External Morphology Maxillary Lateral Incisor

Facial view

The mesial and distal crests of curvatures are at different levels as the mesial surface contacts the distal of the central incisor and the distal surface is in contact with the mesial surface of the canine. The outline of the crown is a series of curves. The distal outline of crown is more convex than the mesial outline and both of these outlines are more convex than the maxillary central incisor. The crown has an incisal ridge which is convex from mesial to distal and is more convex compared to the maxillary central incisor. Two basic crown shapes exist; one is wide M-D at the cervix (square crown form) and the other is narrow M-D at the cervix (tapered crown form). The cervical line is convex in this view.

Mesial Outline of Crown

The mesial outline of the crown is convex. The mesial crest of curvature is at the junction of the incisal and middle third of the crown.

Distal Outline of Crown

The distal outline is more convex than the mesial outline of the crown and the distal crest of curvature is in the middle third of the crown.

Incisal Ridge

With wear, the incisal ridge becomes an incisal edge. The incisal ridge is curved mesiodistally.

Labial Surface of Crown

Three convexities are visible on the labial surface that demarcate the three labial lobes. There is generally more cervical taper mesiodistally compared to the maxillary central incisor.

Root

The root is cone-shaped and convex on its labial surface. There is a conical shape to the root which has greater taper in the apical half compared to the cervical half of the root. Overall, the root is usually about 1.5X longer than the crown. There is often a curvature of the apex to the distal but this is variable.