Cyclic fatigue of profile rotary instruments in relation to their size and diameter

ABSTRACT

The purpose of this in vitro study was to invent a testing device similar to curved canals to investigate the cyclic fatigue of 0.04 and 0.06 Profile system by recording the time lapsed from the beginning of rotation until separation occurred. Revolution number and length of separated pieces were also determined. A metal device was designed and 120 Profile were tested after dividing them randomly into 2 equal groups from size 15-40 of the same taper either 0.04 or 0.06. The result demonstrated that the smaller size significantly resist fracture and take longer time and more revolution to separate when compared to larger sizes. The mean length of separated pieces was significantly longer [P<0.001] and near the end of the cutting section for the Profiles 0.04 when compared to those of 0.06. This may indicate that smaller diameter Profiles considered safer and stronger in clinical practice