The mesial side of the crown is often longer than the distal side, causing the incisai ridge.Although the crown of the mandibular lateral incisor is somewhat longer than that of the central incisor (usually a fraction of a millimeter).there is no marked difference between the mesial and distal surfaces of central and lateral incisors.There is a tendency toward a deeper concavity immediately above the cervical line on the distal surface of the mandibular lateral incisor.including the developmental depressions mesially and distally.7-19, specimen 1).