Lower Central & Lateral Incisor
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Transcript of Lower Central & Lateral Incisor
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
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■ 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■ 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●This aspect illustrates the bilateral symmetry of this tooth.
●The labiolingual diameter is greater than mesiodistal diameter.
Bilaterally symmetrical
Labiolingually bigger than mesiodistally
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
■ 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