AimAfter immediate teeth separation, expression of HSP27 in the mouse dental pulp was examined. Immunohistochemistry was performed to examine the incidence of HSP27 expression.Materials and methodsA total of 36 8-week-old ddY mice were used as experimental subjects and a wedge was inserted in between maxillary right molars. The wedge was removed 30 min or 3 h after insertion. Animals were immediately sacrificed after the removal of wedge or until 1 week later and serial sections from paraffin-embedded tissues were prepared. Immunohistochemistry was carried out to examine the expression of HSP27. The untreated side served as the control.ResultsIn the control group, the endothelial cells and some pulp fibroblasts weakly expressed HSP27 suggesting that the expression is due to mechanical stress brought about by physiological masticatory force and pressure from the tongue. In both 30 min and 3 h experimental groups, HSP27 expression was highest at 24 h after wedge removal and the expression remained the same or started to decrease thereafter. The expression decreased at the same level as that of the control group 1 week after wedge removal.ConclusionHSP27 may serve as an indicator of stimulus strong enough to show its expression.

We examined change of Runx2 and ALP expression in mouse tooth pulp which exposed to teeth separation experiment by immunohistochemistry as a model for conservative dentistry treatment. 8-week-old 36 male ddY mice were used and wedge was inserted between upper 1st and 2nd molars. The wedge was removed 30 minutes as well as 3 hours after the insertion and the samples were prepared extending up to 1 week of time period for regular histopathological and immunohistochemical examinations for ALP and Runx2 expression. The opposite sides without wedge insertion were taken as controls. In the control group pulp, weak expressions of Runx2 and ALP in the vessel endothelial cells as well as the pulp cells were revealed, suggesting the appearance of these genes upon mechanical stress induced by mastication and tongue pressure etc. On the other hand in the experiment group, Runx2 expression increased both in 30-minute and 3-hour teeth separation group. The expression became maximum at 24 hours. Then it gradually decreased and became similar level with the control group at 1-week after the wedge insertion. Similarly ALP expression increased after the wedge insertion and was maximum at 24 hours and then gradually decreased to the levels similar with the control group. These results suggest that when immunohistochemical expression of Runx2 as well as ALP was used as an index, no severe damage occur upon clinical application of wedge insertion.

We examined the change of HSP70 expression in the mouse dental pulp which was exposed to experimental teeth separation by immunohistochemistry as a model for conservative dental treatment. Eight week-old 18 male ddY mice were used and a wedge was inserted between upper 1 st and 2 nd molars for 3 hours. In the experimental group, HSP70 expression increased in the dental pulp tissues. The expression was the greatest at 24 hours after which it gradually decreased to become similar to the level of the control group at 1 week. These results suggest that when immunohistochemical expression of HSP70 is used as an index, almost no severe damage occurs upon clinical application of a wedge insertion.

We examined immunohistochemical expression of Chromogranin A (CgA) in the mouse dental pulp and the periodontal tissues, which exposed to 3 hours immediate teeth separation. In the experimental group, CgA positive staining products were frequently detected in the periodontal fibroblasts and endothelial cells, and also detected in the dental pulp cells. The positive reactions were stronger than that of control specimens. The data suggests that induced expression was due to the mechanical stress of wedge insertion.