Cyclic and Torsional Fatigue Resistance of Three Different Thermally Treated Nickel-Titanium Rotary Instruments

Abstract


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

Cyclic and torsional fatigue resistance of a new rotary file on a rotary and reciprocating motion

“…The device has an outer arch with a 1 mm deep groove that guides the instruments' path, keeping them in curvature and allowing them to rotate freely during the tests. This device allowed a precise and reproducible curvature position that was established for all instruments used (Duque et al, 2020;Furlan et al, 2021;Vivan et al, 2022).…”

“…The tests performed were based on ISO 3630-1 (1992) (Alcalde et al, 2018;Alcalde et al, 2020;Vivan et al, 2022).…”