endosteal surface in mandible.