A SEM evaluation of debris removal from endodontic files after cleaning and steam sterilization procedures

Background: In recent times, it has been proposed to classify endodontic files as single‐use items due to a perceived inability to adequately clean the instruments. The purpose of the present study was to quantify the surface debris on files removed from the manufacturer's packaging, and after cleaning using an ultrasonic bath or a thermal disinfector. Methods: Stainless steel and rotary nickel‐titanium files were examined after removal from the manufacturer's packaging, after instrumentation in broth‐contaminated human teeth, and after various cleaning procedures. The cleaning procedures consisted of either a thermal disinfector cycle, ultrasonication with the files placed in a perforated container or ultrasonication with the files loosely placed in a beaker. The presence of manufacturing debris and biological debris was evaluated using scanning electron microscopy and quantified using image analysis software. Results: The effectiveness of cleaning was not affected by variation in the size or taper of the files when an effective cleaning procedure was used. Cleaning the files in a thermal disinfector or by ultrasonication within a container did not consistently achieve complete removal of biological debris. Placing the files loosely in the ultrasonic bath achieved the most effective cleaning, an average of 98.33 per cent of the file surface area was freed of any biological debris. Conclusions: A conventional cleaning method is capable of effectively removing biological debris from endodontic files. The efficacy of ultrasonic cleaning was impaired when the files were placed within a perforated container.