UBC Theses and Dissertations
Effect of canal curvature location on the cyclic fatigue resistance of reciprocating files Sobotkiewicz, Tyler
Objective: The aim of this study was to determine whether the cyclic fatigue resistance (CFR) of WaveOne (WO), WaveOne Gold (WOG), Reciproc (RE), and Reciproc Blue (REB) are affected by the location of the canal’s curvature. The phase transformation behaviors of the reciprocating file systems were also investigated. Methods: The reciprocating files were subjected to CFR testing in five artificial canals with a 60o angle of curvature and a 3 mm radius of curvature. The location of the curvature was unique for each canal. Each file was inserted 16 mm into the canal and operated until fracture occurred. The time to fracture was recorded and the length of the fractured fragment was measured. The surface of the fractured fragment was evaluated with scanning electron microscopy. Differential scanning calorimetry was used to characterize the file’s thermal behavior. Results: Reciprocating files have significantly decreased CFR in canals with middle- and coronally-located curvatures compared to those with apically-located curvatures (p < 0.05). At all tested canal curvature locations, REB had significantly superior CFR compared to WO and RE (p < 0.05). There were no significant differences in CFR between WOG and REB in canals with middle- or coronally-located curvatures (p > 0.05). There were no significant differences in the fractured fragment length between the file systems (p > 0.05) except between WOG and RE in the canal with an orifice to curvature distance of 11 mm (p < 0.05). Surface characterization of the surface of the fractured fragments showed typical patterns of cyclic fatigue failure. Conclusion: The location of the canal curvature had a significant effect on the CFR of the reciprocating files. WOG and REB are more resistant to cyclic fatigue than WO and RE. When heated, WO, WOG, and RE underwent a one-stage phase transformation, while REB underwent a two-stage phase transformation.
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