Morphology and histology

Morphology And Histology of
Primary And Permanent teeth

R.Hemalatha
st
1 Yr

Introduction and Nomenclature
The teeth are arranged in upper and lower arches. Those teeth in the upper
arch are termed maxillary, because they are set in the upper jaw, which is
the maxilla (Plural - maxillae). The teeth in the lower arch are termed
mandibular, because they are located in the lower jaw, which is the
mandible. The mandible is the movable member of the two jaws, while
the maxilla is stationary.
• B. The imaginary vertical line which divides each arch, as well as the
body, into two approximately equal halves, is the midline. Strictly
speaking, this vertical division is not a one-dimensional line at all, but
rather a two-dimensional plane, termed the mid-sagittal lane.

• The two approximately equal portions of each arch divided by the
midline are termed g&rants, since there are four in the entire mouth.
They are termed:
• maxillary (upper) right.
• maxillary (upper) left.
• mandibular (lower) right.
• mandibular (lower) left
• The manner in which the mandibular teeth contact the maxillary teeth
is called occlusion. The term for the process of biting or chewing of
food is mastication midline

Classification of Dentitions:
•

•

A. The human dentition is termed heterodont, which means it is
comprised of different types, or classes, of teeth to perform different
functions in the mastication process. In comparison, a homodont
dentition is one in which all of the teeth are the same in form and type.
This sort of dentition is found in some of the lower vertebrates.
B. Furthermore, man has two separate sets of teeth, or dentitions. This
is termed diphyodonta as opposed to monophyodont when there is
only one set of teeth, and polyphyodont, when more than two. or
continuous, sets of teeth are developed throughout life.

•

In man, the two dentitions are termed deciduous and permanent,
while the transitional phase when both deciduous and permanent
teeth are present is called the mixed dentition period.
• 1. Deciduous dentition - The teeth of the first, or primary dentition.
They are so named because they are shed like the leaves of deciduous
trees in autumn. They erupt into the mouth from about six months to
two years of age. Normally there are 20 total deciduous teeth. Other
non-scientific names for the deciduous teeth include "milk" teeth,
" baby" teeth, and "temporary" teeth.
• 2. Permanent dentition -The teeth of the second, or adult dentition.
Normally, there are 32 permanent teeth and they erupt from 6-21
years of age.

Classification of Teeth
A. Permanent Dentition: As was pointed out, man is a heterodont, which
means that more than one type of tooth is found in the human
dentitions. Each complete quadrant of the permanent dentition
contains eight teeth of differing type and function, as follows:
• 1. Incisors (2) - The incisors are the two teeth of each quadrant which
are closest to the midline. They are named central and lateral incisors.
There functions in mastication are biting, cutting, incising and shearing.
There are four permanent incisors per arch, and a total of eight in the
mouth.
• 2. Canine (1) - The canine is the third tooth from the midline in each
quadrant. Its function in mastication is cutting, tearing, piercing, and
holding. It also is called a cuspid. There are two permanent canines per
arch, and a total of four in the mouth.

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•

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3. Premolars (2) - The premolars are the fourth and fifth teeth from
the midline. They are termed first and second premolars. Their
masticatory role is tearing, holding, and grinding. They are also called
bicuspids. As with the incisors, there are four per arch, and eight total
premolars.
4. Molars (3) - The molars are the sixth, seventh, and eighth teeth from
the midline. They are termed first, second, and third molars. They are
also called six year’s molar, twelve year &, and wisdom tooth, in that
order. Their masticatory function is grinding. There are six permanent
molars per arch, and twelve total permanent molars.
It can thus be seen that there are 16 permanent teeth in a complete
arch, and a total of 32 teeth in the permanent dentition.

