Screw

A screw comprising:

• a shank including a tapered screw-in portion, a head portion spaced from the screw-in portion along a longitudinal axis of the shank, and a straight rod portion between the screw-in portion and the head portion;
• a first thread helically formed on an outer circumference of the shank and including an upper thread portion formed around the straight rod portion, a lower thread portion formed around the screw-in portion, and a middle thread portion continuously connected between the upper and lower thread portions, with the middle thread portion formed around the straight rod portion adjacent to the screw-in portion, with a lower end of the lower thread portion extending to a tip of the screw-in portion for development of a cutting set point;
• and
• a second thread helically formed on an outer circumference of the screw-in portion of the shank and including a plurality of thread convolutions which are spaced from thread convolutions of the lower thread portion, with a pitch of two adjacent thread convolutions of the second thread being approximately equal to a pitch of two adjacent thread convolutions of the lower thread portion of the first thread.