Gentlefile Versus Protaper in the Shaping Ability in Simulated J-shaped Root Canals

Abstract

Background: The aim of this study was to compare the shaping ability of Gentlefile (GF), a unique stainless-steel (SS) rotary system, and ProTaper (PT), a popular mechanical nickel-titanium (NiTi) system, in J-shaped simulated canals. Methods: Thirty-three resin blocks with a J-shaped canal were selected and randomly divided into 3 groups according to tip diameters: GF red (#23); PT F2(#25); GF blue (#26). They were prepared in one training model which imitated human dentition. Specimens were photographed by a dental operating microscope before and after preparation. The images were processed and measured using professional software. Centering ability and canal transportation were calculated, canal aberration and instrument separation were also recorded. Results: The GF system was significantly less transported than PT F2 in the apical and middle section. What’s more, better centering ability of GF was shown in all sections, including the coronal level. However, there was no difference between GF red and GF blue based on above criteria. Two cases of instrument separation of GF were noted.Conclusion: Under the conditions of this study, the two GF files showed better shaping ability, but were more easily separated than PT F2. As a novel SS rotary system, Gentlefile is more flexible to prepare narrow and curved root canals by scraping dentin with high-speed rotation, which might help remove smear layer much thoroughly and cause less dentin microcracks.