UBC Theses and Dissertations
Effect of canal curvature location on the cyclic fatigue resistance of the endosequence controlled memory file Alghamdi, Sarah
Introduction: The study aim was to evaluate the effect of five different root canal curvature locations on the fatigue resistance of thermomechanically treated nickel-titanium (NiTi) files and traditional NiTi files at body temperature. Material and Methods: EndoSequence (ES), EndoSequence (ESCM), K3, K3XF, and Vortex Blue (VB) NiTi files (size 25/.04) were subjected to fatigue testing inside artificial canals with a curvature of 60°, a 3-mm radius, and five different curvatures. Each instrument was rotated until fracture occurred. The number of cycles to failure (Nf) was recorded, the length of the fractured tips was measured, and the fractured surface of the fragments were examined by scanning electron microscopy. The phase transformation behaviour of NiTi files was also examined. Results: ESCM files had the highest fatigue resistance, followed by the VB, K3XF, K3 and ES files (p < 0.05). Among the five curvature locations, ESCM files showed the highest Nf of all the groups (p < 0.05), while either the ES or K3 files had the lowest Nf (p < 0.05). Two endothermic peaks were observed on the heating curve of the heat-treated files (ESCM, K3XF, and VB). Conclusion: The location of the canal curvature had a significant effect on both heat-treated and superelastic NiTi files. Instrumentation of canals with coronal curvature should be cautiously performed.
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