Comparative evaluation of canal centering ability and transportation after preparation with various file systems in curved canals using cone beam computed tomography: An in-vitro study

Introduction: Nickel-titanium rotary files have greatly enhanced the quality of root canal instrumentation and evolved in various aspects over the years. Purpose: Comparative evaluation of canal centering ability and transportation after preparation with various file systems in curved canals using cone beam computed tomography. Materials and methods: 45 mandibular first molars with mesiobuccal canals having an angle of curvature ranging from 20° to 35° were selected. Fifteen teeth were allocated per group: Group 1: iRaCe, Group 2: ProTaper NEXT, Group 3: WaveOne GOLD. After decoronation, access cavity preparation and working length determination of mesiobuccal canals was done. Initial CBCT scans were taken in a small field of view to determine the root canal morphology before instrumentation. Three axial sections located at 3 mm, 6 mm and 9 mm from the root apex were selected and viewed in 0.2 mm slice thickness. After instrumentation, post-instrumentation scans were taken. The statistical analysis for the study was done using SPSS version-20.0. One-way ANOVA with Posthoc Tukey test was applied for inter-group comparisons at the coronal, middle and apical levels. Statistical significance was set at p < 0.05. Results: When the three systems were compared for transportation, no significant difference was demonstrated among them. All three groups showed statistically similar centering ratio. Conclusion: All the three file systems: iRaCe, ProTaper NEXT and WaveOne GOLD caused comparable extent of transportation in curved canals which was well within the acceptable limit. Clinical significance: Studies conducted on characteristics of new rotary files enable the clinicians to make an evidence-based choice of files. The three experimental rotary file systems, which differed in taper, metallurgy and manner of rotation, could be safely used in cases of challenging canal curvature because of satisfactory centering ability and minimum transportation.