A rotatable endodontic file for cleaning/shaping a tooth root canal, comprising: an elongated shaft having a proximal end portion, a distal end and a tapered working portion having a rotational axis, the working portion extending from said proximal portion to said distal end the external surface of said shaft working portion having a plurality of at least two spirals, a parallelogram-shaped cross section that has an axis of rotation that is asymmetric such that the center of mass (centroid) is not along the file axis.
