The permanent Maxillary lateral incisors are the second tooth from the midline. The maxillary lateral incisor performs the cutting function and supplements the permanent maxillary central incisor during mastication and speech. The maxillary lateral incisor bears some resemblance with the maxillary central incisor. The overall dimensions of the maxillary lateral incisor are slightly smaller as compared to the maxillary central incisor.
Development and Eruption of Permanent Maxillary Lateral Incisor
The calcification of the permanent maxillary lateral incisor begins when the child is 10-12 months old. The crown of this tooth is completed by the age of 4-5 years. The tooth emerges into the oral cavity by the age of 8-9 years by replacing the deciduous maxillary lateral incisor and the root is completed by the age of 11 years.
Labial Aspect
The incisal ridge is more rounded as compared to the maxillary central incisor. Similarly, the mesial and the distal incisal angles are also more rounded in comparison with the incisal angles of the permanent maxillary central incisor. The distal incisal angle is more rounded as compared to the mesial incisal angle of the lateral incisor. The mesial outline of the crown is more rounded as compared to the mesial outline of the central incisor. The distal outline of the tooth is even more rounded as compared to a mesial outline of the same tooth and with the distal outline of the central incisor.
In most anatomical forms, the crown of the tooth is more convex in comparison with the maxillary central incisor. The tooth is slightly narrower (2-3mm) mesiodistally and cervicoincisally as compare to the maxillary central incisor. The root length is greater in proportion to the length of the crown. The root is cone shape and in the apical one-third of the root curves in a distal direction and terminate as a pointed root apex.
Lingual Aspect
The mesial and the distal marginal ridges are well developed and the cingulum is also prominent. In between the ridges and the cingulum, a concavity is present called lingual fossa. Due to well-developed ridges and the cingulum, the lingual fossa on the lateral incisor is more concave as compared to the permanent maxillary central incisor. Like the Permanent maxillary central incisor, the crown and the root of the maxillary lateral incisor also tapers towards the lingual aspect. Due to this taper part of the mesial and the distal surfaces of the crown and the root is visible from the lingual aspect.
Mesial Aspect
In the mesial aspect, the crown of the maxillary lateral incisor appears similar to a small central incisor. The crown of the lateral incisor is slightly shorter as compared to the central incisor and the root appears longer. The incisal ridge of the tooth appears thicker as compared to the central incisor. The curvature of the cervical line is towards the incisor ridge.
Distal Aspect
The labiolingual width of the crown is slightly more on the distal aspect because of the curvature of the crown portion of the tooth. The curvature of the cervical line is also towards the incisal ridge but the extent of the curvature is less as compared to the mesial surface. A developmental groove is present on the distal surface of the root.
Incisal Aspect
In the dental arch, the tooth is positioned in between the maxillary central incisor and the canine. Therefore, the tooth sometimes resembles the central incisor and canine. The labiolingual dimension of the tooth is greater as compared to the mesiodistal dimension. From the incisal aspect of the tooth, it appears more convex with more rounded surfaces as compared to the central incisor.
Variation and Anomalies
After the third molars which are the most variable teeth. The maxillary lateral incisors are the second most variable tooth in the dental arch. One of the most common anomalies associated with this tooth is a smaller than usual and pointed tooth called the peg shape lateral incisor. In some cases, the maxillary lateral incisors are congenitally (by birth) missing. In this case, the permanent maxillary central incisors are in contact with the maxillary canines. An additional developmental groove is presently extending from the cingulum to the root surface. Sometimes instead of the cingulum which is a rounded convexity, a large pointed structure called tubercle is present.
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