Overview
This lecture reviews the distinguishing features of mandibular central and lateral incisors, including their anatomy, eruption patterns, and key identification points.
Mandibular Central Incisors (Teeth #24 and #25)
- Erupt between ages 6-7; roots complete by age 9.
- Smallest and simplest teeth in permanent dentition.
- Only have one antagonist: maxillary central incisors.
- Crown is symmetrical and fan-shaped from the facial view.
- Both incisal angles are sharp; mesioincisal angle is sharper than the distoincisal.
- Root is wider facial-lingual than mesiodistal; root is oval in cross-section with pronounced proximal concavities.
- Crown is narrower on the lingual side; lingual aspect is mostly featureless with centered, small cingulum and shallow fossa.
- Mesial CEJ curvature is more pronounced than distal.
- Incisal edge is slightly lingual to the long axis.
- Pulp cavity is simple: one canal and three pulp horns.
Mandibular Lateral Incisors (Teeth #23 and #26)
- Erupt between ages 7-8; roots complete by age 10.
- Slightly larger and less symmetrical than centrals with more detailed anatomy.
- Crown appears twisted or tilted distally at the cingulum junction.
- Single root is slightly longer and wider than central’s, with pronounced distal root concavities.
- Mesioincisal angle remains sharper than distoincisal.
- Lingual cingulum is small, shifted distally, and more prominent than in centrals.
- Incisal edge and ridge curve toward the lingual on the distal portion.
- Crown lacks bilateral symmetry; cingulum shift helps identify left/right and lateral versus central.
- Pulp cavity is simple: one canal and three pulp horns; root is elliptical in section.
- Mesial CEJ curvature is greater than distal.
- Incisal view shows a more rounded outline than central.
Review & Identification Tips
- Mandibular central: symmetrical crown, centered cingulum, incisal edge nearly straight.
- Mandibular lateral: crown and cingulum twisted/shifted distally, incisal ridge curves to lingual.
- Both central and lateral mandibular incisors have deep mesial and distal root depressions.
Key Terms & Definitions
- Antagonist — The opposing tooth that contacts a given tooth in occlusion.
- Cingulum — Bulge at the cervical third of the lingual surface of anterior teeth.
- CEJ (Cervical Enamel Junction) — The junction where the enamel of the crown meets the cementum of the root.
- Incisal Ridge/Edge — The cutting surface of anterior teeth.
- Fossa — A shallow depression on the tooth surface.
- Proximal Root Concavity — Longitudinal root depression found on the mesial/distal root surfaces.
Action Items / Next Steps
- Examine your mandibular central and lateral incisors, noting crown shape, cingulum position, and incisal edge curvature.
- Practice identifying left/right teeth by observing the cingulum shift and CEJ curvature.
- Prepare responses to review questions about incisal ridge twists and root depressions for future quizzes.