Currently, various Nickel-Titanium rotary files are used in endodontic treatment, but there is no one perfect system that can be applied to any clinical situation. Therefore, the combined uses of various file systems which can emphasize the advantages of each system are introduced as hybrid instrumentation.

The ProTaper system is efficient in body shaping and apical pre-enlargement but is reported to have more possibility of transportation and produce more aberrations and deformation in more or less severe curved canals. Recently, new ProTaper system (ProTaper Universal) with different configuration and cross-sectional design to overcome the week points of ProTaper have been marketed.

The purpose of this study was to compare and evaluate the shaping abilities of ProTaper, ProTaper Universal system, and two hybrid methods using S-series of ProTaper Universal and Hero Shaper or ProFile.

The time lapses for instrumentation were measured and the used files were inspected for distortion. The pre- and post-instrumented root canals were scanned and superimposed to evaluate the aberrations and reduction of root canal curvature and change of radius of canal curvature. The increased canal width and apical centering ratio were calculated at 1, 2, 3, 4 and 5 mm levels from apical foramen.

Under the conditions of this study, the ProTaper Universal seems to have better shaping ability than ProTaper in terms of instrumented width and instrumentation time. It may be suggested that the ProTaper Universal system is efficient as much as hybrid instrumentation using ProTaper and other constant-tapered NiTi file systems in highly experienced operators.

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.