Machining efficiency of endodontic K files and Hedstrom files.

Methods for the objective evaluation of the machining property of endodontic files were described earlier. These methods were used in this investigation to assess the characteristics of machining of 7 different brands of K files and 10 brands of Hedstrom files. The results show that there are large variations in amounts of material removed by the files. These variations are large between brands of instruments as well as between files of the same brand. Thus, among the 510 files evaluated, the file with the highest machining quality was more than 40 times as effective as the least effective instrument. The highest values among K files were obtained with files manufactured by Maillefer followed by Antaeos, Healthco, JS Dental, Brasseler, and Miltex. Among the Hedstrom files, the most efficient brands were Antaeos and Zipperer followed by Healthco, Hygenic, JS Dental, Miltex, Maillefer, Union Broach, and the least efficient Brasseler. The files did not wear noticeably during these testing procedures. These results clearly indicate that the provider needs more information from the manufacturer in regard to machining and cutting in order to intelligently select instruments. It is suggested that procedures be agreed upon to evaluate machining and cutting of root canal files in order to provide the endodontist with better information about instruments.