Abstract: A method of manufacturing an endodontic instrument using an electrochemical (ECG) grinding process. An instrument blank is formed from stock material, and an electric current is applied between an electrically conductive grinding wheel, acting as a cathode, and the instrument blank, acting as an anode. A continuous stream of electrolyte fluid, a conductive aqueous solution, is applied at an interface between the grinding wheel and the instrument blank, the electrolyte fluid having an associated volume and pressure. The instrument blank is advanced past the electrically conductive grinding wheel to remove material from the instrument blank to form at least one cutting flute. The electric current applied between the grinding wheel and the instrument blank is reduced, and the instrument blank is advanced past the grinding wheel again to form a finish surface, e.g., a sharp cutting edge, on the at least one cutting flute.

Abstract: An endodontic instrument for use in performing root canal therapy on a tooth having at least one straight flute which prevents self-threading or screwing of the instrument into a root canal during use. The instrument includes a shaft having a longitudinal central axis, a shank portion and an elongated working portion extending from the shank portion along the central axis, the elongated working portion having a proximal end, a distal end, and at least one peripheral surface and at least one straight flute formed on at least a portion of the peripheral surface of the working portion, the straight flute forming at least one cutting edge on the peripheral surface. The straight flute may be formed of a plurality of flute sections disposed on the peripheral surface of the instrument, the plurality of flute sections angularly displaced about the central axis with respect to one another. A method of manufacturing an endodontic instrument is also disclosed.

Abstract: Improved endodontic instruments having multiple tapers and instruments which prevent self-feeding or threading into a root canal during root canal therapy on a tooth are provided as well as a process for producing such instruments. The process basically comprises providing a grinding wheel rotated about a first axis having a plurality of flute grinding ribs and an extra flute grinding rib extending from a periphery thereof. A rotating wire stock is fed past the plurality of flute grinding ribs and the extra flute grinding rib at a feed rate and rotation rate such that a separate spiral flute is ground on the wire stock by each of the plurality of flute grinding ribs and the extra grinding rib. The feed rate and rotation rate of the wire stock is changed during the grinding of the instrument whereby the extra grinding rib follows the spiral path of the first flute grinding rib to thereby reduce the number of spiral flutes being ground on the instrument.

Abstract: An improved process for producing an endodontic instrument with a predetermined taper having a plurality of flutes, each with a predetermined number of spirals over a predetermined length of the instrument are provided. The process basically comprises providing a grinding wheel rotated about a first axis having a plurality of flute grinding ribs and a rolled deformed metal grinding rib extending from a periphery thereof. A rotating wire stock is fed past the plurality of flute grinding ribs and the rolled deformed metal grinding rib at a controlled rate along a second axis so that a separate flute is ground on the wire stock by each of the flute grinding ribs and rolled deformed metal is removed from the ground wire stock by the rolled deformed metal grinding rib.