Human dentition Dr. Hazem Al Ajrami First Year in Dentistry First Semester Al-Azhar University - Gaza lecture 6

2. College of DentistryCollege of Dentistry
Human Dentition IHuman Dentition I
Maxillary Lateral IncisorMaxillary Lateral Incisor
Dr. Hazem Al AjramiDr. Hazem Al Ajrami

3.  Universal Numbering System:Universal Numbering System:
7 and 107 and 10
 Palmer Notation System:Palmer Notation System:
 FDI Numbering System:FDI Numbering System:
12 and 2212 and 22
22 andand 22

4.  Chronology:Chronology:
A.A. First evidence of calcification:First evidence of calcification: 11 year.year.
B.B. Enamel completed:Enamel completed: 44 toto 55 years.years.
C.C. Eruption:Eruption: 88 -- 99 years.years.
D.D. Root completed:Root completed: 1111 years.years.

5.  The maxillary lateral incisors complement theThe maxillary lateral incisors complement the
central incisors in function. It is smaller in allcentral incisors in function. It is smaller in all
dimensions than the central except root length.dimensions than the central except root length.
It is about 2 mm. narrower mesiodistally andIt is about 2 mm. narrower mesiodistally and
2-3 mm. shorter than the central incisor.2-3 mm. shorter than the central incisor.
 Since it resembles the maxillary central incisorSince it resembles the maxillary central incisor
in form, direct comparisons will be made within form, direct comparisons will be made with
the central incisor in its description.the central incisor in its description.

6. This tooth differs from the central incisor inThis tooth differs from the central incisor in
this-its development may vary considerably.this-its development may vary considerably.
Maxillary lateral incisors vary in form more thanMaxillary lateral incisors vary in form more than
any other tooth in the mouthany other tooth in the mouth exceptexcept the thirdthe third
molar. If the variation is too great, it is consider amolar. If the variation is too great, it is consider a
developmental anomaly. A not uncommondevelopmental anomaly. A not uncommon
situation is to find maxillary lateral incisors with asituation is to find maxillary lateral incisors with a
nondescript, pointed form; such teeth are callednondescript, pointed form; such teeth are called
"peg-shaped" laterals (with poorly developed"peg-shaped" laterals (with poorly developed
central lobe). In some individuals, the lateralcentral lobe). In some individuals, the lateral
incisors are missing entirely: in these cases, theincisors are missing entirely: in these cases, the
maxillary central incisor may be in contact distallymaxillary central incisor may be in contact distally
with the canine.with the canine.

9. One type of malformed maxillary lateralOne type of malformed maxillary lateral
incisor will have a large pointed tubercle asincisor will have a large pointed tubercle as
part of the cingulum, some will have deeppart of the cingulum, some will have deep
developmental grooves which extend down ondevelopmental grooves which extend down on
the root palatally with a deep fold in thethe root palatally with a deep fold in the
cingulum; and some will show twisted roots,cingulum; and some will show twisted roots,
distorted crowns, and so forth.distorted crowns, and so forth.

10. Cervico-Cervico-
IncisalIncisal
Length ofLength of
CrownCrown
Length ofLength of
RootRoot
MesiodistalMesiodistal
Diameter ofDiameter of
CrownCrown
MesiodistalMesiodistal
Diameter ofDiameter of
Crown atCrown at
CervixCervix
MaxillaryMaxillary
CentralCentral
IncisorIncisor
10.510.5 1313 8.58.5 77
MaxillaryMaxillary
LateralLateral
IncisorIncisor 99 1313 6.56.5 55

11. Labio-Labio-
palatalpalatal
DiameterDiameter
of Crownof Crown
Labio-Labio-
palatalpalatal
DiameterDiameter
of Crownof Crown
at Cervixat Cervix
CurvatureCurvature
ofof
CervicalCervical
LineLine
(Mesial)(Mesial)
CurvatureCurvature
ofof
CervicalCervical
LineLine
(Distal)(Distal)
MaxillaryMaxillary
CentralCentral
IncisorIncisor
77 66 3.53.5 2.52.5
MaxillaryMaxillary
LateralLateral
IncisorIncisor 66 55 33 22

12. Labial AspectLabial Aspect
Although the labial aspect of the maxillaryAlthough the labial aspect of the maxillary
lateral incisor may appear to favor that of thelateral incisor may appear to favor that of the
central incisor, usually it has more curvature,central incisor, usually it has more curvature,
with a rounded incisal edge and roundedwith a rounded incisal edge and rounded
incisal angles mesially and distally. Althoughincisal angles mesially and distally. Although
the crown is smaller in all dimensions, itsthe crown is smaller in all dimensions, its
proportions usually correspond to those of theproportions usually correspond to those of the
central incisor.central incisor. Like the central incisor, labialLike the central incisor, labial
developmental grooves are present.developmental grooves are present.

