Torque range, a new parameter to evaluate new and used instrument safety
The aim of the present study is to evaluate operative torque, torque at failure and the difference between these two values-the "torque range"-of two different NiTi files. We also sought to evaluate and compare these parameters for new and used files. Forty S-One 20.06 and forty M-Two 20.06 were tested, divided in four equal groups (n = 10) for each brand. Ten instruments from each brand performed three root canal treatments each on standardized extracted single-rooted teeth. Afterwards, each group was subjected to the following two tests: operative torque and torsional resistance.