B. Deciduous Dentition:
• Each quadrant of man's deciduous dentition contains the following
types of teeth, all of which have a function similar to their permanent
complements:
• 1. Incisors (2), which are named central and lateral incisors.
• 2. Canine (I), or cuspid.
• 3. Molars (2), which are named first and second molars.
• Therefore, there are five deciduous teeth per quadrant. ten per arch.
and a total of twenty in the primary dentition. When compared to the
permanent teeth, the primary dentition contains an identical number
of incisors and canines, but has no premolars and one less molar per
quadrant.

Dentition Periods and Succedaneous
Teeth:
It has been pointed out that man has two dentitions, but three periods
of dentition,since the deciduous and permanent dentitions overlap in
time. These periods are summarized in the following manner:
1. Primary dentition period - That period during which only deciduous
teeth are present, and occurs from approximately six months to six J
ears of age. The primary dentition period ends at about age six, with
the eruption of the first permanent tooth. normally the mandibular
first molar.
2. Mixed dentition period - That period during which both deciduous and
permanent teeth are present. and lasts from approximately 6years to
12 years of age. The mixed dentition period ends and the permanent
dentition period begins at round age twelve. with the exfoliation of the
last deciduous tooth, normally the maxillary second molar.

3. Permanent dentition period- That period when only permanent teeth are
present, and which begins at approximately twelve years of age and continues
through the rest of life.

B. In order for a permanent tooth to erupt into a space where a deciduous
tooth is located, the deciduous tooth must first be shed, or exfoliated.
The natural process by which deciduous roots are "melted away" to
allow for exfoliation is termed resorption.
C. Permanent teeth that replace exfoliated deciduous teeth are called
succedaneous teeth, which simply means "succeeding" deciduous
teeth. Since there are twenty deciduous teeth to be replaced, there
must be twenty succedaneous teeth. The permanent teeth that are also
succedaneous teeth include the incisors and canines, which replace
their deciduous counterparts, and the premolars, which replace the
deciduous molars. Therefore, the only permanent teeth which are not
succedaneous are the molars. It may be said, then, that all
succedaneous teeth are permanent teeth, but all I permanent teeth
are not succedaneous teeth.

• Dental Formulae:
• A. Dental formula - A number and letter designation of the
various types of teeth found in a dentition. The dental
formula indicates the dentition of only one side of the
mouth, but includes both the upper and lower quadrants,
and so must be multiplied by a factor of two to provide the
number of teeth in the entire dentition.
• B. Thus, the dental formula for man's permanent dentition is
as follows:
I-2 : C – 1 : P-2 : M-3
2
1
2
3

• The deciduous dentition of man has the following dental
formula:

I-2 : C – 1 : M-2
2
1
2
• It should be kept in mind that animals other than man may
have differing dental formulae

General Eruption Pattern:
Both the deciduous and permanent dentitions have a general order, or
pattern, of eruption. For the deciduous dentition, this pattern normally
is as follows:
A. Deciduous Dentition: Eruption Sequence
• 1. Mandibular central incisor
• 2. Mandibular lateral incisor
• 3. Maxillary central incisor
• 4. Maxillary lateral incisor
• 5. Mandibular first molar
• 6. Maxillary first molar
• 7. Mandibular canine
• 8. Maxillary canine
• 9. Mandibular second molar
• 10. Maxillary second molar

•

As a general rule, mandibular deciduous teeth normally precede their
maxillary counterparts in eruption. It can also be said that the
deciduous teeth normally erupt in order from the front of the mouth
toward the back, even though the canines in each quadrant normally
erupt after the first molars.

Deciduous Dentition: Normal
Eruption Time
Erruption Age
•
Mandible Order
Maxilla
• Central Incisor
6
1
7 'I2
• Lateral Incisor
7
2
9
• Canine
16
4
19
• First Molar
12
3
14
• Second Molar
20
5
24

Order
1
2
4
3
5

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Permanent Dentition: Normal Eruption Sequence
1. Mandibular first molar
2. Maxillary first molar
3. Mandibular central incisor
4. Mandibular lateral incisor
5. Maxillary central incisor
6. Maxillary lateral incisor
7. Mandibular canine
8. Mandibular first premolar
9. Maxillary first premolar
10. Mandibular second premolar
11. Maxillary second premolar
12. Maxillary canine

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13. Mandibular second molar
14. Maxillary second molar
15. Mandibular third molar
16. Maxillary third molar
As can be seen. the permanent mandibular teeth normally
precede their maxillary counterparts in eruption. as was
also the pattern with the deciduous teeth. If the first
molar's eruption sequence is ignored, the permanent
mandibular teeth exhibit a perfect anterior to poterior
order. However, in the maxillary arch not only is the
firstmolar out of order the canine normally follows both
premolars.

