Cyclic fatigue of two different single files with varying kinematics in a simulated double-curved canal.

Abstract

To evaluate and compare the cyclic fatigue of a rotary (One Shape) and reciprocating (Reciproc) single file system in a simulated S-shaped canal in static and dynamic models. The instruments (n=50 per instrument) were tested in a custom-made device under static (n=25) and dynamic loads (n=25) to determine the number of cycles to fracture (NCF). The length of the fractured segments was also measured. Cyclic fatigue data were analyzed by one-way analysis of variance and Tukey honestly significantly different tests, while the data recorded for the fractured fragment lengths were compared using Student's t-test with the level of significance set at 0.05. The fatigue life of Reciproc was significantly higher in the static (coronal curvature: 717.60±45.32 NCF; apical curvature: 621.80±60.15 NCF) and dynamic models (coronal curvature: 972.40±54.30 NCF, apical curvature: 897.70±47.10 NCF) as compared with One Shape (P<0.05). The fatigue life was significantly prolonged in the dynamic model for Reciproc (P<0.05) as compared to One Shape (P>0.05). The results of the present study showed that the single file reciprocating system (Reciproc) had a longer fatigue life than the single file rotary system (One Shape).