Changes in the microstructure of the rat alveolar bone induced by unilateral molar extraction and estrogen deficiency

The present study was designed to assess compensatory changes in the microstructure of alveolar bone induced by occlusal force and estrogen deficiency using micro-computed tomography, which enables us to analyse bone mass and architecture in detail, in combination with a histomorphometric analysis.Fifteen 10-week-old female Wistar rats were used. We created hypofunctional teeth in the right molar region of the mandible after abolishing occlusal force by extracting the right maxillary molars and bilateral ovariectomy was undergone. Analyses of the microstructure and bone resorption of the alveolar bone were carried out by the micro-computed tomography (micro-CT) and histomorphometric analyses.The results of micro-CT and histomorphometric analyses showed that a decrease in occlusal force stimulated bone resorption and accelerated the fragility of the bone structure in the alveolar bone around the teeth, and also shortened the mean intercept length of the trabecular bone in the direction of the tooth axis. However, estrogen deficiency appeared to have few effects, based on the results of micro-CT and histological morphometric analyses.These results suggest that occlusal force is essential for female rats with sexual maturation during short time period to maintain the structure and regulation of alveolar bone in rats.