Maxillary Central Incisor

Incisal Dominance

• First tooth from the midline
• Most prominent effect on a person's smile
• Referred to as incisal dominance

Tooth Numbering Systems

• FDI System: 1 1 and 2 1
• Universal System: 8 and 9
• Zygmunti-Palmer System: 1 (right and left, different brackets for quadrant)

Function

• Cutting

Developmental Lobes

• Develops from four lobes: mesial, labial, distal, lingual
• Labial Aspect: Formed by mesial, labial, distal lobes
• Lingual Aspect: Formed by less developed lingual lobe (cingulum)
• Mammulons: Three protuberances on incisal ridge in newly erupted incisors, wear off with use

Age of Eruption

• 7 to 8 years

Measurements

• Crown length: 10.5 mm
• Root length: 13 mm
• Mesiodistal diameter: 8.5 mm at contact areas, 7 mm at cervix/root junction
• Labiolingual diameter: 7 mm at cingulum, 6 mm at cervix
• Cervical line curvature: 3.5 mm on mesial side, 2.5 mm on distal side

Morphology (5 Aspects)

1. Labial Aspect

• Crown outline: trapezoidal
• Incisal surface: horizontal, ends at mesioincisal (sharp) and distoincisal (rounded) angles
• Contact areas: Mesial (incisal third), Distal (junction of incisal/middle third)
• Crown surface: smooth and convex, slight mesial/distal depressions
• Root: smooth, convex, tapering

2. Palatal Aspect

• Narrower than labial surface
• Similar features with different surface details
• Ridges on surface: Incisal, mesial marginal, distal marginal
• Cingulum: large convexity in cervical third
• Lingual fossa: smooth concavity in middle of ridges and cingulum, W-shape

3. Proximal Aspects

Mesial Aspect

• Crown shape: triangular/wedge
• Incisal ridge: midline axis
• Labial outline: convex, height of contour at cingulum level
• Lingual surface: convex (cervical third), concave (middle third), convex (incisal third)
• Cervical line: convex towards crown
• Root: smooth, convex, tapering

Distal Aspect

• Same as mesial aspect

4. Incisal Aspect

• No part of root visible
• Crown broader mesiodistally than labiolingually
• Labial outline: smooth, convex
• Lingual outline: narrower with convergence
• Incisal ridge: horizontal

Clinical Considerations

• Shovel-shaped incisors: common in mongoloid race, prominent marginal ridges, very concave lingual surface
• Developmental anomalies: talon cusp, fusion, gemination, dense invaginatus
• Trauma prone: due to their location
• Hutchinson's incisor (screwdriver-shaped incisors): feature of congenital syphilis, rhomboidal crown, shorter side towards incisal ridge, possible central notch