13. MesialDistal

14. The mesial outlineThe mesial outline of the crown from theof the crown from the
labial aspect resembles that of the centrallabial aspect resembles that of the central
incisor, with a more rounded mesioincisalincisor, with a more rounded mesioincisal
angle.angle. The crestThe crest of contour mesially is usuallyof contour mesially is usually
at the point of junction of the middle andat the point of junction of the middle and
incisal thirds; occasionally, in the so-calledincisal thirds; occasionally, in the so-called
square forms, the mesioincisal angle is almostsquare forms, the mesioincisal angle is almost
as sharp as that found on most maxillaryas sharp as that found on most maxillary
central incisors. However, a more roundedcentral incisors. However, a more rounded
mesioincisal angle is seen more frequently.mesioincisal angle is seen more frequently.

15. The distal outlineThe distal outline of the crown from theof the crown from the
labial aspect differs somewhat from that of thelabial aspect differs somewhat from that of the
central incisor. The distal outline is alwayscentral incisor. The distal outline is always
more rounded, andmore rounded, and the crestthe crest of contour isof contour is
more cervical, usually in the center of themore cervical, usually in the center of the
middle third. The incisal outline is moremiddle third. The incisal outline is more
curved than the central incisor because of thecurved than the central incisor because of the
more rounded incisal angle. Some formsmore rounded incisal angle. Some forms
describe a semicircular outline distally fromdescribe a semicircular outline distally from
the cervix to the center of the incisal edge.the cervix to the center of the incisal edge.

16.  The labial surface of the crown is more convexThe labial surface of the crown is more convex
than that of the central incisor except in somethan that of the central incisor except in some
square and flat-faced forms.square and flat-faced forms.
 This tooth is relatively narrow mesiodistally,This tooth is relatively narrow mesiodistally,
usually about 2 mm. narrower than the centralusually about 2 mm. narrower than the central
incisor. The crown on the average will measureincisor. The crown on the average will measure
from 2 to 3 mm. shorter cervicoincisally than thatfrom 2 to 3 mm. shorter cervicoincisally than that
of the central incisor, although the root is usuallyof the central incisor, although the root is usually
as long if not somewhat longer than that of theas long if not somewhat longer than that of the
central incisor.central incisor.
 The cervical line curves apically with about theThe cervical line curves apically with about the
same depth of curvature as on central incisor.same depth of curvature as on central incisor.

17.  As a rule, its root length is greater inAs a rule, its root length is greater in
proportion to its crown length than that of theproportion to its crown length than that of the
central incisor. The root is often about 1 ½central incisor. The root is often about 1 ½
times the length of the crown.times the length of the crown.
 The root tapers evenly from the cervical line toThe root tapers evenly from the cervical line to
a point approximately two-thirds of its lengtha point approximately two-thirds of its length
apically. In most cases, it curves sharply fromapically. In most cases, it curves sharply from
this location in a distal direction and ends in athis location in a distal direction and ends in a
pointed apex. Although the curvature distallypointed apex. Although the curvature distally
is typical, some roots are straight, and someis typical, some roots are straight, and some
may be found curving mesially. As mentionedmay be found curving mesially. As mentioned
previously, this tooth may show considerablepreviously, this tooth may show considerable
variance in its crown form: the root form mayvariance in its crown form: the root form may
be more characteristic.be more characteristic.

18. Palatal AspectPalatal Aspect
Mesial and distal marginal ridges areMesial and distal marginal ridges are
marked, and the cingulum is usuallymarked, and the cingulum is usually
prominent, with a tendency toward deepprominent, with a tendency toward deep
developmental grooves within the palataldevelopmental grooves within the palatal
fossa, where it joins the cingulum. Thefossa, where it joins the cingulum. The
palatoincisal ridge is well developed, and thepalatoincisal ridge is well developed, and the
palatal fossa is more concave andpalatal fossa is more concave and
circumscribed than that found on the centralcircumscribed than that found on the central
incisor.incisor.

