Influence of Torque on Cutting Efficiency of Heat Treated NiTi Alloy Endodontic Rotary Files

This study was designed to evaluate the cutting efficiency of heat-treated endodontic file under two different torque setting 1.5 Ncm as a recommended torque and at a higher torque 4.5 Ncm. Material and method: 40 Race Evo sets of files were used to shape 400 acrylic resin canals with angle of curvature less than 30⁰ a length of 16 mm. Samples were divided into two groups depending on torque. Group A: (20) files tested under recommended manufacture torque 1.5 Ncm. Group B: (20) file were tested under higher torque 4.5 Ncm. Each group was further divided into two subgroups according to number of canals: Subgroup I: (10) Race Evo files were used to shape 8 canals. Subgroup II: (10) Race Evo files were used to shape 12 canals. The difference in the weight loss for each sample was calculated. Data were analyzed by Two-way ANOVA. Results: there was statistically significant difference between 8 canals and 12 canals (P≤0.05). With recommended torque showed statistically significantly higher mean of weight loss than high torque. With high torque showed statistically significantly higher cutting efficacy with 8 canals. Conclusions: Race Evo files showed higher cutting efficiency with recommended torque than high torque.