The purpose of this study was to compare and evaluate the shaping abilities of various hybrid instrumentation method using constant tapered file systems with ProTaper® S1 and the difference between experts and inexperienced clinicians in use of NiTi file.

Three hybrid methods used in this study were composed of ProTaper® S1 and K-Flexofile® (group S), ProTaper® S1 and HeroShaper® (group H), and ProTaper® S1 and ProFile® (group P), respectively. The ProTaper®-alone method (group C) was introduced as a control group.

After canal preparation, the lapse of time was recorded. The images of pre- and post-operative canal were scanned and superimposed. Amounts of instrumented canal widths and centering ratio were measured at apical 1, 2 and 3 mm levels and statistical analysis was performed.

In this study, both of the group C and S took more time to prepare canals than other groups. Inexperienced operators required more time for the entire preparation with the groups C and H than the experienced (p < 0.05). And the centering ratio of group P were preferable to ProTaper®-alone method or the hybrid technique using stainless steel files. As such, within experienced operators, group H also showed better results in addition to the group P.

Under these condition, the hybrid methods of each the ProFile® system and HeroShaper® with ProTaper® are recommendable comparative to ProTaper®-alone method. According to the results, the hybrid instrumentation method is a more appropriate method of canal preparation than single file system for narrow or curved canals.