Mandibular IncisorsMandibular Incisors

Dr. Syed Sadatullah Dr. Syed SadatullahIbnsina National CollegeIbnsina National College

JeddahJeddah

Introduction

Mandibular incisors are four in number

Mandibular central incisor and lateral are similar in anatomy and complement each other in function

They are smaller than the maxillary incisors

Mandibular central incisor erupts between the age of 6 and 7

Mandibular lateral incisor erupts between the age of 6 and 8

Labial aspect Labial surface of mandibular central incisor is

very small. It is the narrowest tooth mesiodistally of all the permanent teeth

It is bilaterally symmetrical

It is the only incisor where both mesioincisal and distoincisal angles are sharp and at right angles

The labial surface is inclined lingually

Labial aspect

Lingual aspect The lingual aspect is concave from the incisal

edge to the cervical line

Cingulum is smooth and barely visible

The surface is smooth and devoid of any grooves. No other tooth in the mouth, except the mandibular lateral incisor, shows so few developmental lines and grooves.

Lingual aspect

Mesial aspect The labial outline is almost straight, except near

cervical third where it is convex

The lingual margin is ‘S’ shaped

The cervical line on the mesial and distal surface is convex incisally

Mesial aspect

Distalaspect Distal surface is very similar to the mesial

surface. The cervical line is less curved.

Distal aspect

Incisal aspect This aspect illustrates the bilateral symmetry of

this tooth.

The labiolingual diameter is greater than mesiodistal diameter.

Newly erupted teeth show mamelons which wear off upon mastication

Incisal aspect

RootThe root is single and straight.

The deflection of the root if present is on the labial or

distal side.

3.0 2.0 5.3 6.0 3.5

5.0 12.5 9.0

Curvature of Cervical Line

M D

Labiolingual

Diameter at

Cervical Line

Labiolingual

Diameter at

Crest of Curvature

Mesiodistal

Diameter at

Cervical Line

Mesiodistal

Diameter at

Contact Area

Root

Length

Crown Length

Average Dimensions in millimeters

Mandibular Lateral Incisor Mandibular lateral incisor is slightly wider

mesiodistally

The concavity in the lingual aspect is slightly more when compared to mandibular central incisor

The cervical portion of the lingual aspect is narrower while the incisal portion is wider. This gives the crown a more or less a fan shaped appearance

The incisal edge follows the mandibular arch, giving the crown a slightly twisted appearance on its root

Labial aspect

Lingual aspect

Mesial aspectDistal aspect

Incisal aspect