Instrument for drilling dental root canals comprising a sharp rod (1) that has at least a part of its length, called an active part (1b), a polygonal section (4) that forms at least two cutting edges (5a, 5b ； 52, 54), said active part (1b) ends in a tip (3) and is delimited by a cylindrical or conical envelope (7) whose longitudinal axis coincides with the axis of rotation (R) of the instrument, said part active (1b) comprises a first portion (1c) extending from the tip (3) and a second portion (1d) extending after the first portion (1c) towards the back of the active part (1b) The instrument is characterized in that any section (4a； 4'a； 40a) of the first portion (1c) has a center of mass (ma； m'a； m40a) located on the axis of rotation (R) and because said at least two cutting edges (5a, 5b； 52, 54) defined by said section (4a； 4'a； 40a) are in the wrapper ura (7)； and by the fact that at least one section (4b； 4'b； 401b) of the second portion (1d) has a center of mass (mb； m'b； m401b) displaced with respect to the axis of rotation (R) and at least one cutting edge (5a； 52, 54) defined by said section (4b； 4'b； 401b) is located far inside the envelope (7).Instrumento para perforar los canales radiculares dentales que comprende una varilla afilada (1) que presenta en al menos una parte de su longitud, denominada parte activa (1b), una sección poligonal (4) que forma al menos dos bordes cortantes (5a, 5b ； 52, 54), dicha parte activa (1b) termina en una punta (3) y está delimitada por una envoltura (7) de forma cilíndrica o cónica cuyo eje longitudinal coincide con el eje de rotación (R) del instrumento, dicha parte activa (1b) comprende una primera porción (1c) que se extiende desde la punta (3) y una segunda porción (1d) que se extiende a continuación de la primera porción (1c) hacia la parte posterior de la parte activa (1b), el instrumento se caracteriza porque cualquier sección (4a； 4'a； 40a) de la primera porción (1c) tiene un centro de masa (ma；m'a； m40a) sit
