Cleaning endodontic files in a washer disinfector

Key Points Washer disinfectors are becoming more commonly used in general dental practice. This work was designed to see if washer disinfectors could cope with the difficult challenge of cleaning small instruments with a complex surface structure. Although the files treated in the washer disinfector were generally clean, they were not totally free of organic debris. This work reinforces the view that endodontic files should be single-use only. Aims The aim of this study was to compare the cleanliness of endodontic files that had been cleaned in a washer disinfector according to the file holding mechanism within the machine. Methodology Selected canals of extracted teeth were filed with new, unused files. One set of files (size 15 to 40) was used for each canal. A total of 192 files were used for cleaning and shaping. The files were divided into three groups. The first group was a control group containing 30 files, which were not cleaned in the washer disinfector. The second and the third groups were the experimental groups with 81 files in each group. These files were cleaned in the washer disinfector using different holding mechanisms (file holder or cleaning basket) for each group. The files were examined for visible debris under a light microscope at x45 magnification. Results None of the 162 cleaned files were totally free of organic debris. Comparison of the debris scores in the two experimental groups showed that the files in the cleaning basket group were significantly cleaner than those in the file holder group. The files in both test groups were significantly cleaner than those in the control group. Conclusions Endodontic files cannot be totally cleaned using a washer disinfector alone. The instrument holding mechanism within the machine has a significant effect on the cleanliness of the files after one intensive cleaning cycle.