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No root fillings were void free. Warm vertical compaction produced a significantly greater volume of gutta-percha and a significantly lower percentage of voids than those achieved with cold lateral compaction. Distribution of sealer and voids within the root canal space after root filling was unpredictable, irrespective of the technique used.

AimTo compare the cyclic fatigue resistance of four reciprocating single‐file systems within artificial stainless‐steel canals at two temperatures using different kinematics.MethodologyA total of 240 instruments, Reciproc Blue, Reciproc, WaveOne Gold and WaveOne, (60 of each), were tested at room and intracanal temperature using both a static and a dynamic model (n = 15) in a stainless‐steel artificial canal with an inner diameter of 1.5 mm, 60° angle of curvature and 5 mm radius of curvature until fracture occurred. The time to fracture was measured in seconds using a digital chronometer, and data were analysed using one‐way analysis of variance and Bonferroni tests.ResultsWaveOne instruments had significantly less fatigue resistance compared to that of other systems in all conditions (P < 0.05). Comparison of the results from the static and dynamic models at both temperatures revealed that fatigue resistance was significantly increased in the dynamic model for all the instrument systems (P < 0.05). Temperature did not influence the cyclic fatigue resistance results (P > 0.05). There were no significant differences in the mean length of the fractured fragments of the various instruments tested (P > 0.05).ConclusionWaveOne files had a shorter cyclic fatigue life. The dynamic axial movement extended the cyclic fatigue life, but it did not have any influence on the comparison among the instruments tested in respect of the static test. Temperature did not significantly affect the cyclic fatigue of these nickel–titanium files.

Filling material left after retreatment procedure may harbour necrotic tissue and bacteria, which could lead to a persistent disease and reinfection of the root canal system. The additional use of self-adjusting file after the conventional retreatment procedures may improve root canal cleanliness, allowing a better action of the irrigating solution.