Assessment of cyclic fatigue resistance of Protaper Next and WaveOne Gold in different kinematics
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Bulletin of the National Research Centre
(2020) 44:164
RESEARCH
Open Access
Assessment of cyclic fatigue resistance of Protaper Next and WaveOne Gold in different kinematics Amira Galal Ismail1* , Manar Galal1 and Nehal Nabil Roshdy2
Abstract Background: The purpose of the current study was to inspect and compare the influence of applying continuous rotation and reciprocation motions on the cyclic fatigue resistance of Protaper Next (PTN) file (X2) and WaveOne Gold (WOG) Primary file in simulated canals. Twenty Protaper Next files(X2) and 20 WaveOne Gold Primary files were included in this study. A cyclic fatigue testing device was employed to test the cyclic resistance of each file in different motions. The testing device has an artificial custom-made stainless-steel canal with a 60° angle of curvature and a 2-mm radius of curvature. The files were randomly divided into 4 groups; group 1: PTN in continuous rotation, group 2: PTN in reciprocation, group 3: WOG in continuous rotation and group 4: WOG in reciprocation. All the instruments were rotated until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The number of cycles to fracture (NCF) was calculated. The data were analyzed statistically (p < .05). Results: Results represented that when using either continuous rotation motion or reciprocating motion, WOG files showed a significantly longer time until failure than PTN files (p < 0.001). The time till fracture increased significantly, when using both types of files with a reciprocating filing motion. Conclusion: Within the confinement of this study, WOG file in reciprocation showed higher cyclic fatigue resistance than PTN in both continuous rotation and reciprocating motion. The reciprocating motion enhances both files behavior in terms of cyclic fatigue resistance. Keywords: Continuous rotation, Cyclic fatigue ProtaperNext, Reciprocation, WaveOne Gold
Background The behavior of endodontic instruments is considered a critical factor in achieving safe root canal shaping. Nickel titanium (NiTi) rotary instruments showed superiority over stainless steel files in clinical practice. The NiTi instruments provided greater flexibility, super elasticity, and increased cutting efficiency (Peters 2004). However, unexpected instrument fracture may occur during root canal shaping. Rotary NiTi files show two types of failure modes: torsional failure and cyclic fatigue failure. * Correspondence: [email protected] 1 Restorative and Dental Materials Department, National Research Centre (NRC), El Bohouth St., 12622 Dokki, Giza, Egypt Full list of author information is available at the end of the article
Torsional failure takes place when the tip of the file is bound to dentin while its shank is still rotating. Cyclic fatigue occurs when part of the file is bound to dentin while subjected to cycles of compression/tension strain in the area of maximum root canal curvature (Sattapan et al. 2000; Parashos and Messer 2006). Cyclic fatigue is considered the principal cause of
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