Study On The Effect Of Green Or On The Vital Pulp After Full Crown Preparation

Objective To study the histologic effect of Green or on the vital pulp at different time after porcelain fused to metal(PFM) crown preparation, to observe the immunolocalization of heat shock protein70(HSP70) in the pulp, and to discuss the influence of Green or on the expression of HSP70 by comparison.Methods 30 pairs of human biscuspids in 20 patients, of which every 2 teeth were from the same patient and the same jaw, scheduled to be extracted for the orthodontic reasons were prepared for PFM. These 30 pairs of teeth were divided into 3 groups according to the periods of post-operative: group A-extracted after 1 week, group B-extracted after 2 weeks, group C-extracted after 3 weeks. Every 2 teeth from the same patient and the same jaw were randomly divided into 2 groups. In the testing group-Green or was applied on the surface of preparations before the temporary crowns were cemented with zinc oxide eugenol. In the control group–the temporary crowns were cemented with zinc oxide eugenol. All the teeth were extracted at 1 week 2 week or 3 week and prepared according to normal histologic techniques.(1)Serial sections were stained with H-E and evaluated blindly for three histological features: imflammatory cellular response, tissue disorganization, tertiary dentine formation. The remaining dentine thickness(RDT) was measured for each tooth specimen using a light microscope adapted to a video-camera. The relation between the RDT and the pulpal response was evaluated. (2)Immunohistochemistry was applied to observe the location of HSP70 in the pulp.The differences of the amount of HSP70 were determined by computer image analysis system.Results (1)After the period of 1 week of post-operative, the control group caused more intense imflammatory cellular response than in the testing group(p﹤ 0.05).Whereas little difference of pulpal response was found in the control group and in the testing group after the period of 2 week and 3 week(p﹥0.05).When the RDT was more than 0.5mm,there was no correlation between the RDT and pulpal response. When the RDT was less than 0.5mm, the pulpal response was intense distinctly. The RDT of the three specimens(one in the testing group, the other two in the control group) ,which showed tertiary dentine secretion, was most thinnest of the all.(2) After the period of 1 week of post-operative, the expression of HSP70 in the control group was higher than in the testing group(p﹤0.05). Whereas after the period of 2 week and 3 week, little difference of the expression of HSP70 was detected between the control group and the testing group(p﹥0.05).Conclusions (1)Green or distinctly relieves the intensity of the vital pulpal imflammatory response after full crown preparation.(2)HSP70 can protect pulp cells and increase the ability of resistance injury in the stage of pulpal inflammatory response.HSP70 might join in tertiary dentine formation in the later stage.