Sevinc Askerbeyli, Selen Küçükkaya Eren, Hacer Aksel, Ahmet Keleş

Effect of Chloroform On the Cyclic Fatigue Resistance of Nickel-Titanium Retreatment Instruments

Background: The purpose of this study was to evaluate the cyclic fatigue resistance of 4 different rotary nickel-titanium (NiTi) retreatment instruments after immersion in chloroform solution. Methods: A total of 120 ProTaper D3, R-Endo R3, D-Race DR2 and Mtwo R2 retreatment instruments were used. Thirty instruments of each system were randomly divided into 2 groups (n=15); Group 1: no immersion and Group 2: immersion in chloroform for 5 min. The instruments were operated in a dynamic cyclic fatigue test device until fracture occurred. The number of cycles to fracture and length of the fractured fragment for each instrument were recorded. Representative samples were examined under a scanning electron microscope. Data were analyzed by using 2-way analysis of variance and Bonferroni tests. Results: The ProTaper D3 and R-Endo R3 instruments showed the highest cyclic fatigue resistance whether or not immersed in chloroform (p0.05). The Mtwo R2 instruments were more resistant to cyclic fatigue than the D- Race DR2 instruments before and after immersed in chloroform (p

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