Corrosion resistance assessment of nickel-titanium endodontic files with and without heat treatment

Tatiana Dias Costa; Elison da Fonseca E Silva; Paula Liparini Caetano; Marcio José da Silva Campos; Leandro Marques Resende; André Guimarães Machado; Antônio Márcio Resende do Carmo

doi:10.5395/rde.2021.46.e6

Corrosion resistance assessment of nickel-titanium endodontic files with and without heat treatment

Restor Dent Endod. 2020 Dec 28;46(1):e6. doi: 10.5395/rde.2021.46.e6. eCollection 2021 Feb.

Authors

Tatiana Dias Costa¹, Elison da Fonseca E Silva², Paula Liparini Caetano³, Marcio José da Silva Campos³, Leandro Marques Resende⁴, André Guimarães Machado¹, Antônio Márcio Resende do Carmo⁴

Affiliations

¹ Department of Endodontics, Juiz de Fora Estacio University Center, Juiz de Fora, MG, Brazil.
² Department of Metallurgical Engineering, Federal Institute Juiz de Fora, Juiz de Fora, MG, Brazil.
³ Department of Orthodontics, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil.
⁴ Department of Endodontics, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil.

Abstract

Objectives: The aim of this study was to evaluate the corrosion resistance of heat-treated (Reciproc and WaveOne) and non-heat-treated (ProTaper and Mtwo) superelastic nickel-titanium endodontic files when immersed in a 5.25% sodium hypochlorite solution.

Materials and methods: Anodic polarization curves were obtained with potential sweeps that began at the open circuit potential or corrosion potential (E_corr). The pitting potential (E_pit) was identified on the anodic polarization curve as the potential at which a sudden increase in current was observed. The micromorphology of the 28 tested files was analyzed before and after the electrochemical assay using scanning electron microscope (SEM). The data were analyzed using 1-way analysis of variance with the post hoc Bonferroni test (for E_corr) and the Student t-test for independent samples (for E_pit).

Results: The mean E_corr values were 0.506 V for ProTaper, 0.348 V for Mtwo, 0.542 V for Reciproc, and 0.321 V for WaveOne files. Only WaveOne and Protaper files exhibited pitting corrosion, with E_pit values of 0.879 V and 0.904 V, respectively. On the SEM images of the ProTaper and WaveOne files, cavities suggestive of pitting corrosion were detected.

Conclusions: Signs of corrosion were observed in both heat-treated and non-heat-treated files. Of the evaluated files, WaveOne (a heat-treated file) and ProTaper (a non-heat-treated file) exhibited the lowest corrosion resistance.

Keywords: Corrosion; Endodontics; Root Canal.