Comparison of nickel-titanium file distortion using electric and air-driven handpieces

The use of rotary instrumentation has increased dramatically in endodontics , Air-driven and electric handpieces are both currently available for use w ith the nickel-titanium files. To date no studies have compared the frequen cy of instrument separation and/or distortion while using the two types of handpieces with rotary files. The purpose of this study was to determine wh ether there is a difference in the frequency of file separation/distortion when an electric handpiece is compared with an air-driven handpiece, Extrac ted human molar teeth were instrumented with nickel-titanium Profile ISO .0 4 taper rotary files (Dentsply Tulsa Dental Products, Tulsa, OK) under cont rolled conditions and the results examined for statistical significance. Th e teeth chosen for the study fit the following criteria: minimal caries, cu rvature of any root no greater than 60 degrees and at least one root with a minimum of 30-degree curvature, The air-driven handpiece was used at 167.6 7 rpm and the electric handpiece at 150 rpm per manufacturer's recommendati ons. Files were examined both before and after use to evaluate whether brea kage or deformation had occurred. There was no significant difference in fi le breakage or distortion when the handpieces were compared. There were, ho wever, a significantly greater number of file separations/distortions noted in the #8 Profiles (ISO size 20) than with the other files, It may be prud ent to view this file as a disposable instrument.