Permanent Incisors Overview

Overview

This lecture provides an overview of permanent anterior teeth, focusing on the structure, function, and key characteristics of permanent incisors.

There are eight permanent incisors: four central and four lateral (two each per quadrant).
Incisors support lips, aid speech, and cut food.
All permanent anterior teeth (incisors and canines) are succedaneous, replacing primary teeth.

Only incisors have two incisal angles (mesial and distal) joined by the incisal ridge.
Maxillary central incisors are larger than maxillary laterals; both are wider mesiodistally than faciolingually.
Maxillary incisors have more pronounced lingual anatomy than mandibular incisors.
Incisors develop from four developmental lobes: three facial, one lingual (cingulum).
Mamelons are present at eruption but wear away over time due to attrition.

Anterior crowns are triangular from the proximal view, with the apex at the incisal ridge and base at the cervical line.
Contact areas are centered faciolingually in the incisal third on both mesial and distal surfaces.
Height of contour is in the cervical third for both facial and lingual surfaces.

Greater CEJ (cementoenamel junction) curvature in anterior vs. posterior teeth, especially on the mesial surface of maxillary central incisors.
All anteriors have a cingulum and marginal ridges on the lingual aspect.
Lingual fossa(e) are wide, shallow depressions; pits and grooves may harbor plaque, increasing caries risk, especially on maxillary laterals.

Incisors have a single root and one pulp canal.
Cross-sections: maxillary central (triangular), maxillary lateral (oval), mandibular incisors (elliptical).
Lingual aspect of the root is narrower, allowing easier access for instruments.

Lip overhang can lead to missed cleaning areas; use "flip the lip" when brushing.
Mouth breathing dries mucosa, increasing anterior inflammation.
Smile design: maxillary centrals should dominate the smile; midline should align with the philtrum.
Lip competence is the ability to close lips comfortably at rest.

Mandibular central incisors are the smallest permanent teeth; laterals are slightly larger.
Crown is wider faciolingually than mesiodistally.
Roots are longer than the crown; proximal surfaces have deep concavities.
Lingual anatomy is less pronounced, and there's greater plaque/calculus accumulation.
Mandibular anteriors often crowd over time due to mesial drift and attrition.

Succedaneous — teeth that replace primary teeth.
Incisal Ridge/Edge — the biting surface of newly erupted incisors (ridge) and worn ones (edge).
Mamelons — rounded enamel extensions from developmental lobes on incisal edge.
Cingulum — raised area on the cervical third of the lingual surface, from the fourth lobe.
CEJ (Cementoenamel Junction) — the line where the enamel and cementum meet.
Fossa — shallow depression on the lingual surface of anterior teeth.
Dens in dente — developmental anomaly of a tooth within a tooth.
Hutchinson incisor — notched incisor due to congenital syphilis.
Talon cusp — extra cusp projecting from cingulum area.

Review tooth models to identify key incisor features.
Memorize teeth numbers associated with specific traits (e.g., maxillary lateral incisors #7 and #10).
Prepare for hands-on identification and board exam distinctions (e.g., CEJ curvature, development anomalies).