MAXILLARY LATERAL INCISORS

MAXILLARY LATERAL INCISORINTRODUCTION

Resembles the C-I in its form.

The dimensions of the crown are much smaller.

The root length which is relatively longer.

Supplements the C-I in function.

Development of this tooth may vary considerably .

It is the most variable tooth next to third molar.

Frequently (Congenitally) missing tooth

Peg-laterals Conical teeth

In some individuals they are entirely missing, here the

central incisor may be in contact distally with the canine.

Supernumerary lateral incisors are not uncommon.

Anomalies :

i) large pointed tubercle as a part of the cingulum varying from being round to conical,

ii) or pits, grooves in the cingulum.

iii) presence of deep developmental grooves extending down to the root lingually with a deep fold in the cingulum,

iv) twisted roots,

v) distorted crowns.

TOOTH NUMBERING SYSTEMS

ADA / Universal system - 7 10

FDI system - 12 , 22

ZSIGMONDY PALMER system - 2 2

CHRONOLOGY:First evidence of calcification 1 yr

Enamel completed 4 to 5 yr

Eruption 8 to 9 yr

Root completed 11 yr

DIMENSIONS:

Cervico-incisal length of crown 9 mm Length of Root 13 mm

M - d dm of crown 6.5 mm

M - d dm of crown at cervix 5.0 mm

L - p dm of crown 6.0 mm

L - p dm of crown at cervix 5.0 mm

Mesial Curvature of cervical line 3.0 mm

Distal Curvature of cervical line 2.0 mm

LABIAL

ASPECT

LABIAL ASPECT Crown is narrower mesio-distally by about 2 mm and shorter inciso-cervically by about 2 3 mm than C-I The incisal ridge is rounded.

Mesial outline of the crown resembles that of the C-I.

M-i & d-i angles are more rounded than that of the C-I .

Distal margin is shorter than the mesial margin.

Both the mesial and the distal crown margins are rounder and converge root wards.

It is more convex than the C-I

MCA - is at the junction of incisal and middle third.

DCA - is at the middle third.

Root length is greater in proportion to its crown length than that of the central incisor.

Root is about 11/2 times the length of the crown.

Root tapers evenly from the cervical line to a point about 2/3rds of its length apically.

Some roots are straight.

Root curvature , if present , is seen in the apical 3rd .

The root curves sharply in a distal direction and ends in a pointed apex

LIGUAL

ASPECT

LINGUAL ASPECT MMR , DMR & Cingulum are more prominent those of C-I

Lingual fossa is deep with developmental grooves.

Linguo-incisal ridge is well-developed.

The tooth shows a lingual taper like the C-I.

This surface is triangular in shape.

Lingual fossa is more concave & circumscribed than that

found on the central incisor.

MESIAL

ASPECT

MESIAL ASPECT Triangular in shape from this aspect.

Similar to that of a small C-I, except that the root appears longer.

Cingulum is more convex than that of the C-I.

The CEJ is less convex than that of the C-I.

Heavy development of the incisal ridge makes the incisal portion appear thicker than that of central incisor.

The root appears as a tapered cone with a bluntly rounded

apex.

Sometimes, the labial outline of the root from this aspect is straight.

A line drawn through the center of the root tends

to bisect the incisal ridge of the crown, as in the C-I

DISTAL

ASPECT

DISTAL ASPECT The width of the crown appears thicker from this aspect, than it does on the mesial aspect.

Curvature of the cervical line is ~ an mm less on this side.

A developmental groove can also be seen distally on this crown extending on the root for part or all of its length.

INCISAL ASPECT

INCISAL ASPECTIt may resemble the maxillary central incisor or a small canine from this aspect.

It is shorter than that of central incisor.

Mammelons are indistinct even in the newly erupted teeth.

The L-l dm > M-d dm with large cingulum & incisal ridge if this variation is present, it resembles a small canine.

If the tooth confirms in development to the C-I, then it

resembles the C-I , except in size

Maxillary laterals exhibit more convexity labially & lingually

from the incisal aspect than the maxillary central incisor.

Pulp canal & pulp chamber have the similar features as that of the central incisor.

MANDIBULAR LATERAL INCISORS

MANDIBULAR LATERAL INCISORINTRODUCTION:

Resembles the mandibular C-I very closely.

The two incisors- mandibular C & L -Incisors, operate in

the dental arch as a team, thus, their functional form is

related.

It is slightly larger than the mandibular central incisor.

TOOTH NUMBERING SYSTEMS

ADA / Universal system - 26 23

FDI system - 42 , 32

ZSIGMONDY PALMER system - 2 2

CHRONOLOGY:First evidence of calcification 3 to 4 mo

Enamel completed 4 to 5 yr

Eruption 7 to 8 yr

Root completed 10 yr

DIMENSIONS:

Cervico-incisal length of crown 9 . 5 mm

Length of Root 14. 0 mm

M d dm of crown 5 . 5 mm

M d dm of crown at cervix 4 . 0 mm

L - l dm of crown 6 . 5 mm

L - l dm of crown at cervix 5 . 8 mm

Mesial Curvature of cervical line 3 . 0 mm

Distal Curvature of cervical line 2 . 0 mm

L

A

B

I

A

L

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S

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LINGUAL

ASPECT

LABIAL & LINGUAL ASPECTS It is similar to central incisor in all respects

except, its diameter mesiodistally is more by

added fraction of 1mm.

MESIAL

ASPECT

DISTAL

ASPECT

MESIAL & DISTAL ASPECTS The mesial side is longer than the distal side of the

crown, & so, the incisal edge slopes distally.

The DCA is placed more cervically than the MCA, to

contact properly the MCA of the mandibular canine.

The curvatures of the cervical line mesially & distally are

also similar to that of the C-I.

There may be a deeper concavity immediately above the

cervical line on the distal surface of mandibular L-I.

Crown of lateral incisor is only a fraction of an mm longer than that of central incisor, but the root may be considerably longer.

Root form is similar to that of central incisor, with

developmental depressions mesially & distally.

I N C I S A L A S P E C T

INCISAL ASPECT Incisal edge is not at right angles to a line bisecting the

root & crown labiolingually.

The incisal edge follows the curvature of mandibular dental

arch, giving the crown of mandibular lateral incisor the

appearance of being slightly twisted on its root base.

The labiolingual root axes of Mandibular central & lateral

incisors remain parallel in the alveolar process, even

though the incisal ridges are not directly in line.

Variations of mandibular lateral incisor include the

bifurcation of root apex, deep proximal grooves.

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