Experimental Validation of Numerical Simulations of a New-Generation NiTi Endodontic File Under Bending

Abstract

The superelasticity of NiTi shape memory alloy has been used in endodontics since the 1990s. To study the mechanical behavior of endodontic instruments, a traditional approach consists in experimental investigations. However, finite element analysis constitutes another way to assess their mechanical behavior and to facilitate their design. The main aim of this study is to compare experimental and numerical bending results on different structures (NiTi wire, spreader, and instruments) to estimate the reliability of the finite element simulations. These investigations were carried out as follows. Firstly, experimental material parameters identification was performed using NiTi wires. These parameters were implemented in an appropriate NiTi model. Bending was numerically applied to the meshed structures generated by the finite element method. Experimental tests were performed on real structures under bending, with exactly the same loading, in order to compare experimental and numerical results. These results were in good agreement for each of the considered structures. This enabled the validation of the simulation results and the use of simulations to design new endodontic instruments.

Modeling the Response of NiTi Endodontic Files Subjected to Cyclic Non‐proportional Loading

“…The complexities associated with the loading and the material behavior invite the application of the finite element method to better understand the mechanical response of endodontic files and improve their design. In previous studies, NiTi endodontic files have been modeled using simplified material models for the cases of bending [2] and realistic boundary conditions, geometries and loadings [3]. Furthermore, complex SMA models have been developed considering secondary features such as functional fatigue [4][5][6], tension-compression asymmetry [7,8], plasticity [9,10] and internal loops [11,12].…”

Combined bending–torsion testing device for characterization of shape memory alloy endodontic files

“…This device allows to apply only bending in consistency with the Standard ISO 3630-1 (2008). The same kind of bending rig is also proposed by Chevalier et al (2018). Fortini et al (2018) designed and realized a test bench for experimental characterization in bending of SMA cantilever beams.…”