The occlusion is determined by the placement of upper and lower jaws. In a normal occlusion, the lower front teeth should touch the inner surface of upper front teeth. One-third of the outer surface of lower front teeth should be covered by upper front teeth. The outer surface of lower front teeth should be 2mm to 4mm apart from the inner surface of upper front teeth.

If the upper jaw bone is too big when compared with the lower jaw bone, it results in 'projected upper teeth'.