The Comparative Study Of Hsp70Expression In Rabbits Dental Pulp After Cavities Preparation By Er: YAG Laser And High Speed Drill

Objective: Cavities preparation were made on rabbit teeth using two different tools,which were Er：YAG laser and high speed drill. After cavity preparation by twokinds of stimulus, heat shock protein70(HSP70) expression by immunohistochemicalstaining were observed to evaluate the different effects on dental pulp,and thechanging over time.Method:32male rabbits were used in this study, divided into2groups randomly,which were laser group(cavities were prepared using Er: YAG laser) and drillgroup(cavities were prepared using high speed drill),16rabbits in each group.Thecentral incisors of right mandibular were chosen to prepare cavities, after that,4rabbits were randomly killed on1,3,7,14d respectively for each group to make pulpparaffin sections for immunohistochemical study. HSP70expression were examinedby measuring Mean Optical Density values(MOD), all the present data were analysedby SPSS17.0software.Results:1.The MOD values of HSP70expression in the high speed drill group wassignificantly different with the Er：YAG laser group（P＜0.05）；the MOD valuesin each time point were markedly different（P＜0.05）;moreover,the treatmentfactor and the time factor had interaction effects.2. On the1st,3rd and7th day aftercavities preparation, the MOD values of HSP70expression in the high speed drillgroup were significantly higher than the Er：YAG laser group（P＜0.05）；and14days after cavities preparation, the MOD values in the two groups had no significantdifference（P＞0.05）.3. In the high speed drill group, the1d and the7d had nodifference on the MOD values（P＞0.05）；however, the rest multiple comparisonin time points existed difference（P＜0.05）.4.In the Er：YAG laser group, the7dand the14d had no difference on the MOD values（P＞0.05）；however, the restmultiple comparison in time points existed big difference（P＜0.05）.Conclusion:1. There is less histopathology change of the dental pulp in the Er：YAG laser group than the high speed drill group after cavity preparation,the changeof the expression of HSP70is as well.2. The Er：YAG laser group takes less time for restore the histopathology change of the dental pulp to normal than the high speeddrill group after cavity preparation,the change of the expression of HSP70is as well.