Cyclic fatigue resistance of reduced-taper nickel-titanium (NiTi)instruments in doubled-curved (S-shaped) canals at body temperature

Abstract

Background. This study was conducted to compare the cyclic fatigue resistance of VDW.ROTATE,TruNatomy Prime, HyFlex CM, and 2Shape nickel-titanium (NiTi) rotary instruments in doublecurvedcanals in a simulated clinical environment. Methods. Eighty NiTi files were used for the fatigue testing in stainless steel canals compatible withinstrument sizes until fracture occurred (n=20): VDW.ROTATE (04./25#), TruNatomy Prime (04./26#),HyFlex CM (04./25#) and 2Shape TS04./25#( 1). For each instrument, the number of cycles to fracture(NCF) was calculated, and the fractured fragment length (FL) was measured. To verify that the fileswere fractured due to cyclic fatigue, the fractured surfaces of the files were evaluated under a scanningelectron microscope. Data were statistically analyzed using the Kruskal–Wallis and Student’s t-tests atthe %95 confidence level. Results. The failure of the files due to cyclic fatigue was first seen in the apical curvature before thecoronal curvature (P<0.05). The highest fatigue resistance was observed in VDW.ROTATE and HyFlexCM files in both curvatures (P<0.05). There were no significant differences in the fatigue resistancebetween the HyFlex CM and VDW.ROTATE files or between the 2Shape and the TruNatomy files(P>0.05). There was no difference in the fractured lengths of the files between the apical and coronalcurvatures (P>0.05). Conclusion. In artificial S-shaped root canals, VDW.ROTATE and HyFlex CM files exhibited higherfatigue resistance compared to 2Shape and TruNatomy files.

Influence of NiTi Wire Diameter on Cyclic and Torsional Fatigue Resistance of Different Heat-Treated Endodontic Instruments

“…NiTi endodontic instruments possess extreme flexibility and strength, even if they are vulnerable to fracture during use in clinical situations [ 2 ]. The main causes leading to fracture of NiTi files are torsional and cyclic fatigue [ 3 ]. Fracture caused by torsional fatigue occurs when the file engages the root canals as the handpiece continues to rotate.…”

“…This last property is connected to the file’s ability to twist before fracture [ 2 ]. Cyclic fatigue occurs when the file rotates freely within the canal, and is exposed to repeated cycles of compression and traction in the part of the root canal with the greatest curvature [ 3 ]. Although both failure modes simultaneously occur in clinical situations, many studies have found that cyclic fatigue fracture is the principal cause of file separation [ 4 ].…”

The Influence of NiTi Alloy on the Cyclic Fatigue Resistance of Endodontic Files

“…Endodontic rotary files have experienced continuous development since nickel–titanium (NiTi) files were introduced in the 1980s [ 1 ]. This alloy improved the flexibility and strength properties of endodontic rotary files compared with conventional stainless-steel endodontic instruments [ 2 ], and it simplified the treatment of root canals by improving the speed, accuracy, and safety of root canal shaping [ 3 ]. Despite continuous enhancements in the design and manufacture of NiTi endodontic rotary files to reduce the occurrence of complications during root canal treatment [ 4 ], failures remain a concern.…”

Apical debris extrusion of full‐sequenced rotary systems in narrow ribbon‐shaped canals

“…VDW ROTATE (VR, VDW, Munich, Germany) is also a newly introduced sequenced file system produced to shape root canal systems preserving pericervical dentin. The design has an S‐shaped, off‐centred cross‐section and constant taper; the file has a special heat treatment to increase flexibility (10).…”

“…VDW ROTATE (VR, VDW, Munich, Germany) is also a newly introduced sequenced file system produced to shape root canal systems preserving pericervical dentin. The design has an S-shaped, off-centred cross-section and constant taper; the file has a special heat treatment to increase flexibility (10). RACE EVO (RE; FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) is a sequenced file system developed by FKG in 2020 for minimally invasive root canal preparation is manufactured from heat-treated NiTi alloy with the electropolished surface and alternate cutting edges with triangular cross-section design (11).…”