Preclinics of Dental Prosthetics · MU Sofia

9. Morphology of permanent incisors.

Covers the eight permanent incisors, their coding and functions, and the features all incisors share, such as crown outline, corner shape, wear pattern and the mamelons of new teeth. It then compares the upper central, upper lateral, lower central and lower lateral in a table covering size, corners, lingual side, contacts and roots. Closing notes address the upper central as a weak bridge abutment, the lingual pit of the upper lateral, and a quick way to tell upper from lower incisors.

Inside: 5 sections · 1 labelled picture · 1 table · 13 flashcards · 3 min

Topic 9 of 75 in the MU Sofia syllabus for Preclinics of Dental Prosthetics (Dental Medicine, Year 2). The free AceMed note covers it in 5 sections, about 267 words (3 min of reading), with 13 flashcards.

In this note

  1. Introduction
  2. What incisors do
  3. Features all incisors share
  4. Each incisor
  5. Prosthetic notes

Introduction

There are eight permanent incisors: a central and a lateral in each quadrant, coded 11, 12, 21, 22 above and 31, 32, 41, 42 below.

What incisors do

  1. Cut food, working against the opposite incisors.
  2. Shape speech sounds with the lips and tongue.
  3. Support the lips and give the face its appearance.
  4. Guide the mandible backward in the last moment of closing, just before the back teeth meet, so the back teeth aren't overloaded.

Features all incisors share

  • From the labial side the crown is a rectangle, longer than wide, narrowest at the cervix and widest at the incisal third.
  • The mesioincisal corner is almost a right angle; the distoincisal corner is more rounded. This is the key mark for telling right from left.
  • From the proximal side the crown is a wedge; the lingual outline is S-shaped, convex over the cingulum and concave in the lingual fossa.
  • Two shallow vertical developmental depressions divide the labial surface into mesial, middle and distal lobes.
  • New incisors carry three small bumps on the edge, the mamelons, which soon wear away (attrition).
  • The crest of curvature of labial and lingual surfaces lies in the cervical third, near the CEJ.
  • Wear pattern: upper incisors wear on the lingual side of the edge, lower incisors on the labial side.

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