An endodontic file for use in root canal treatment has an elongated shank having a long axis with a proximal end connected to a handle adapted to be manipulated by hand or inserted into a rotary drive. The file also includes a working portion with a plurality of continuous uninterrupted helical spiraled flutes extending to a distal end, the working portion including a plurality of alternating cutting segments and reduced diameter non-cutting segments that are spaced proximally to distally to each other along the working portion. The cutting segments may have reduced diameter non-cutting segments that have continuous uninterrupted helical flutes and associated edges interposed between the flutes. And the flutes and associated edges may pass continuously and uninterrupted between adjacent cutting segment and non-cutting segment. An individual file, or a set of files having the foregoing characteristics but with varying arrangements and/or cross sectional profiles, may be used in an endodontic procedure.