1. The lower inclined
plane caps the lower incisors and is inclined at about 450 to the
occlusal plane. On closing the upper incisors, which formerly occlude
behind the lower incisors , bite on the inclined plane and the pressure
of the bite (P) divides into two force vectors P1 and P2(Figure 1). The
pressure (P1) proclines the upper incisors. The Pressure (P2) intrudes
the incisors. The steeper the plane the greater the forward pressure on
the maxillary incisors. The advisable angle is 45° [p]