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Eruption Age
Mandible Order
Central Incisor
6-7
2
Lateral Incisor
7-8
3
Canine
9-10
4
First Pre-molar
10-11
5
Second Pre- Molar
11-12
6
First Molar
6-7
1
Second Molar
11-13
7
Third Molar
17-21
8

Maxilla Order
7-8
2
8-9
3
11-12
6
10-11
4
11-12
5
6-7
1
12-13
7
17-21
8

• It should be noted that the eruption sequences and dates
presented here are based on the only studies available,
which were conducted a number of years ago. More
contemporary data has suggested that, in some cases,
these figures may not be entirely correct. It has also been
suggested that there really may not be a "normal“ eruption
pattern which is true for both sexes, and across all racial
groups. In other words, the most common eruption
sequences may occur in only a relatively small percentage
of the total population. However, until the results of
longitudinal studies for North American populations are
available, "old sequences and dates will be used.

Numbering Systems:
• Numbering systems in dentistry serve as abbreviations. Instead of
writing out the entire name of a tooth, such as permanent maxillary
right central incisor, it is much simpler to assign it a number, letter, or
symbol, such as #8 for the universal numbering system. Of the many
systems, the three most commonly used will be described.
• A. Universal Numbering System:
The numbering system which enjoys the widest use today is the universal
system. It employs a different number (1-32) in a consecutive
arrangement for all permanent teeth, and a number-letter (ld-20d) for
each of the deciduous teeth.
1. Permanent Teeth - The universal numbering system assigns a specific
number to each permanent tooth. The upper right third molar is #I, the
upper right second molar #2, and so forth around the entire maxillary
arch to the upper left third molar, which is #16. Since there are no
more permanent teeth in the maxillary arch, the succession drops to
the lower left third molar which is #17, and continues around the entire
mandibular arch where the lower right third molar is #32. For example,
tooth #11 is the permanent maxillary left canine.

2. Deciduous Teeth - The twenty teeth of the deciduous dentition are
numbered in the same manner as are the permanent teeth (1-20),
except that a small (d) is added as a suffix to each number to designate
deciduous. The deciduous upper right second molar is thus #Id, while
the upper left second molar is #10d. The lower right canine, for
example, is #18d.
The most common system in use today for designating deciduous teeth
uses the capital letters A through T. The maxillary right deciduous
second molar is tooth A and the order progresses in the manner used
with the 1-32 system for permanent teeth, so that the mandibular right
deciduous second molar is tooth T.
• B. Palmer Notation Method: Another commonly used numerical and
letter notation scheme for identifying an individual tooth utilizes a
simple symbol, which differs for each of the four quadrants. In addition,
the numbers 1 through 8 are used to identify permanent central
• incisor through third molar in the specified quadrant. Letters A through
E, with the quadrant symbol, are used for the deciduous dentition

FDI System:
The Federation Dentaire Internationale (FDI), the international dental
organization, has introduced a new numbering system, which is an
attempt at standardization throughout the world. Although presently
not in worldwide use, it may be in the future. It is a simple binomial
system, which includes both permanent and deciduous teeth. The first
of the two numbers identifies the quadrant, and whether the tooth is
permanent or deciduous, as follows:
• 1 - Permanent maxillary right quadrant
• 2 - Permanent maxillary left quadrant
• 3 - Permanent mandibular left quadrant
• 4 - Permanent mandibular right quadrant
• 5 - Deciduous maxillary right quadrant
• 6 - Deciduous maxillary left quadrant
• 7 - Deciduous mandibular left quadrant
• 8 - Deciduous mandibular right quadrant

