Abstract: A multiple-thread screw includes: a shank having a tapered end portion and a non-tapered portion, the shank defining an axis and a radial plane radiating from the axis; a first spiral thread formed on the non-tapered portion of the shank and having thread turns, each of which has two diametrically disposed points that cooperatively define a diametrical line inclined at a first thread angle with respect to the radial plane; and two second spiral threads formed on the tapered end portion of the shank and twisted in opposite directions. Each of the second spiral threads has thread turns, each of which has two diametrically disposed points that cooperatively define a diametrical line inclined at a second thread angle with respect to the radial plane. The second thread angle is larger than the first thread angle.