Maxillary protrusion, indicates the protrusion facial figure caused by the over growth of the maxillary bone. In occasion of mandible (jaw) undergrowth the mandible retracts making the upper jaw relatively protruding. This condition is not a real maxillary protrusion. In rare occasion a real maxillary protrusion and mandible undergrowth may coexist. Under this circumstance the upper and lower jaw relationship is not reliable to judge if there is maxillary protrusion exist. Then the relationship between the base of the skull and the maxillary bone is used to make the diagnosis of maxillary protrusion.