Cyclic fatigue, torsional resistance, and angular deflection of two heat-treated files: M-wire versus new F-wire technology

The cyclic fatigue, torsional resistance, and angular deflection of a new Fire-Wire rotary file (CricENDO) were compared. A total of 20 files of each type were tested. Cyclic fatigue testing was performed for each group (n = 10) by measuring the number of cycles to fracture (NCF) in an artificial stainless-steel canal (60° angle of curvature, with a 6-mm radius) for each group. The torque and angle of rotation at the failure of each group (n = 10) were measured according to ISO 3630-1. The fractured surfaces were examined using scanning electron microscopy. Statistical analysis was carried out utilizing Student's t-test at a significance level set at 5%. The Fire-Wire CricENDO rotary files were associated with a significantly higher number of cycles to fracture and time to failure (in seconds) compared to the M-Wire Protaper Next (p < 0.05). A significantly higher angular deflection to fracture was observed for CricENDO compared to Protaper Next (p < 0.05). The new Fire-Wire CricENDO rotary files exhibit higher cyclic fatigue resistance and angle of rotation to fracture than M-Wire Protaper Next. Without warning, file fracture may occur as a result of cyclic fatigue, torsional stress, or a combined effect of both. CricENDO rotary files may be an effective alternative in curved root canals as they exhibited elevated cyclic and torsional resistance. It will be helpful in eliminating one of the reasons for file fracture during the root canal treatment.