Effect of the Glide Path Establishment on the Torque Generation to the Files during Instrumentation: An In Vitro Measurement

Introduction: The purpose of this study was to compare in vitro torque generation during instrumentation with or without glide path establishment. Methods: Endo-training resin blocks with J-shaped canals were randomly divided into 2 groups according to glide path establishment (with or without) and subdivided into 2 subgroups with shaping instruments (WaveOne [Dentsply Maillefer, Ballaigues, Switzerland] or WaveOne Gold [Dentsply Maillefer]) (n = 15). For the glide path–established group, the glide path was prepared using ProGlider (Dentsply Maillefer). During the instrumentation with WaveOne or WaveOne Gold, in vitro torque was measured. The acquired data were analyzed with software. The maximum torque and total torque (the sum of the generated torque) were calculated. The data were statistically evaluated using 2-way analysis of variance and the Duncan post hoc comparison to examine any correlation of torque generation with glide path establishment and nickel-titanium instruments. The significance level was set at 95%. Results: The generated total torque by WaveOne Gold was significantly reduced by glide path establishment (P <.05), whereas glide path establishment did not induce significant changes in the maximum torque for both file systems. WaveOne Gold with a glide path showed the lowest total torque generation among all groups (P <.05). WaveOne generated a higher maximum torque than WaveOne Gold regardless of the establishment of a glide path (P <.05). Conclusions: Under the limitations of this study, glide path establishment and the mechanical property of instruments have a significant influence on torque generation. It is recommended to create the glide path and use a flexible file to reduce torque generation and, consequently, the risk of file fracture and root dentin damage.