Kazemi RB, Stenman E, Spanberg LS
The endodontic file is a disposable instrument
Journal of Endodontics 21(9):451−5
The cutting efficiency of 7 different brands and types of file rapidly deteriorated when machining dentin
Most cutting and machining tools wear when properly operated on intended substrates. Little is known about endodontic files when machining on human dentin. It was shown earlier that the efficiency of files was very variable when evaluated on Plexiglas substrates. The present study of seven different brands and types of files was undertaken to understand their wear better when machining human dentin. It was shown that all files evaluated rapidly deteriorated when machining dentin. This decline in efficiency was significant but different within, as well as, among brands. It was suggested that endodontic files be disposable.
Morrison SW, Newton CW, Brown Jr CE
The effects of steam sterilization and usage on cutting efficiency of endodontic instruments
Journal of Endodontics 15(9):427−31
The cutting efficiency of files decreased significantly between one and five uses. Sterilisation alone had no effect on cutting efficiency
The effects of steam sterilization and usage on sharpness were evaluated on #25 endodontic files. Files were used to instrument 1, 5, and 10 molars. Control groups determined the effect of steam sterilization alone on cutting efficiency of unused files. A cutting efficiency test was performed on an apparatus that compares sharpness of files when used in linear motion. Scanning electron microscopic analysis was performed in each group. Significant differences were found between experimental files used to instrument 1 molar and those used for 5 or 10 molars. The difference in cutting efficiency between the second and third experimental groups was not significant, indicating that most of the decrease in sharpness occurred with use between one and five molars. No significant difference was found between the control groups, indicating no decrease in cutting efficiency by sterilization alone. The scanning electron microscopic analysis supported the statistical data.