CYCLIC AND TORSIONAL FATIGUE RESISTANCE OF THREE DIFFERENT THERMALLY TREATED NICKEL-TITANIUM ROTARY INSTRUMENTS


 Background: The aim of this study was to evaluate the cyclic fatigue and torsional resistance three thermally treated rotary instruments, such as: Logic 2 25.05 (LOG 25.05), Edge Taper Platinum 25.06 (EDT 25.06) ProTaper Gold 25.08 (PTG 25.08).Methods: A total 60 instruments LOG 25.05, EDT PTG were used (n=20). Cyclic tests performed at 36°C using an artificial stainless steel canal with a 60o angle 5-mm radius curvature. time (in seconds) number cycles fracture (NCF) recorded. test evaluated torque rotation failure 3 mm from tip according ISO 3630-1. fractured surface each fragment observed by scanning electron microscopy (SEM). Data analyzed one-way ANOVA Holm-Sidak’s for multiple comparison, level significance set 5%.
 Results: had highest (time NFC), followed (P<0.05). There no significantly difference between ETP regarding NCF (P>0.05). In relation test, presented similar greater than other groups lowest angular SEM images demonstrated typical features fracture.