US Patent 7435086 Endodontic tool having reduced torque demands

A dental reamer/file is in the form of an elongated shank having a proximal end portion and a distal end and a tapered working portion of determined length extending therebetween, the external surface of the shank working portion having at least two equally spaced apart continuous concave helical flutes and therebetween an equal number of spiraled, spaced apart flanges, each flange having in a plane perpendicular to the length of a longitudinal axis of the shaft an outer end defined by a first and a second surface intersecting at a point of maximum radius from the axis, the first surface being relatively short and the second surface relatively longer, the point of maximum radius providing a spiraled scraping edge.