Cyclic fatigue of Profile rotary instruments after clinical use

Aim The purpose of this study was to evaluate cyclic fatigue of .06 Profile Ni-Ti rotary instruments after clinical use in molar teeth. Methodology In group 1, instruments size 40-15 were used in a crown-down te chnique using 2.5% NaOCl as an irrigant. Fifty-two molars were included and 13 sets of Profile Ni-Ti rotary instruments were used. Each set of instrum ents was used in four molars. and was steam autoclaved before each use. Gro up 2 (10 sets of new Profile Ni-TI rotary instruments) was the control grou p, Cyclic fatigue was tested by rotating the instruments in a 90 degrees me tallic tube until they broke. Results One-way analysis of variance did not show any statistically signifi cant differences amongst the files from both groups regarding cyclic fatigu e. Conclusions II was concluded that sterilization and clinical use in the pre sence of NaOCl did not lead to a decrease in the number of rotations to bre akage of the files.