Effect of Cleaning and Sterilization Procedures on Niti Rotary Files – An Sem and Eds Study

Abstract

Rotary nickel-titanium files have become the most widely used engine driven endodontic instruments. Whenever these instruments are re-used proper cross-infection control measures should be undertaken. After clinical use if the tenaciously bound debris is not removed from endodontic files, any method of sterlization may be in-effective. Although varying concentration of sodium hypochlorite (NaOCl) have been used to remove the organic debris, its effect on file surface with repeated cleaning and sterlization cycles have not been investigated. The purpose of this study was to assess the effect of repeated cleaning and sterilization procedures on 3 brands of Nickel-Titanium (NiTi) endodontic file using Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS).105 New NiTi instruments from 3 different manufacturers namely ProTaper, RaCe and ENDOWAVE were subjected to 2, 5 and 10 cycles of cleaning and sterilization procedure. Cleaning procedure involved pre soaking of files in 2.5% NaOCl for 15min (Group I) and 1hour (Group II), followed by sterilization process using steam autoclave at 1210C at 15psi pressure for 15minutes. Files were observed for evidence of corrosion such as pitting or deposition of corrosion products using SEM. EDS was conducted to analyze the chemical elements in corroded & non corroded areas of the file. 2.5% NaOCl is much more corrosive when used for 1hr immersion time compared to 15 minutes. All the files showed mild to severe corrosion with 1 hour immersion time in 2.5% NaOCl – ProTaper NiTi files showed most corrosion followed by RaCe and least corrosion in ENDOWAVE rotary files. This can be attributed to various surface treatment included during manufacturing process of these files.