Dental burs and endodontic files: are routine sterilization procedures effective?

PURPOSE The complex miniature architecture of dental burs and endodontic files makes precleaning and sterilization difficult. Devising a sterilization protocol for endodontic files and dental burs requires care, and some have suggested that these instruments be considered single-use devices. One purpose of this study was to determine the effectiveness of various sterilization techniques currently used in dentistry for the resterilization of dental burs and endodontic files. The second aim was to determine whether new dental burs and endodontic files, as supplied in packages from the manufacturer, are sterile. MATERIALS AND METHODS The sterility of new (unused) and used dental burs and endodontic files before and after various sterilization procedures was analyzed. New burs and files were tested immediately after removal from manufacturers" packaging, with or without prior sterilization. Burs and files that had been used in various dental offices were precleaned, packaged, resterilized and then tested for various pathogens. Each item was individually removed from the sterilization packaging, transferred by sterile technique into Todd-Hewitt broth, incubated at 37 degrees C for 72 hours and observed for bacterial growth. RESULTS Sterilization procedures were 100% effective for unused burs and unused files but were less than 100% effective for all other test groups. Contamination rates following sterilization ranged from 15% for one group of used burs (p = 0.01) to 58% for one group of used files (p < 0.001). CONCLUSIONS Dental burs and endodontic files, as packaged by the manufacturer, are not sterile and should therefore be sterilized before first use. The resterilization procedures tested here were not adequate, and more rigorous sterilization procedures are needed. If such procedures cannot be devised, these instruments should perhaps be considered single-use devices.