Permanent Mandibular Central Incisor

Identification

• Position: First tooth from the midline
• FDI Number:
  • Right: 4-1
  • Left: 3-1
• Universal Number: 25 and 24
• Zygmunti-Palmar Number: 1 with quadrant brackets

Function and Development

• Function: Cutting (all incisors)
• Development: From four developmental lobes, shows mamelons when newly erupted

Eruption

• Age of Eruption: 6 to 7 years

Measurements

• Crown Length: 9.5 mm
• Root Length: 12.5 mm
• Mesiodistal Diameter:
  • Crown: 5 mm
  • Cervix: 3.5 mm
• Labiolingual Diameter:
  • Crown: 6 mm
  • Cervix: 5.3 mm
• Curvature of Cervical Line:
  • Mesial side: 3 mm
  • Distal side: 2 mm

Morphological Details by Aspect

Labial Aspect

• Outline Form: Trapezoidal (longer side towards incisal surface)
• Incisal Surface: Horizontal, right angle to long axis
• Angles:
  • Mesioincisal: Sharp
  • Distoincisal: Sharp
• Contact Areas: Both mesial and distal in the incisal third
• Outlines: Straight mesial and distal
• Cervical Line: Convex towards root
• Labial Surface: Smooth, convex with slight flattening in incisal third
• Symmetry: Mesial and distal halves almost symmetrical
• Root: Single, conical, tapering, often distal curvature

Lingual Aspect

• General: Similar outline form as labial aspect
• Surface: Convexities and concavities
• Ridges:
  • Incisal: From mesioincisal to distoincisal angles
  • Mesial Marginal: On mesial border
  • Distal Marginal: On distal border
• Cingulum: At cervical third
• Lingual Fossa: Central concavity among convexities
• Comparison to Maxillary Central Incisor: Less prominent ridges, cingulum, and fossa

Mesial Aspect

• Outline Form: Triangular
• Incisal Ridge: Lingual to midline axis (placing lingual to maxillary incisors)
• Labial Outline: Convex (max. convexity in cervical third, less in incisal third)
• Lingual Outline: Convex (incisal third), concave (middle third), convex (cervical third)
• Root: Labial and lingual outlines taper from middle third to apex, mesial developmental depression in middle third

Distal Aspect

• General: Similar to mesial aspect
• Root: Deeper distal developmental depression

Incisal Aspect

• Visibility: Root not visible
• Diameters: Labiolingual diameter > mesiodistal diameter
• Labial Outline: Smooth, convex
• Lingual Outline: Narrower, showing lingual convergence (feature of all anterior teeth)