Ovariectomy induces osteoporosis in the maxillary alveolar bone: an in vivo micro-CT and histomorphometric analysis in rats

Abstract

Objective: To investigate whether porotic changes occur in maxillary alveolar bone in ovariectomized rats.

Methods: Thirty-two 6-week-old female Sprague-Dawley rats were divided into an ovariectomy group (OVX) and a sham-ovariectomy group (sham). Twelve weeks after surgery, maxillae of 16 rats (eight OVX and eight sham) were analyzed by micro-CT. Inter-radicular alveolar bone of the maxillary first molar was reconstructed and analyzed. The remaining 16 maxillae were used for histochemistry, including hematoxylin-eosin staining and tartrate-resistant acid phosphatase enzyme staining.

Results: Three-dimensional reconstructed images of the irregular alveolar bone showed an intuitive view of porotic changes in the OVX group. The alveolar bone in OVX rats had a porous microarchitecture including lower bone mass and a looser structure of more widely separated trabeculae. Bone mineral density (BMD), bone volume fraction (BV/TV), and trabecular thickness (Tb.Th.) were significantly lower in the OVX group than those in the sham group (P < 0.05). Trabecular separation (Tb.Sp.) increased significantly in the OVX rats compared to the sham rats (P < 0.05). Histomorphometric analysis of alveolar bone also revealed porotic changes in the OVX rats. Bone area ratio significantly decreased in the OVX group compared with the sham group (P < 0.01). There were also more osteoclasts present in the alveolar bone of OVX rats compared to sham rats (P < 0.05).

Conclusion: Ovariectomy induces osteoporosis in maxillary alveolar bone in rats, which may be related to the increased number of osteoclasts.

Keywords: alveolar bone; micro-CT; osteoporosis; ovariectomy.