In the mandibular arch, the permanent mandibular lateral incisor is the second tooth from the midline. The mandibular incisor has several unique features. This tooth is wider mesiodistally as compared to the mandibular central incisor. The opposite is true for the maxillary incisors where the maxillary central incisor is larger as compared to the lateral incisor. The mandibular lateral incisor is asymmetrical therefore it is easy to identify right and left mandibular lateral incisors as compared to central incisors that are more symmetrical and therefore difficult to distinguish right incisor from the left.
Development and Emergence of the Permanent Mandibular Lateral Incisor
The calcification of the mandibular lateral incisor begins around the age of 3-4 months. The crown of the tooth is completed by the age of 4-5 years. The mandibular lateral incisor emerges into the oral cavity by the age of 7-8 years. The root of mandibular lateral incisor is completed by the age of 10 years.
Labial Aspect
The permanent mandibular lateral incisor though it resembles the mandibular central incisor. However, it is slightly larger in all dimensions and the crown is asymmetrical. Few developmental lines are present on the labial surface of the tooth and those are not very prominent. The mesioincisal angle is sharp and the distoincisal angle is more rounded.
Lingual Aspect
The tooth slightly converges towards the lingual side. Therefore, part of the mesial and distal surfaces of both the crown and root are visible from the lingual aspect. The tooth sometimes looks similar to the maxillary lateral incisor from this aspect. However, the tooth can be easily differentiated from the maxillary lateral incisor because of its smaller size and less development of marginal ridges.
Mesial Aspect
The mesial aspect of the crown is longer than the distal aspect. The mesial surface of the crown is smooth with no developmental depression. The root has a shallow developmental depression.
Distal Aspect
The distal aspect of the crown is smaller because of the slope of the incisal ridge in a distal direction. Due to this slope of the incisal ridge, the distal contact area is located more towards the cervical area as compared to the mesial contact area. The distal surface of the root has a developmental depression that is more pronounced. The curvature of the cervical line is nearly the same as of the mesial aspect.
Incisal Aspect
The incisal edge of the permanent mandibular lateral incisor is curved and follows the curvature of the dental arch.
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