19. DistalMesial

20. The tooth tapers toward the palatal,The tooth tapers toward the palatal,
resembling a central incisor in this respect. It isresembling a central incisor in this respect. It is
not uncommon to find a deep developmentalnot uncommon to find a deep developmental
groove at the side of the cingulum, usually on thegroove at the side of the cingulum, usually on the
distal side, which may extend up on the root fordistal side, which may extend up on the root for
part or all of its length. Faults in the enamel ofpart or all of its length. Faults in the enamel of
the crown are often found in the deep portions ofthe crown are often found in the deep portions of
these developmental grooves. The palatal pit isthese developmental grooves. The palatal pit is
frequently seen at the upper border of thefrequently seen at the upper border of the
cingulum and it is the common site of thecingulum and it is the common site of the
beginning of caries.beginning of caries.

21. Mesial AspectMesial Aspect
 The mesial aspect of the maxillary lateral incisor isThe mesial aspect of the maxillary lateral incisor is
similar to that of a small central incisor except thatsimilar to that of a small central incisor except that
the root appears longer. The crown is shorter, thethe root appears longer. The crown is shorter, the
root is relatively longer, and the labiopalatalroot is relatively longer, and the labiopalatal
measurement of the crown and root is a millimetermeasurement of the crown and root is a millimeter
or so less than the maxillary central incisor of theor so less than the maxillary central incisor of the
same mouth.same mouth.
 The curvature of the cervical line is marked in theThe curvature of the cervical line is marked in the
direction of the incisal edge, although because ofdirection of the incisal edge, although because of
the small size of the crown the actual extent ofthe small size of the crown the actual extent of
curvature is less than that found on the centralcurvature is less than that found on the central
incisor.incisor.

23.  The heavy development of the incisal edgeThe heavy development of the incisal edge
accordingly makes the incisal portion appearaccordingly makes the incisal portion appear
somewhat thicker than that of the centralsomewhat thicker than that of the central
incisor.incisor.
 The root appears as a tapered cone from thisThe root appears as a tapered cone from this
aspect, with a bluntly rounded, apical end.aspect, with a bluntly rounded, apical end.
This varies in individuals, sometimes beingThis varies in individuals, sometimes being
quite blunt, while at other times it is pointed.quite blunt, while at other times it is pointed.
In a good many cases, the labial outline of theIn a good many cases, the labial outline of the
root from this aspect is straight. As in theroot from this aspect is straight. As in the
central incisor, a line drawn through the centercentral incisor, a line drawn through the center
of the root tends to bisect the incisal edge ofof the root tends to bisect the incisal edge of
the crown.the crown.

24. Distal AspectDistal Aspect
The curvature of the cervical line is usually aThe curvature of the cervical line is usually a
millimeter or so less in depth than on the mesialmillimeter or so less in depth than on the mesial
side. It is not uncommon to find a developmentalside. It is not uncommon to find a developmental
groove distally on this crown extending on thegroove distally on this crown extending on the
root for part or all of its length.root for part or all of its length.
The distal surface is smaller, but more convexThe distal surface is smaller, but more convex
in all dimensions than the mesial surface.in all dimensions than the mesial surface.
The contact area is shorter, narrower andThe contact area is shorter, narrower and
more cervically placed than the mesial contactmore cervically placed than the mesial contact
area.area.

26. Incisal AspectIncisal Aspect
The incisal aspect of this tooth sometimesThe incisal aspect of this tooth sometimes
resembles that of the central incisor, or it mayresembles that of the central incisor, or it may
resemble that of a small canine. If the toothresemble that of a small canine. If the tooth
conforms in development to its central incisorconforms in development to its central incisor
neighbor in other respects, it will, from theneighbor in other respects, it will, from the
incisal aspect, resemble a central incisorincisal aspect, resemble a central incisor
except in size.except in size.

28.  The cingulum, however, may be large; the incisalThe cingulum, however, may be large; the incisal
edge also; the labiopalatal dimension may beedge also; the labiopalatal dimension may be
greater than usual in comparison with thegreater than usual in comparison with the
mesiodistal dimension. If these variations aremesiodistal dimension. If these variations are
present, the tooth has a marked resemblance to apresent, the tooth has a marked resemblance to a
small caninesmall canine.. All maxillary lateral incisorsAll maxillary lateral incisors
exhibit more convexity labially and palatallyexhibit more convexity labially and palatally
from the incisal aspect than maxillary centralfrom the incisal aspect than maxillary central
incisors. And this give the incisal aspect a moreincisors. And this give the incisal aspect a more
rounded or oval shape rather than triangularrounded or oval shape rather than triangular
shape found in central incisor.shape found in central incisor.
 The lateral incisor is more narrow mesiodistally.The lateral incisor is more narrow mesiodistally.

29. Carving Maxillary Central IncisorCarving Maxillary Central Incisor

41. Thank YouThank You