J Korean Acad Conserv Dent.  2005 Mar;30(2):121-127. 10.5395/JKACD.2005.30.2.121.

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

• Yang WK
• Ra YS
• Lee YK
• Son HH
• Kim MR

• KMID: 1987004
• DOI: http://doi.org/10.5395/JKACD.2005.30.2.121

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(R) S-S files (Maillefer, USA), Profile(R) Ni-Ti files (Maillefer, USA), K-3(R) 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.

Keyword

K-flex(R) file; Profile(R); K-3(R) file; Autoclave; Ethylene Oxide gas sterilization; NaOCl; Corrosion

MeSH Terms

Corrosion*
Ethylene Oxide
Stainless Steel
Sterilization*
Ethylene Oxide
Stainless Steel

Figure

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  Figure 1 Low magnification of untreated K-flex® file, Profile®, and K-3® file (SEM photo).

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  Figure 2 SEM photographs of K-flex® file treated with sodium hypochlorite and autoclaved ten-times (left arrow; fissure line, right arrows; pitting).

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  Figure 3 Low magnification (left) and high magnification (right) of Profile® treated with sodium hypochlorite and autoclaved ten-times (arrow; pitting)

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  Figure 4 Low magnification (left) and high magnification (right) of K-3® file treated with sodium hypochlorite and autoclaved ten-times (arrows; pitting).

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  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.

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  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.

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