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The second number identifies the particular tooth in the quadrant,
exactly like the Palmer notation method for permanent teeth (1-8).
The deciduous teeth in each quadrant are numbered (1-5), the number
increasing in size from the midline posteriorly.
Examples in notation utilizing the FDI system are as follows:
18 - Permanent maxillary right third molar
27 - Permanent maxillary left second molar
36 - Permanent mandibular left first molar
45 - Permanent mandibular right second premolar
54 - Deciduous maxillary right first molar
63 - Deciduous maxillary left canine
72 - Deciduous mandibular left lateral incisor
81 - Dbciduous mandibular right central incisor

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As review, the first designation in the above list (18) can be analyzed as
follows:
1-The first number indicates that the tooth is located in the permanent
maxillary right quadrant.
8-The second number indicates that the tooth is eighth from the
midline, and
thus is a third molar.

General Oral and Dental Anatomy:
brief definition and description of the various anatomical features of a
normal tooth, and its supporting structures, include the following:
A. Dental Structures:
• 1. Anatomical crown - That portion of the tooth which is covered by
enamel.
• 2. Clinical crown - That portion of the tooth which is visible in the
mouth. The clinical crown may, or may not, correspond to the
anatomical crown, depending on the level of the tooth's investing soft
tissue, and so may also include a portion of the anatomical root. As can
be seen from this description, the clinical crown may be an ever
changing entity throughout life, while the anatomical crown is a
constant entity.

•

3. Anatomical root - That portion of the tooth which is covered with
cementum.
• 4. Clinical root - That portion of the tooth which is not visible in the
mouth. Again, the clinical root is an ever changing entity, and may, or
may not, correspond to the anatomical root. Note: In the dental
literature, the modifying terms "clinical" and "anatomical“ are not
often used with crown or root, but the intended meaning is most often
"anatomical" and so will be used in this manner hereafter.
• 5. Enamel - The hard, mineralized tissue which covers the dentin of the
anatomical crown of a tooth. It is the hardest living body tissue, but is
brittle, especially when not supported by sound underlying dentin.
• 6. Dentin - The hard tissue which forms the main body of the tooth. It
surrounds the pulp cavity, and is covered by the enamel in the
anatomical crown, and by the cementum in the anatomical root. The
dentin constitutes the bulk, or majority, of the total tooth tissues, but
because of its internal location, is not directly visible in a normal tooth.

• 7. Cementum - The layer of hard, bonelike tissue which covers the
dentin of the anatomical root of a tooth.
• 8. Cervical line - The identifiable line around the external surface of a
tooth where the enamel and cementum meet. It is also called the
cemento-enamel junction or CEJ. The cervical line separates the
anatomical crown and the anatomical root, and is a constant entity. Its
location is in the general area of the tooth spoken of as the neck or
cervix
• 9. Dentino-enamel junction or DEJ - The internal line of meeting of the
dentin and enamel in the anatomical crown of a tooth.
• 10.Pulp - The living soft tissue which occupies the pulp cavity of a vital
tooth. It contains the tooth's nutrient supply in the form of blood
vessels, as well as the nerve supply.

Pulp Cavity - The entire internal cavity of a tooth which contains the pulp.
It consists of the following entities:
• a. Pulp canal(s) - That portion of the pulp cavity which is located in the
root(s) of the tooth. and may also be called the root canal(s).
• b. Pulp chamber - The enlarged portion of the pulp cavity which is
found mostly in the anatomical crown of the tooth.
• c. Pulp horns - The usually pointed incisal or occlusal elongations of the
• pulp chamber which often correspond to the cusps, or lobes of the
teeth

1 1. Pulp Cavity - The entire internal cavity of a tooth which contains the
pulp. It consists of the following entities:
• a. Pulp canal(s) - That portion of the pulp cavity which is located in the
root(s) of the tooth. and may also be called the root canal(s).
• b. Pulp chamber - The enlarged portion of the pulp cavity which is
found mostly in the anatomical crown of the tooth.
• c. Pulp horns - The usually pointed incisal or occlusal elongations of the
pulp chamber which often correspond to the cusps, or lobes of the
teeth.

