Comparative Evaluation Of The Shaping Ability Of Four Nickel-titanium Rotary Instruments In Resin Simulated Severely Curved Root Canals

Abjective: The purpose of this study is to compare the shaping ability of Pro Taper Universal,Reciproc Blue,Hy Flex EDM,and ORODEKA instruments in resin simulated severely curved root canals.Methods and Materials: A total of fourty resin blocks with severely curved root canals were randomly assigned to four groups(n=10),Each group was prepared with Pro Taper Universa((Group1),Reciproc Blue(Group2),Hy Flex EDM(Group3),and ORODEKA(Group 4)according to the manufacturers’ instructions.The preparation time of each group was measured,excluding time for irrigating and changing instruments.Pre-and post-instrumentation photographs were taken by SLR camera and superimposed with software,and then measured the ability of the instruments to remain centered in the prepared canals at 10 levels and the changes in canal curvature.SPSS software version22.0 was used for data analysis.Results: No instruments fractured were observed during root canal preparation,The preparation time of Group 2 was(77.87±1.33)s,whereas those of Groups 1,3,and 4 were(90.25±3.17)s,(81.60±1.44)s,and(94.65±5.26)s,respectively;and the data of group 2was significantly shorter than Group 1 and Group 4(P<0.05),and the data of Group 3was significantly shorter than Group 4(P<0.05).No significant difference between other groups.There was no statistically significant difference in the canal curvature of the four groups(P>0.05).At the 1,2 mm point,the transportation of Group l was significantly greater than other three groups(P<0.05);At the 3mm point,the centering ability of Group 2 was significantly better than Group 1(P<0.05),but there was no significant difference compared with the other two groups;At the 4,5mm point(at the curved part),the transportation of Group 2 was significantly greater than other three groups(P<0.05).At the 6～10mm point(at the straight part),there were no significant difference in canal transportation among the four groups.Conclusions: Within the range of the experiment.Generally,these four instruments can maintain original canal curvature well.Reciproc Blue can perform root canal preparation quickly and efficiently,and expresses superior centering capability in the apical part of the canal;The centering ability of Hy Flex EDM and ORODEKA at the curved part relatively better than the other two groups,and the preparation time of Hy Flex EDM was shorter than ORODEKA.