Maxillary Lateral and Mandibular Incisors

Anatomy Of The
Maxillary Lateral
Incisors And
Mandibular
Central And
Lateral Incisors
Howard Chi D.M.D.

Learning Objectives
• Anatomy of the maxillary lateral incisors
• Anatomy of the mandibular central incisors
• Anatomy of the mandibular lateral incisors

Anatomy of the
Maxillary Lateral
Incisors

Morphology Of The Crown
From The Labial
• Similar to that of a
central incisor
• More convex, or less
flat mesiodistally

Morphology Of The Crown
From The Labial
• Appears more oblong
cervicoincisally
• Mamelons and labial
depression less
prominent than central

Crown Size And Shape
From The Labial
• Narrower by about 2mm
from that of a central incisor
• This yields a long,
slender look
• Outline is less symmetrical
than a central incisor + 2 mm

Crown Incisal Proximal Angles
From The Labial
• Both the mesio and
distoincisal angle are
more rounded than
central incisor
• Mesioincisal angle is
more acute than
central incisor

Crown Incisal Proximal Angles
From The Labial
• Distoincisal is wider and
more obtuse than
maxillary central incisor
• Incisal angle slope more
cervically towards the
distal on a maxillary lateral

Crown Contact Areas
From The Labial
• Mesial contact is in the
incisal near the junction of
the incisal and middle thirds
• Distal contact is at the
junction of the incisal
and middle thirds

Tooth Proportions
From The Labial
• The root is narrower, but
can be longer than that of a
maxillary central incisor
• This makes the root longer
in proportion to the crown
than a central incisor

Root From The Labial
• The root tapers evenly toward
the rounded apex
• The root commonly curves
distally

Lingual Fossa
Of The Crown
• Is smaller in area than
a central incisor
• More pronounced than
a central incisor
• May appear either
shallow or deep

Cingulum Of A Maxillary
Lateral Incisor
• Narrower than a
central incisor
• Almost centered on
the long axis of
the root

Marginal Ridges Of A Maxillary
Lateral Incisor
• Developed to different
degrees on different teeth
• May be prominent
or inconspicuous
• Can be worn from
attrition

Marginal Ridges Of A Maxillary
Lateral Incisor
• Mesial marginal ridge outline is
nearly straight
• Distal marginal ridge is shorter
and curved incisocervically
• Shortness of the distal marginal
ridge is due to slope of the incisal ridge

Lingual Anatomy Of The Crown
• May possess lingual accessory
ridges near cingulum
• Fewer and less common than the
central incisor's
• A lingual pit is frequently present
and often restored to arrest decay

Root From The Lingual
• Narrower on the lingual
side than the labial
• Surface root depression
present on the mesial

Incisal Ridge From The Proximal
Aspect
• Usually 1.0 to 1.5 mm thick
and labial to the root axis
• Sloped cervically toward the
lingual from its most labial
portion

Cervical Line From the Proximal
Aspect
• Curvature is deep
on the mesial
(2.5mm)
• More curved on
mesial than on
the distalMesial #7 Distal #7
2.5mm

Root Outline From The Mesial
• Appears blunt from
the proximal
• Root ratio is slightly greater
than the central incisor
Mesial #7

Root Depressions From The
Proximal
• Similar to the
central, found
on the mesial
mid-root
Mesial #7 Distal #7

Root Depressions From The
Proximal
• Mesial surface
is the least
convex of the
four sides
(another way
of saying its
the flattest)
Mesial #7 Distal #7

Crown Proportion From The
Incisal Aspect
The mesiodistal
measurement
is greater than
the faciolingual
• On some this dimension may be the same

Crown Outline From The Incisal
• Is less symmetrical, but in general,
resembles the central
• It is narrower mesiodistally than the central
• Cingulum is nearly centered mesiodistally

Incisal Ridge Contour
• Incisal ridge straighter mesiodistally than a
central incisor

Cingulum From An
Incisal Aspect
• Centered
mesiodistally
and noticeably
more convex than the central incisor

Labial Contour From
The Incisal Aspect
• Noticeably more convex than the maxillary
central incisor (type trait)

Anatomy Of The
Mandibular Central Incisors

Mandibular Central Incisor From
The Labial Aspect
• The surface of the crown
is nearly smooth
• Can have two shallow
depressions in the incisal third
(similar to maxillary, but far less
pronounced)

• Mamelons are usually present
on newly emerged teeth
• Quickly worn off with contact
with maxillary teeth (if not,
suspect malocclusion)
The Labial Aspect

• Crown is five-eighths the width
of a maxillary central
• Crown is proportionally narrow in
comparison to its length
The Labial Aspect

• The tooth is so symmetrical it is
difficult to tell left from right
• Only difference is the mesial
cervical line curve more incisally
than the distal
The Labial Aspect

