The effect of NaOCl treatment and sterilization procedures on the corrosion of endodontic files

Article information

Restor Dent Endod. 2005;30(2):121-127

Publication date (electronic) : 2005 March 31

doi : https://doi.org/10.5395/JKACD.2005.30.2.121

Won-Kyung Yang ¹, Yoon-Sik Ra ¹, Young-Kyoo Lee ², Ho-Hyun Son ³, Mi-Ri Kim ¹

¹Department of Conservative Dentistry, Department of Dentistry, Asan Medical Center, Korea.

²Department of Periodontics, Department of Dentistry, Asan Medical Center, Korea.

³Department of Conservative Dentistry, College of Dentistry, Seoul National University, Korea.

Corresponding author: Mi-Ri Kim. Department of Conservative Dentistry, Department of Dentistry, Asan Medical Center, 388-1, Poongnap-dong, Songpa-gu, Seoul, Korea, 138-736. Tel: 82-2-3010-3824, Fax: 82-2-3010-6967, kmr333@unitel.co.kr

Received 2004 August 30; Revised 2004 October 28; Accepted 2004 November 09.

Abstract

A variety files made of stainless steel (S-S) or nickel-titanium (Ni-Ti) are used during endodontic treatment. The purpose of this study was to evaluate the corrosion susceptibility of S-S and Ni-Ti endodontic files. Three brands of files were used for this study: K-flex® S-S files (Maillefer, USA), Profile® Ni-Ti files (Maillefer, USA), K-3® Ni-Ti files (SybronEndo, USA). 120 files of each brands (21mm, ISO size #20) were divided into 12 groups according to 1) sterilization methods using Autoclave or Ethylene Oxide (E-O) gas, 2) Irrigation solutions using 5.25 % NaOCl or Saline, 3) the number of sterilization (1, 5, 10 times). After above procedures, each of the files was inspected by three examiners with a light microscope and camera at X25. Each file was judged and ranked according to the following criteria: 0; no corrosion, 1; mild corrosion, 2; moderate corrosion, and 3; severe corrosion. The files of high score were examined under the Scanning Electron Microscope.

Data were statistically analyzed with the Kruskal-Wallis test (p < 0.05). Most of the ten time-autoclaved files had showed mild to moderate corrosion. But, one or five time-autoclaved files did not show corrosive surface. NaOCl treatment and E-O gas sterilization did not influence on corrosion. There was a significant difference in corrosion susceptibility between sterilization methods and the number of autoclaving. However, there was no significant difference between brands and file materials.

Keywords: K-flex® file; Profile®; K-3® file; Autoclave; Ethylene Oxide gas sterilization; NaOCl; Corrosion

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This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Figure 1

Low magnification of untreated K-flex® file, Profile®, and K-3® file (SEM photo).

Figure 2

SEM photographs of K-flex® file treated with sodium hypochlorite and autoclaved ten-times (left arrow; fissure line, right arrows; pitting).

Figure 3

Low magnification (left) and high magnification (right) of Profile® treated with sodium hypochlorite and autoclaved ten-times (arrow; pitting)

Figure 4

Low magnification (left) and high magnification (right) of K-3® file treated with sodium hypochlorite and autoclaved ten-times (arrows; pitting).

Figure 5

Sum of corrosion scores of autoclaved files (O; NaOCl, X; Saline).

Ten times-autoclaved files had significantly different from one or five times-autocaved files (p < 0.05). There was no significant difference between brands and file materials.

Figure 6

Sum of corrosion scores of E-O gas sterilized files (O; NaOCl, X; Saline).

EO-gas sterilized files did not showed significantly different from each other (p < 0.05). There was no significant difference between brands and file materials.

Table 1

Classification of the experimental groups. The files in each group were immersed in 5.25% sodium hypochlorite or normal saline for 10 minutes before sterilization (36 groups, n = 10 / group).