A comparison of two reciprocating instruments using bending stress and cyclic fatigue tests

Abstract

The aim of this study was to comparatively evaluate the bending resistance at 45º, the static and dynamic cyclic fatigue life, and the fracture type of the WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 and Reciproc (VDW, Munich, Germany) 25-08 instruments. A total of 60 nickel-titanium (NiTi) instruments (30 Reciproc and 30 WaveOne) from three different lots, each of which was 25 mm in length, were tested. The bending resistance was evaluated through the results of a cantilever-bending test conducted using a universal testing machine. Static and dynamic cyclic fatigue testing was conducted using a custom-made device. For the static and dynamic tests, a cast Ni-Cr-Mo-Ti alloy metal block with an artificial canal measuring 1.77 mm in diameter and 20.00 mm in total length was used. A scanning electron microscope was used to determine the type of fracture. Statistical analyses were performed on the results. The WaveOne instrument was less flexible than the Reciproc (p < 0.05). The Reciproc instrument showed better resistance in the static and dynamic cyclic fatigue tests (p < 0.05). The transverse cross-section and geometry of the instruments were important factors in their resistance to bending and cyclic fracture. Both of the instruments showed ductile-type fracture characteristics. It can be concluded that the Reciproc 25-08 instrument was more resistant to static and dynamic cyclic fatigue than the WaveOne 25-08 instrument, while the WaveOne 25-08 instrument was less flexible. Bending and resistance to cyclic fracture were influenced by the instruments' geometries and transverse cross-sections. Both of the instruments showed ductile-type fracture characteristics.

Noncontact three-dimensional evaluation of surface alterations and wear in NiTi endodontic instruments

“…6 Oxide particles derived from the manufacturing process can act as nucleation sites for the formation of microvoids, leading to dimpled ruptures and subsequent instrument fracture. 13,15,29 In the present study, crack propagation and connected pitted regions were clearly observed in both instruments after the second use, with a greater predominance in the WaveOne instruments (Figure 3a-d). In a previous SEM study, the propagation of cracks parallel to the local fluting orientation under connected pitted regions had been observed on the surfaces of used NiTi instruments.…”

Cyclic fatigue life of Tango-Endo, WaveOne GOLD, and Reciproc NiTi instruments

“…On the contrary with these results, Pedullà et al27 have determined no difference between RPC and WO files. In the studies, the reason for higher cyclic fatigue resistance of RPC files than WO has been shown to be the differences between the cross section and core structures of files 13252829. On the contrary with WO, we believe that WOG files had similar fatigue life values with RPC because of the new alloy and production method of WOG.…”

“…In the literature, there are many studies comparing the cyclic fatigue resistances of WO files, which have been used before WOG files, and RPC files at different angles of curvature 13252627. In their study, Scelza et al25 have compared the cyclic fatigue resistance of RPC and WO files, and found that of RPC to be higher.…”

“…In their study, Scelza et al25 have compared the cyclic fatigue resistance of RPC and WO files, and found that of RPC to be higher. Similarly, in their study on canals having 60° angle of curvature, Arias et al28 have compared RPC files to WO files in terms of cyclic fatigue resistance, and found the cyclic fatigue resistance of RPC files to be higher.…”

Defect propagation in NiTi rotary instruments: a noncontact optical profilometry analysis

“…One hypothesis explaining why flexural fatigue occurs is that the grinding process across the grains of a NiTi wire reduces the overall strength of the instrument, owing to the formation of machining defects along its flute surfaces, and to the build-up of residual stress within its internal structure (Tripi et al 2006). This may be attributed to oxide particles that originate from the manufacturing process and act as nucleation sites for the formation of microvoids, which could lead to dimpled ruptures with subsequent material failure (Kuhn et al 2001, Cheung & Darvell 2007, Kim et al 2012, Scelza et al 2015.…”