General investigation of malocclusion in the aspect of age-related expression mechanism

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Extracellular matrixOcclusal hypofunction of rat unilateral mandibular molars was induced by extraction of the opposing teeth, and immunohistochemical analyzes were performed to clarify the influence of occlusal hypofunction on the changes of proteoglycan content in the periodontal ligament.proteoglycan decreased in the periodontal ligament due to loss of occlusal function, and these results suggest that proteoglycans are closely related to occlusal function and play important roles in tissue homeostasis or tissue remodeling.MicrovasculatureWe examined the effect of occlusal stimuli on the microvasculature of the periodontal ligament using a model of occlusal hypofunction in rat molars. The occlusal hypofunction caused narrowing of the periodontal membrane and reduction in the vessel size with decrease in the number of blood vessles. In this study, a mechanism is revealed that hypofunction would result in increase of the expression of endothelin, a potent vasoconstrictive factor, furth … More ermore it also suggested the relation to expression of nitric oxide synthase(NOS), a vasodilator factor.Periodontal mechanoreceptorsThe neurophysiological properties of the periodontal mechanoreceptors were studied using an in vitro jaw-nerve preparation. Results of this study have demonstrated the effects of experimental occlusal hypofunction on the periodontal mechanical signaling. Moreover, changes related to growth and development have also been investigatedActivity of bone formationIn order to clarify the mechanism of bone remodeling under mechanical stress, cultured osteoblastic-cells were subjected to shear stress, in which we have revealed that the enhancement of intracellular Ca^<2+> depended on the property of stretch-activated channel and were modulated by the cytoskeleton such as actin filament.We also elucidated the hypofunctional condition of the root, remodeling of the alveolar bone and the physiological tooth movement in rats. And, the experimental tooth movements under hypofunctional condition have made it more obvious that light orthodontic forces contribute to the conservation of sound periodontal tissue. Less