Comparison of two methods for the decontamination of endodontic files

Effective sterilization of all re-usable instruments and disinfection of surfaces within the surgery are key elements of the strategy to minimise potential risk of transmission of infections. For both of these procedures to be effective, thorough cleaning is an essential prerequisite. Objective: To assess residual debris and blood contamination on endodontic files following manual cleaning and autoclaving (method A) or manual cleaning, followed by ultrasonic cleaning and autoclaving (method B). Methods: Ten endodontic files were collected from each of ten general dental practices employing method A and seven practices employing method B. All of the 170 files recovered were visually assessed using a dissecting microscope for residual debris and the presence of residual blood was determined by the Kastle-Meyer technique. Results: Use of either decontamination method resulted in large numbers of files visibly contaminated with residual debris. Only 19% of files using method A (n=100) and 34% of files using method B (n=70) respectively were visibly free of debris. Residual blood contamination of instruments after reprocessing using method A was 7% and method B 9%. Conclusions: This study demonstrates that endodontic files are not reliably decontaminated by methods currently employed in dental practice. This study was supported by the Shirley Glasstone Hughes Memorial Prize Fund from the British Dental Association.