Physical Properties of Modern Reciprocal Endodontic Systems and Fatigue Failure Testing in Simulated Clinical Conditions

Abstract

Instrument fracture ranks among the most crucial complications during the endodontic treatment of a tooth. In order to better understand the practical limits of the instrument, the relation between the cyclic fatigue resistance and physical properties such as hardness, modulus of elasticity, creep and surface roughness were explored. Cyclic fatigue testing in an artificial root canal at intracanal temperature, nanoindentation and 3D microscopy were used for evaluation of four commonly used thermomechanically treated NiTi endodontic instruments (Unicone Plus 6/025, Unicone 6/025, Reciproc Blue R25 and WaveOne Gold Primary). Cyclic fatigue results were analyzed using the Kruskal–Wallis, Mann–Whitney and Bonferroni corrections. The wear resistance of Unicone 6/025 instruments was significantly lower compared to all other instruments (p < 0.05). WaveOne Gold Primary was significantly less resistant than Unicone Plus 6/025 and Reciproc Blue R25, while the difference between Reciproc Blue R25 and Unicone Plus 6/025 was insignificant (p > 0.05). These results are in correlation with measurements of local mechanical properties (hardness, elastic modulus and their ratios H/E and H3/E2). Even though surface roughness, area of cross-section and shape of instruments are important factors affecting instruments behavior, thermal processing appears to be the most important.

An Examination of the Impact of Blue Heat Treatment on the Forced Caused by the Vertical Motion of Endodontic Files

“…Due to the fact that the examined files employ the reciprocating-movement technique, the present investigation did not investigate the torque exerted. Attempts were undertaken in the current investigation to ensure comparability of the experimental groups despite variances in the morphology of natural teeth 24 . Straight canals were included to remove the effect of the inclination of force vectors, which could impair the accuracy of the measurements, and constricted canals were chosen for this study and confirmed to give extra challenges for the canal shaping (39).…”