• The mesial and distal outlines is
straight in the incisal third
• The crown tapers to the cervical
third
• Contacts are well within the
incisal one third
The Labial Aspect

• Labial surface is convex
mesiodistally in the cervical third
• Mesio and distoincisal angle is
nearly 90 degrees
The Labial Aspect

• Distoincisal angle may be more
rounded (slightly) than the
mesioincisal angle
The Labial Aspect

• Mesial and distal contact areas are
within the incisal third at roughly
the same height (type trait)
• Root longer than crown
proportionally compared to the
maxillary incisors
The Labial Aspect

• The root is narrow mesiodistally,
but wide faciolingually
• The root is tapered evenly on both
sides from the cervical line to the
apex, root tip may curve to the
distal
The Labial Aspect

The Lingual Aspect
• The outline is much more
symmetrical than all other incisors
• The lingual crown surface is
smooth and shallow with a slight
concavity in the middle and
incisal thirds

• The cingulum is convex, small
and centered
• The marginal ridges and lingual
fossa are scarcely discernible, if at
all
• No grooves, pits or accessory
ridges are present
The Lingual Aspect

The Proximal Aspect
• The incisal edge is on or lingual
to the long axis of the root
• Mesial cervical line (CEJ) extends
2mm incisally
• Distal cervical line extends .4 mm
less than the mesial

• The facial height of contour is
located in the cervical third
• The lingual height of contour is
located on the cingulum, within
the cervical third
The Proximal Aspect

• The labial contour is so slightly
curved that it often appears flat
• The lingual contour is convex on
the cingulum, concave in the
fossa and flat towards the incisal
The Proximal Aspect

• The facial and lingual sides of the
root are nearly straight from the
cervical line to the middle third
• The root then tapers to its apex
The Proximal Aspect

• Roots are flat mesiodistally
compared to their maxillary
counterparts
• Roots are wider faciolingually
than mesiodistally by
approximately 2mm
The Proximal Aspect

Root depressions can be
found on both the
mesial and distal
aspects in the
middle third
of the roots
The Proximal Aspect
#25 Mesial #25 Distal

The Incisal Aspect
• The labiolingual measurement of the crown is
greater than the mesiodistal measurement (this is
quite different from the maxillary counterparts)

• The labial and lingual height of contour is
centrally located
• The incisal edge runs in a straight line
mesiodistally and is roughly 2mm thick
The Incisal Aspect

• The cingulum is centered, smooth and has a convex
outline
• The labial surface is slighly convex in the incisal
one third and noticeably convex in the cervical third
The Incisal Aspect

Anatomy Of The
Mandibular Lateral Incisors

Mandibular Lateral Incisor From
The Facial View
• Similar to the central, smooth
and minimal depressions
• Labial surface is convex
mesiodistally, more in the
cervical third and less in the
incisal third

• Crown is tilted distally on the
root, giving a bent appearance
• This makes the distal outline
of the crown shorter than the
mesial aspect
The Facial View

• The distoincisal angle is
noticeably more rounded than
the mesioincisal angle
• This aids in telling left
from right
The Facial View

• The mesial contact is in the
incisal third, near the incisal edge
• The distal contact is in the
incisal third, but cervical to the
level of the mesial contact
The Facial View

• Crown is narrower with respect
to its length
• Root is narrow mesiodistally,
tapering gradually from the
cervical line to the apex. It may
have a distal curvature
The Facial View

The Lingual View
• Similar to the central, but not
bilaterally symmetrical
• Crown is tilted distally, and tapers
lingually in the middle and cervical
thirds

• The cingulum is slightly distal
to the long axis of the root, similar
to the maxillary central
• This makes the mesial marginal
ridge longer than the distal
The Lingual View

• Marginal ridges and lingual fossa
are not conspicuous and
generally smooth
• The root is narrower lingually
than facially
The Lingual View

The Proximal View
• The incisal edge is on or
lingual to the long axis
of the root
• From the mesial a distolingual
twist of the incisal edge places
the distal portion more lingual
Central Lateral

• The C.E.J. curves 2 mm
incisally on the mesial aspect
• The C.E.J. curve 1.4 mm
incisally on the distal aspect
The Proximal View

• The facial and lingual heights
of contour are in the cervical
third
• The labial outline is nearly
flat in the middle and incisal
thirds
The Proximal View

• The root is straight from
cervical to middle third
• The distal portion of the
root contains a depression
that is more distinct than
the mesial
The Proximal View

The Incisal View
• The crown is broader faciolingually than
mesiodistally
• Not bilaterally symmetrical, distal is twisted

• The cingulum is off center to the distal with
a barely dicernible lingual fossa
• The labial outline is slightly convex in the
incisal one third
The Incisal View

Maxillary Lateral and Mandibular Incisors

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