Evaluation of Flexibility, Microstructure and Elemental Analysis of Some Contemporary Nickel-Titanium Rotary Instruments

Abstract

BACKGROUND: Contemporary nickel-titanium (NiTi) rotary endodontic instruments had a revolutionary impact on the success of root canal treatment.
 AIM: To evaluate the flexibility, microstructure and elemental analysis of four different recent NiTi rotary instruments, namely; Wave One Gold, TF adaptive, HyFlex EDM and Gr_Reciproc Blue compared to conventional Protaper Universal (F2).
 MATERIAL AND METHODS: The NiTi rotary files were subjected to cantilever bending test to evaluate their flexibility. The microstructural characteristics and elemental analysis were examined via scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDX).
 RESULTS: The TF adaptive, HyFlex EDM and Wave One Gold endodontic files showed significantly lower cantilever bending values (i.e., higher flexibility) than Protaper F2 and Gr_Reciproc Blue (p < 0.05). The SEM micrographs showed that the bulk of all examined files showed multiple striations due to the cutting process, on the other hand, their external surfaces were different: The Protaper Universal F2 showed multiple voids, while the TF Adaptive surface exhibited more uniform structure. The Hyflex EDM had a crater-like surface, whereas Wave one Gold showed machining grooves with minimum defects, while Reciproc Blue displayed machining grooves with random scratch lines. There was a significant difference in bulk and surface elemental analysis of the various examined files, yet composed mainly of the same elements.
 CONCLUSION: Chemical composition, heat treatment, manufacturing process and geometrical design of the NiTi rotary instrument have a great influence on their flexibility and microstructure.

Role of the Crystallographic Phase of NiTi Rotary Instruments in Determining Their Torsional Resistance during Different Bending Conditions

“…Despite this, only recently has attention been focused on the combined interaction of these two phenomena [ 16 ]. Previously, there was a tendency to consider flexural and torsional stresses as two distinct factors, not considering their reciprocal influence [ 18 , 19 , 20 , 21 , 22 ]. Nevertheless, first Seracchiani et al recently demonstrated the relationship between the torsional resistance of NiTi rotary instruments and the bending moment acting on them, stating that when increasing the flexural loading, the torsional resistance of the bent instruments increases as well.…”

Análisis Elemental de las Propiedades Morfológicas, Físicas y Químicas de Dos Instrumentos Rotatorios Protaper Universal

“…En la Figura 1C se observan algunas líneas sobre la superficie del instrumento (Purayil et al, 2018;Gavini et al, 2018). Sin embargo, al comparar mediante el análisis de EDX el porcentaje de NiTi de ambos grupos, no se observó una diferencia estadísticamente significativa (p > 0.05) lo cual nos hace suponer que a pesar de que los instrumentos no pasaron por el mismo control de calidad en cuanto al pulido, la composición es muy similar entre ambos grupos (Hamdy et al, 2019).…”

Relation between laboratory cantilever bending test and finite element analysis of five different nickel-titanium rotary instruments

“…This finding may be attributed to the metallurgical composition of the file which is based in their fabrication on the transformation of austenite NiTi wire into the Rphase by thermal procedure (De Arruda Santos et al 2013). Moreover, the twisting of the file give a unique shape that improve file flexibility (Walid 2017;Hamdy et al 2019).…”

“…Moreover, it influences the possibility of endodontic file separation (Fukumori et al 2018). Modifications of the flexibility of the NiTi endodontic rotary instruments depend greatly on their metallurgical composition, fabrication procedure, manufacturing treatment, and geometrical design (He and Ni 2010;Hamdy et al 2019;Galal and Hamdy 2020). Cantilever bending test is the most frequently used test to evaluate the flexibility of the endodontic rotary instruments (Fukumori et al 2018).…”