Immunohistochemical changes of heat shock protein 27 expression in the mouse periodontal tissues exposed to orthodontic mechanical stress

Orthodontic mechanical stress was exposed on mouse molars and histopathological changes as well as the expressions of HSP27 and p-HSP27 in the periodontal tissues were examined after removal of mechanical stress. The increased in mechanical stress up to 3 hours led to pathological changes that caused a space in between stretched periodontal ligament fibrous bundles and fibroblasts as well as narrowing of the periodontal ligament space. Degenerative changes were also occurred in the pressure side. Pathological changes did not only occur due to mechanical stress but also at the time of the release of mechanical stress exposure which increased over time. In the control group, both HSP27 and p-HSP27 were negative in the pressure side after mechanical stress was released 3 hours later. On the other hand, the tension side showed a strong positive reaction. The proteins were also expressed after 20 min, 1 hour, 3 hours and 9 hours. The strongest expression was observed 24 hours. A decreased in the intensity of expression was observed 3 days and 1 week later. The results suggest that HSP27 plays an important role in the recovery of injured cells in the periodontal tissues.