| 摘要 |
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 centered such that the cross section center of mass (centroid) is located at the axis of rotation where the acute angle of the parallelogram is different along the length of the file. |
