Single file reciprocating technique using conventional nickel-titanium rotary endodontic files

This study was aimed to evaluate the applicability of a reciprocating movement technique with conventional nickel-titanium files for root canal preparation. Forty-four simulated canals in resin blocks were used in this study and divided as following four groups according to the instruments used and preparation methods. Group CP (n = 12) and CR (n = 12) were instrumented with continuous rotation using four files of ProFile and RaCe, respectively. Group RP (n = 10) and RR (n = 10) were instrumented with a reciprocation movement by using a single ProFile and RaCe file, respectively. The resin blocks were scanned before and after instrumentation, and the images were superimposed. To compare the efficiency of canal shaping, the preparation time, and centering ratio were calculated. Morphologic changes of tested files were examined by scanning electron microscopy (SEM). Data were analyzed by ANOVA and Duncan's post hoc test at p < 0.05. The preparation time was markedly shorter in Groups RP and RR than in Groups CP and CR. No significant difference in the centering ratio was noted between groups. Although the files used for Groups CP and CR showed no distortion under the SEM evaluation, the files used for Groups RP and RR had considerable torsional distortion. This study suggests that the reciprocating instrumentation technique using conventional nickel-titanium rotary file systems might have a comparable efficacy for the root canal shaping with reduced shaping time. Although the reciprocating technique seems to be an effective alternative to the conventional rotation technique, the risk of torsional distortion and fracture should be considered before clinical application.