• B. Supporting Structures:
• 1. Alveolar process - The entire bony entity which surrounds and
supports all the teeth in each jaw member.
• 2. Alveolus (Plural - alveoli) - The bony socket, or portion of the
alveolar process, into which an individual tooth is set.
• 3. Periodontal ligament (membrane) - The fibrous attachment of the
tooth cementum to the alveolar bone.
• 4. Gingiva (Plural - gingivae) - The "gum" or "gums", or the fibrous
tissue enclosed by mucous membrane that covers the alveolar
processes and surrounds the necks of the teeth.

Dimensions (Deciduous teeth)
Maxillary(in millimeters)

Primary Maxillary Central Incisor
Primary Maxillary Central Incisor
• Labial Aspect
• Smooth labial surface.
• The M-D diameter is greater than the cervicoincisal length. • Incisal
edge is nearly straight
• Developmental lines are usually not seen.
• The root is cone-shaped with even, tapered sides.
• The root length is greater than crown length than that
of the permanent central incisor.

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Lingual Aspect
Well-developed marginal ridges ,highly
developed cingulum seen
The cingulum extends up toward the
incisal ridge ,practically dividing
into a mesial and distal fossa.
The root narrows lingually ,whereas its
flat surface labially..

Mesial and Distal Aspects
Similar - The measurement of the crown at the cervical third shows the
crown to be wide in relation to its total length.
• The curvature of the cervical line is curving
towards the incisal ridge
• The cervical curvature distally is less than the
curvature mesially
• The root is cone-shaped with even,
tapered sides, apex is blunt
• Usually Mesial has a developmental groove
and distal is generally Convex

The Pulp Cavity
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Consist of 3 slight projections on
incisal border i.e. 3pulp horns
Chamber tapers in M-D diameter cervically,
widest at cervical region Labiolingually
Pulp chamber and Canal are larger than
permanent ones.
No distinct demarcation between
canal &chamber
Pulp canal tapers evenly until ending in apical foramen

Incisal Aspect
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The incisal edge is centered over the main bulk
of the crown and is relatively straight.
The labial surface is much broader and
also smoother than the lingual surface.
The lingual surface tapers towards
the cingulum.

Primary Maxillary Lateral Incisor
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Similar to the central incisor from all
aspects, but its dimensions differ width.
The disto-incisal angles of the crown
are more rounded than those of the central incisor.

Primary Maxillary Lateral Incisor
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The pulp chamber follows the
contour of the tooth, as does the canal
The root has similar shape, but is
longer, thinner and tapering

PRIMARY MANDIBULAR CENTRAL
INCISOR
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Labial Aspect
Flat face ,No developmental grooves
Mesial and distal sides of the crown are
tapered evenly from the contact areas,
with the measurement being less at the cervix
Crown is wide in proportion to its length
The heavy root trunk permanent
maxillary lateral incisor.
The root is long and evenly tapered down
to the apex, which is pointed.
The root is almost twice the length of the crown

Lingual Aspect
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The marginal ridges, cingulum - located easily
Middle
third may hay a
flattened surface/
incisal third
slight concavity
lingual fossa.

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Lingual Convergence of the crown
and root is seen

Mesial Aspect
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The incisal ridge is centered over the center of the root
The convexity of the cervical contours labially
and lingually at the cervical third is Most
pronounced
More pronounced by far than the
prominences found on a permanent
mandibular central incisor.
These cervical bulges are important.
The mesial surface of the root is nearly
flat and evenly tapered; the apex blunt.

