Maxillary Permanent Lateral Incisor Overview

Maxillary Permanent Lateral Incisor

• Chronology:

  • Appearance of the dental organ: 5 m.i.u.
  • First evidence of calcification: 1 year
  • Enamel completed: 4-5 years
  • Eruption: 8-9 years
  • Root completed: 11 years

• Type and Function:

  • Function: Incising food and aesthetics.
  • Number of Lobes: Four (three mamelons and cingulum)

• Relation:

  • Contacts the central incisor mesially and the mesial surface of the canine distally.

• No. of Surfaces: Four surfaces and incisal aspect.

• No. of Roots: One root.

• Labial Aspect:

  • Crown Outline: Trapezoid (short side cervically, long side incisally).
  • Outline: Slightly convex mesially, more convex distally, more curved than central incisor, cervical line convex root-wards.
  • Angles: Mesio-incisal angle rounded, disto-incisal angle more rounded

• Surface Anatomy:

  • Surface is more convex than the central incisor.
  • Cervical ridge located at cervical third.

• The Root:

  • Single root, longer than the upper central incisor root.
  • Tapers evenly to apical 1/3, then curves distally with a pointed apex.

• Lingual Aspect: -Same outline as labial aspect -Mesial and distal sides converge lingually, where the lingual surface is narrower than the labial surface. -Convergence accommodates the horseshoe-shaped alveolar process.

• Surface Anatomy Elevations and Depressions:

  • Cingulum (present at cervical 1/3)
  • Marginal ridges (mesial and distal).
  • Incisal ridge.
  • Lingual fossa (lies between previous elevations) -Lingual pit. -Elevations and depressions are more developed than the upper central incisor.

• Mesial Aspect:

  • Outline: Crown is triangular, base cervically, apex incisally; incisal ridge on a line that bisects the root center.
  • Labial outline convex at cervical 1/3 (cervical ridge), then slightly convex to incisal ridge.
  • Lingual outline convex at cervical 1/3 (cingulum), concave at lingual fossa, then slightly convex for incisal ridge.
  • Mesial cervical line convex incisally.
  • Labio-lingual measurement less than the central incisor by approximately 1mm; mesial surface is convex with the maximum convexity at the junction of the incisal and middle 1/3s, (the contact area).
  • Root appears longer than central incisor.
  • Cone shape, blunt apex, developmental depression.

• Distal Aspect:

  • Similar to mesial, but cervical line curvature is less (by 1mm).
  • Contact area located at middle 1/3 (more cervically).
  • Smaller and more convex than mesial.

• Incisal Aspect:

  • May resemble central incisor or a small canine.
  • Labio-lingual dimension is greater compared to the central incisor.
  • Cingulum is centered.

• Pulp Cavity:

  • Mesio-distal Section: Wide, conforming to the crown shape; no three pulp horns (only two).
  • Labio-lingual Section: Chamber pointed incisally, then follows the crown's cervical increase in dimension. -Root canal tapers gradually as it reaches the apex (apical foramen).

• Malformations:

  • Peg-shaped lateral incisor
  • Missing lateral incisor

• Differences between lateral and central incisors: This information is found in a separate question-and-answer section. Four differences are listed and detailed:

  • Size
  • Elevations and depressions
  • Incisal angles
  • Root