Different Instruments And Methods To Prepare And Then The Treatment Of Experimental Study Of Curved Root Canals

Objective:The aim of this study is to compare the cleaning effectiveness and shaping ability of preparing curved root canals retreatment by using stainless steel K-file,nickel-titanium alloy K-file and ProTaper nickel-titanium instruments.To analyse the merit and defect of the three types of instruments and evaluate which one has the future .In order to provide the sicientific basis for choicing right types and ways of instruments in preparing root canals.Methords:60 extracted premolars with single root canal and curvature of 20°～45°were divided into two groups of 30 each group, resinifying therapy group and root canal therapy group .30 extracted premolarswith model of resinifying and root canal therapy each group were were divided into three groups.The root canal of each group were prepared with stainless steel K-file,nickel-titanium alloy K-file and ProTaper nickel-titanium instruments.60 root canals were scanned before and after instrumentation using computed tomography(CT) on cross section. Then the images were compared and the effects of root canal instrumentation evaluated.Observing by the scan electron micro-scope.According to the amount of smear layer and dentinal debris in root canals.Reasults were analyzed statistically with SPSS11.5 statistical software .Results: Compared the difference of cross section before and after instrumentation using computed tomography(CT),there was significant difference between stainless steel K-file,nickel-titanium alloy K-file and ProTaper nickel-titanium.Observing by the scan electron micro-scope,in apical third,there was significant difference between stainless steel K-file,nickel-titanium alloy K-file and ProTaper nickel-titanium on smear layer and dentinal debris elimination .In the middle and coronal third , there was significant difference between stainless steel K-file,nickel-titanium alloy K-file and ProTaper nickel-titanium on smear layer and dentinal debris elimination , no sifnificant differences were observed between stainless steel K-file,nickel-titanium alloy K-file.Conclusions:The ability of ProTaper nickel-titanium instruments to clean and shape curved root canals retreatment was superior to the conventionl K-file and nickel-titanium.ProTaper nickel-titanium instruments had the best ability of cleaning in preparing of apical third.