Figure. Measurement of cortical width on panoramic radiographs of subjects with (A) normal cortical shape and width and (B) severely eroded and very narrow cortex. A line parallel to the long axis of the mandible and tangential to the inferior border of the mandible was drawn. A line (dotted line) perpendicular to this tangent, intersecting the inferior border of the mental foramen, was constructed, along which the mandibular cortical width was measured. The distance between the two parallel solid lines is the cortical width. The white arrow shows a mental foramen.