An endodontic instrument comprises three principal parts: a sleeve-shaped housing (1) one end of which is closed with a nut (2) provided with a straight-through hole； a movable bolt (3) situated axially in the housing (1)； and a replaceable working nosepiece with a coupling attachment (4) to which, at the other end of the housing (1), permanently joined is a cannula (5) with the diameter of 0.30-0.35 mm inside which two thin wires with the diameter of 0.07-1.5 mm are placed to form a loop (6) outside the cannula (5), said wires being joined permanently with each other outside the attachment (4) with the use of a fastener (7). The housing (1) has, on its side surface and in its portion adjacent to the working nosepiece, a longitudinal slit (8) is provided with a width exceeding slightly the thickness of the wire which, on a portion of its length, has a recess (9) with a size exceeding slightly the size of the fastener (7), and the a movable bolt (3), on its working nosepiece side, has a properly shaped groove (10) with a shape analogous to this of the longitudinal slit (8) in the housing (1), in which there are ends of the wire fastened in a fastener (7). The fastener (7) is further situated in a widened portion of the groove (10) provided in the bolt (3) with a screw (11) screwed into opposite side of the bolt (3) for provisional adjustment of position of the bolt (3) with a knob protruding outside the nut (2) screwed onto end portion of the housing (1), whereas there is a spring (13) between the nut (2) and a seat (12) formed on the bolt (3). Side surface of the housing (1) is provided with a longitudinal recess (14) for a screw (15) used to move the bolt (1) manually and thus to draw the wire loop (6), said screw being screwed into a threaded hole provided in the bolt (3) perpendicularly to its axis.
