The Effectiveness of Three Different Methods for Sterilization of the Endodontic Files (An in Vitro Study)

Background : Sterilization is the procedure by which all the vegetative or sport state microorganisms’ threats are countered. The main aim of sterilization in the health care field is to eradicate the spread of existing infectious diseases and preventing any new infections. In dentistry, it primarily relates to reuse of instruments to prevent cross-infection and ensure optimal dental care. The complex miniature architecture of endodontic files makes cleaning and sterilization difficult, and some professionals have suggested single use for these instruments. Aim: The purpose of this study was to compare the effectiveness of different methods of sterilization for endodontic instruments: Autoclaving without a plastic bag, Autoclaving with a plastic bag, CO 2 laser, Diode laser, and Glass- bead sterilization. Material and Methods : The study was performed on 60 endodontic K-files, 21 mm long and size 5o, divided into 6 groups, 10 for each, the first group were considered as control. The files contaminated with a homogenous spore suspension of Bacillus thuringiensis . Then, the contaminated files of the 6 groups sterilized by different sterilization methods: Autoclave, Autoclave with a plastic bag, glass-bead, Diode laser, and CO 2 laser. The sterilized files washed in 5ml of normal saline and then 0.1ml suspended solution powered in 8cm Petridis of nutrient agar and number of well isolated colonies were counted after 24 hours of incubation at 37 ºC. Results : The study showed that the files sterilized by autoclave were 99.66 % sterile, while with a plastic bag give a 99.32 %sterile. Those sterilized by glass-bead were96.74 % sterile and those with CO 2 laser were 93.85 %, and diode lasers were 84.24 % sterile. Statistical analysis of all sterilized groups showed a statistical significant difference between groups regarding their sterilization efficiency. Comparison of the sterilized groups with the control group about their efficacies in sterilization showed that the difference was statistically significant. Conclusion : Autoclave, with or without bag, is considered the best sterilizing technique. To achieve one hundred percent of sterilization the time of autoclave must be suitable to allow the killing of all microorganisms. For faster sterilization other methods could be used but with less effectiveness. Aim: The aim of this study was to investigate the efficacy of three methods for sterilization of endodontic instruments: Autoclaving (with plastic bags and without), laser sterilization (CO 2 and diode laser) and glass-bead sterilization.