Contents■ Morphology of Permanent Mandibular Central Incisor■ Chronology and dimensions of Mandibular Central

Incisor■ Brief morphology of Mandibular Lateral Incisor

Objectives■ Identification of mandibular incisors from other teeth■ Understand the morphology of mandibular central and

lateral incisor■ Distinguish between the labial, lingual, mesial, distal and

incisal surfaces of the mandibular incisors

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

Mandibular Incisors

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1

1 : Mandibular Central Incisor

2 : Mandibular Lateral Incisor

Mandibular Central Incisor■ Mandibular Central Incisor is the smallest tooth in

the dentition

Labial aspect

Labial aspect■ Labial surface of mandibular central incisor is very

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

Narrowest tooth in the dentition

■ It is bilaterally symmetrical

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

Labial aspect

Both mesioincisal anddistoincisal angles are sharp

Lingual aspect

Lingual aspect■ The lingual aspect is concave from the incisal edge to

the cervical line

■ Cingulum is smooth and barely visible

Shallow lingual fossa andsmooth cingulum

■ 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.

Mesial aspect

Mesial aspect■ The labial outline is almost straight, except near

cervical third where it is convex

■ The labial surface is inclined lingually

Labial surface inclinedlingually

■ The lingual margin is ‘S’ shaped

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

S’ shaped lingual surface‘

Cervical line convex incisally

Distalaspect●Distal surface is very similar to the mesial surface.●The cervical line is less curved.

Distal aspect

Incisal aspect

Incisal aspect●This aspect illustrates the bilateral symmetry of this tooth.

●The labiolingual diameter is greater than mesiodistal diameter.

Bilaterally symmetrical

Labiolingually bigger than mesiodistally

■ Newly erupted teeth show mamelons which wear off upon mastication

Mamelons

Root

▪The root is single and straight.

▪ The deflection of the root if present is on the labial or distal side.

Single and straight root

3.0 2.0 5.3 6.0 3.5 5.0 12.5 9.0

Curvature of Cervical Line M D

LabiolingualDiameter atCervical Line

LabiolingualDiameter atCrest of Curvature

MesiodistalDiameter atCervical Line

MesiodistalDiameter atContact Area

RootLength

Crown Length

Average Dimensions in millimeters

CHRONOLOGYAppearance of enamel organ 5 m.i.uFirst evidence of calcification3-4 monthsCrown completion 4-5 yearsEruption 6-8 yearsRoot completion 10 years

Contact Area

Man L.I

Mesial Distal I3 I3

I3- Incisal third

Mandibular Lateral Incisor■ Mandibular lateral incisor is slightly wider

mesiodistally

■ 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

Cervical portion narrower

Fan shaped appearance

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

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

Lingual fossa more concave

Labial aspect Lingual aspect

Mesial aspectDistal aspect

Incisal aspect