Comparative Evaluation of the Shaping Ability of Five Different Nickel-Titanium Rotary File Systems in Simulated Canals

Objectives: The aim of this study was to compare the simulated canal shaping efficiencies of five different NiTi rotary file systems. 
Materials and Methods: In the study, 100 transparent resin blocks with J-shaped canals were randomly divided into five groups (n=20). Simulated canals were shaped with VDW.Rotate (VR), TruNatomy (TRN), HyFlex CM (HF), EdgeFile X7 (EF), or ProTaper Next (PTN) files. Ten measuring points were detected on the pre- and post-preparation images taken from the blocks and superimposed. After preparation, the total canal width and the amount of transportation were calculated for the determined measuring levels. Zipping and ledge formation, instrument fracture and deformation, and change in working length were evaluated. The data were statistically analyzed with the Kolmogorov-Smirnov test, one-way ANOVA, Tukey test, Chi-Square test, and a Monte Carlo version of the Fisher Exact tests. The error level was taken as 0.05. 
Results: There were significant differences between the groups at all measuring levels in terms of total canal width after instrumentation (p = 0.001). Significant differences in the amount of transportation were found between the groups (p = 0.001) except at levels 4 (p = 0.169) and 10 (p = 0.054). Zip and instrument fractures did not occur in any group. 3 EF size 25/.04 files were deformed (p = 0.021). There was no significant difference between the groups in terms of ledge formation and working length change (p > 0.05). 
Conclusions: According to findings obtained in the study, transportation occurred at all 10 measuring levels with all file systems used. HF and EF systems were found to be more reliable in terms of transportation in the middle and coronal regions. Wider canal preparation was obtained with the PTN system in the middle and coronal regions.