Figure 5

CAD geometry model and definition of the screw section: (a) model I, OEM screw; and (b) model II, aftermarket CAD/CAM screw. The letters ‘a’ to ‘f’ denote the head length, neck length, shank length, thread length, thread spacing, and overall screw length, respectively. The letters ‘g’ and ‘h’ denote the angles of the screw hex and thread, respectively.