Effect of Sodium Hypochlorite Irrigation with and Without Surfactant on Maximum Operative Torque and Vertical Force of Nickel-Titanium Endodontic Instruments

Objectives: This study aimed to evaluate the effects of root canal irrigation on maximum operative torque and vertical force of Wave One Gold Primary (WOG), Reciproc Blue R25 (RB) and Protaper Next X2 (PTN) endodontic rotary instruments during simulated root canal preparation in the presence and absence of a surfactant “benzalkonium chloride”. Material and methods: A custom-made automated irrigation and torque/force analyzing device connected with endomotor was used for the study. Acrylic resin blocks with simulated curved root canals of 35° were randomly assigned to 6 groups for each file. The following irrigants were used during simulated root canal preparation with continuous rotation or reciprocation motion with pecking mode: 5% NaOCl and 5% NaOCl with 0.084% benzalkonium chloride. Maximum torque and vertical force values of files were recorded during preparation. Results: BAC addition to NaOCl did not significantly affect maximum torque values of instruments (p>0.05). WOG generated lowest torque value compared with PTN and RCB in both groups (p<0. 05). RB generated higher vertical force compared with WOG and PTN instruments in NaOCl+BAC group. The surface modifier decreased the maximum force value of WOG instrument (p<0.05). Discussion: Surfactan addition to NaOCl had no negative effects on maximum torque and force of the instruments.