US Patent 7094056 Endodontic instrument having reversed helix

Methods and apparatus providing an endodontic instrument having a reversed helix. An endodontic instrument in accordance with the invention includes a shaft that includes an end, a tip, one or more flutes, and a longitudinal axis. At least one flute includes a cutting edge configured to cut when the shaft is rotated in a first direction of rotation about the longitudinal axis. The at least one flute spirals around the shaft in an end-to-tip longitudinal direction and in a second direction of rotation that is opposite from the first direction of rotation.