Features of permanent maxillage central incisor and lateral incisor are very similar, which makes it important to know even the smallest of difference between the two teeth. Starting with some general features, central incisor is the first tooth from the midline and lateral incisor is the second. This gives the two teeth different tooth numbers in various tooth notation systems. Chronologically, lateral incisor erupts just around 1 to 2 years after the eruption of central incisor. If we take a look at their measurements, we see that the crown of lateral incisor is smaller than central incisor in all dimensions. Though the crown is smaller, the root length is same. This makes the relative length of root to crown more in lateral incisor than central incisor. Now, let us study the morphological differences in detail. Labial aspect Both incisors are similar in having crown with trapezoidal outline forms. But the incisal ridge is horizontal in central incisor whereas it is curved in lateral incisor. The mesioincisal angle is sharp in central incisor but it is slightly rounded in lateral incisor. And the distoincisal angle is rounded in central but is even more rounded in lateral incisor. Both contact areas of lateral incisor are cervical to that in the central incisor. The mesial contact area in the central incisor is in the incisal third and in lateral incisor is at the junction of incisal and middle third and the distal contact area in central incisor is at the junction of incisal and middle third whereas in lateral incisor it is in the middle third. The mesial outline is straight in central incisor and slightly convex in lateral whereas the distal outline is slightly convex in central incisor and it is even more convex in lateral incisor. The labial surface of the crown is convex in both the teeth, but it is more convex in lateral incisor. Both incisors have a single conical root, but the mesodistal diameter of lateral incisor is less due to which it appears more slender. Moreover, the tip or apex of the root very commonly shows a distal tilt in the lateral incisor. Lingual aspect. The differences in outline form from the labial aspect are same from the lingual aspect too. Coming to the surfaces, all the three ridges, incisal ridge, mesial marginal ridge and distal marginal ridge are more prominent in lateral incisor than central incisor. Also, the cingulum is more convex and well developed in lateral than central incisor. The lingual fossa is shallow in central incisor but is deep and well demarcated in lateral incisor. Moreover, it is W shaped in central incisor but not in lateral incisor. There it is more of V shaped. Also, the lingual fossa in central incisor does not have any developmental groove or pit whereas they are very common in lateral incisor. Additionally, many times a groove is seen running from the distal side of the cingulum crossing the cervical line and running on to the root called the palatoradicular groove and palatogingival groove. Mesial aspect Both teeth are similar in having a triangular shape and the incisal ridge being on the midline axis. From the mesial aspect, the labial outline of the crown in both incisors is convex but is less convex in lateral incisor. though the crest of contour is still at the same level. The labiolingual width of the crown at the incisal third appears greater in lateral incisor. This is because of the more prominent incisal and marginal ridges. Distal aspect. The difference observed from the mesial aspect are seen from the distal aspect as well. Additionally, the already mentioned pallet-to-radicular or pallet-to-gingival groove if present is also seen from the distal side. Incisal aspect, the outline form of the central incisors is triangular but in lateral incisors is ovoid. Now this is because of the difference between the labiolingual and mesodistal diameters of the two incisors. In central incisor, the difference is 1.5 mm whereas in lateral incisor it is only 0.5 Apart from all these differences, lateral incisors shows a lot of developmental variations not seen in central incisors. The crown shape of lateral incisor varies in its form more than any other tooth in the mouth except the third molar. For example, commonly it appears like a conical tubercle known as the peg lateral. Lateral incisors are one of the most commonly seen congenitally missing teeth in the mouth second only to third molars.