Mandibular Incisors
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Transcript of Mandibular Incisors
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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
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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
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Mandibular Incisors
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1 : Mandibular Central Incisor2 : Mandibular Lateral Incisor
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Mandibular Central Incisor Mandibular Central Incisor is the smallest tooth in
the dentition
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Labial aspect
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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
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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 and distoincisal angles are sharp
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Lingual aspect
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Lingual aspect The lingual aspect is concave from the incisal
edge to the cervical line
Cingulum is smooth and barely visible
Shallow lingual fossa and smooth cingulum
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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.
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Mesial aspect
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Mesial aspect The labial outline is almost straight, except near
cervical third where it is convex
The labial surface is inclined lingually
Labial surface inclined lingually
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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
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Distalaspect
Distal surface is very similar to the mesial surface.
The cervical line is less curved.
Distal aspect
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Incisal aspect
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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
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Newly erupted teeth show mamelons which wear off upon mastication
Mamelons
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RootThe root is single and straight.
The deflection of the root if present is on the labial or distal side.
Single and straight root
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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.u
First evidence of calcification 3-4 months
Crown completion 4-5 years
Eruption 6-8 years
Root completion 10 years
Contact Area Man L.I
Mesial Distal
I3 I3
I3- Incisal third
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Mandibular Lateral Incisor Mandibular lateral incisor is slightly wider
mesiodistally
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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
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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
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Labial aspect
Lingual aspect
Mesial aspect Distal aspect
Incisal aspect