Dental Anatomy: Maxillary Incisors

Maxillary Incisors

• Their major function is to cut food material during mastication, and they also have phonetic, esthetic, and occlusal functions.

Maxillary Central Incisor

• Erupts between 7-8 years, and root completion occurs around 10 years.
• The widest mesiodistally of any anterior teeth.
• Newly erupted teeth have three rounded features called mamelons on the incisal edges, which disappear with time due to friction.

Labial Aspect

• Relatively straight or slightly curved incisal edge.
• Crown is rectangular and longer incisogingivally than mesiodistally.
• Incisor crown outlines are more convex on the distal than on the mesial surfaces.
• Mesioincisal angles are more acute than distoincisal angles.
• Contact area on mesial surfaces is located in the incisal third, and on the distal surfaces, it is more cervical than the mesial.
• Cervical line curves toward the apex in the middle of the facial surface.
• Root is cone-shaped, with a relatively blunt apex, and is usually 2 or 3 mm longer than the crown.

Lingual Aspect

• Crown has less bulk in the lingual half because the mesial and distal surfaces converge lingually.
• Lingual fossa is a shallow concavity bordered by mesial and distal marginal ridges, and just incisally to the cingulum.
• Root tapers lingually, making the lingual portion of the root narrower than the labial portion.

Mesial Aspect

• Crown is triangular, with the base at the cervix and the apex at the incisal ridge.
• Facial outline is more convex cervically than incisally, and the facial crest of curvature is in the cervical third.
• Lingual outline is convex in the cervical third and the crest of curvature is located on the cingulum, then becomes concave in the middle and incisal thirds.
• Cervical line on the proximal surfaces curves toward the incisal edge.
• Root is cone-shaped with a blunt apex.

Distal Aspect

• The distal outline is similar to the mesial outline, but the curvature of the cervical line is less in extent on the distal than on the mesial surfaces.

Incisal Aspect

• Labial outline is convex but less curved than the more convex lingual outline.
• Outline of the lingual portion tapers lingually toward the cingulum.
• The cingulum of the crown makes up the cervical portion of the lingual surface.
• Incisal ridge may be seen clearly, and a differentiation between the incisal edge and the remainder of the incisal ridge, with its slope toward the lingual, is easily distinguished.

Maxillary Lateral Incisor

• Erupts between 8-9 years, and root completion occurs around 11 years.
• Supplements the central incisor in function, with a crown that bears a close resemblance.
• Smaller in all dimensions except root length.

Principal Identifying Features

• Crown is more rounded, shorter, and narrower mesiodistally than the maxillary central incisor.
• Mesioincisal angle is rounded, and distoincisal angle is more rounded.
• Single root with a tapered distally pointed apex.
• Lingual fossa is more concave than that of the maxillary central incisor.

Labial Aspect

• Smaller crown, narrower cervically.
• Mesioincisal angle is rounder.
• Distal contact is near the middle third.
• Root tip often bends to the distal.
• Incisal edge slopes cervically toward the distal.
• Root length is greater in proportion to its crown length.

Lingual Aspect

• Deep but smaller lingual fossa.
• The cingulum is centered.
• More common lingual pit.

Mesial Aspect

• Root appears longer.
• Crown labiolingually is narrower.
• Curvature of the cervical line is less in depth.

Distal Aspect

• Similar to the mesial aspect, but the curvature of the cervical line is less in depth.
• Sometimes a developmental groove is seen extending along the center of the root.

Incisal Aspect

• Crown is minimally wider mesiodistally than faciolingually.
• Crown outline is more round or oval.
• Cingulum is centered.
• Incisal edge is straighter mesiodistally.

Anatomical Variations

• Peg shape.
• Congenital missing.
• Deep developmental groove distally.