Effect of hypoestrogenism on the alveolar bone and periodontal ligament

Background: Previous studies have shown that ovariectomy can alter bone structure, especially in the maxilla, as well as the periodontal ligament at the molecular level, and lead to cementum accumulation in the apical region. Materials and Methods: The present study was conducted to elucidate the molecular mechanisms involved. For the experiment, 12 BALB/c mice were randomly assigned to two groups: a sham surgery group and an ovariectomy group. In the sham surgery group, the ovaries were exposed and then repositioned without removal, whereas in the ovariectomy group, the ovaries were surgically excised. Twelve weeks postsurgery, the mice were sacrificed by an overdose of general anesthesia. Subsequently, the mandibles and maxillae were dissected for histological analysis. Samples were examined under a Nikon^® microscope using ToupView to measure the periodontal ligament (×100) and ImageJ software for cell counting (×400). Results: The ovariectomy group exhibited an increase in osteoclastic cell number, particularly in the mesial alveolar crest and the interradicular bone of the maxillary and mandibular regions. In addition, within the same group, widening of the periodontal ligament fibers, dilation of blood vessels, structural alterations in the periodontal ligament, as well as cementum accumulation in the apical region, were observed. Conclusion: Estrogen deficiency increases the number of osteoclasts, alters their orientation, widens the periodontal ligament, and leads to the accumulation of apical cementum.