Introduction: This study aimed to compare the shaping ability and cutting efficiency of Trunatomy, Protaper Next and 2Shape file systems in preparing severely curved canals. Methods: Forty-five mandibular mesiobuccal canals with 40-60 degrees of curvature were divided into three equal groups: Trunatomy, Protaper Next and 2Shape. Root canal instrumentation was done according to the manufacturers' instructions of each NiTi system. Pre- and post-instrumentation images were taken using cone beam computed tomography to measure canal transportation, centering ability, dentin thickness and canal curvature radius and volume. Pre- and post-instrumentation weights were measured using an analytical scale. Results: Trunatomy had significantly the lowest values of canal transportation, amount of removed dentin and percent change in canal curvature radius and volume. Protaper Next had significantly the highest buccolingual canal transportation. There was no significant difference among the three systems in canal centering. Trunatomy significantly recorded lesser percent change in root canal weight than 2Shape. Conclusion: The three file systems were able to prepare severely curved root canals efficiently and safely.