Distal Aspect •
• Outline : Opp of mesial
• Cervical line is less curved.
• Developmental depression is evident
on the distal side of the root

Pulp Cavity •
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Widest mesiodistally at the roof
Labiolingually the is widest at the cingulum
Oval in appearance, tapers as it reaches apex
Definite demarcation between chamber and canal

Incisal Aspect
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The incisal ridge is straight and bisects
the crown labiolingually.
A definite taper is evident toward the
cingulum on the lingual side.
The labial surface from this view
presents a flat Mir surface that is
slightly convex, whereas the lingual
surface presents a flattened surface
that is slightly concave.

MANDIBULAR LATERAL INCISOR
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The fundamental outlines are similar
to those primary central incisor.
These two teeth supplement each
other in function.
Somewhat larger in all measurements
except labiolingually, where the two teeth
are practically identical.
Cingulum of the lateral incisor may be
a little more generous than that of the central incisor
Crown root ratio is more in lateral than in central

MANDIBULAR LATERAL INCISOR

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The lingual surface of the crown
between the marginal ridges may be
more concave.
Incisal ridge tends to slope downward distally.
This design lowers the distal contact
area apically, so that proper contact may be
made with the mesial surface of the
primary mandibular canine

Pulp Cavity
• Oval in appearance,
tapers as it reaches apex
• No demarcation between
chamber and canal

Primary Maxillary Canine
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LABIAL SURFACE •
The crown is more constricted at the cervix
in relation to its M-D width.
The mesial and distal surfaces are more convex. It has a
long, well-developed, sharp cusp. •
The cusp on the primary canine is much longer
and sharper ,than permanent
Contact areas are at the same level, which is not
the same in permanent
The Mesial slope of the cusp is longer than the distal slope
The root of the primary canine is long, slender, and
tapering and is more than twice the crown length

LINGUAL SURFACE

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Shows well pronounced enamel ridges
that merge with each other
This lingual ridge divides the lingual surface
into shallow mesiolingual and distolingual fossae
The root of this tooth tapers lingually and
is usually inclined above the middle third

Mesial Aspect
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Similar to that of the lateral and central incisors.•
Difference in proportion is evident.
The measurement labiolingually at the cervical third
is much greater.
* This permits resistance against forces the
tooth must withstand during function.
* The function of this tooth is to punch, tear, and
apprehend food material.

Distal Aspect
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The distal outline of this tooth is the reverse
of the mesial aspect.
Only difference being, Cervical line towards the cusp ridge
is less than on the mesial surface.

Pulp Cavity
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There is a little demarcation between
pulp chamber and the canal.
The canal tapers as it approaches the apex.
Pulp chamber follows the external contour
of teeth.
Central pulpal horn is projecting incisally.

Incisal Aspect
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diamond-shaped
The angles that are found at the contact areas mesially
and distally are more pronounced and less rounded
than those on permanent canines.
Mesial cusp slope is longer than the
distal cusp slope, i.e for Intercuspation
with the lower

MANDIBULAR CANINE
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Little difference in function between the mandibular canine and the
maxillary canine.
The crown is perhaps 0.5 mm shorter,
The root is at least 2 mm shorter .
The M-D measurement at the root trunk is
greater when compared with its M-D measurement
at the contact areas, than is that of the maxillary canine
It is "thicker" accordingly at the "neck" of the tooth.

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The deciduous maxillary canine is much
larger labiolingually
The cervical ridges labially and lingually are not
quite as pronounced as those found on
the maxillary canine.
The greatest variation is the distal cusp slope is
longer than the mesial slope.

Pulp Cavity

• Wide mesiodistally as labiolingually
• No cliff between canal &chamber
• Ends in marked constriction at the apex

PRIMARY MAXILLARY FIRST MOLAR
• Buccal Aspect
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The widest measurement of the crown of
the maxillary first molar is at
the contact areas mesially and distally
From these points, the crown converges toward
the cervix, with the mm at the cervix being
fully 2 mm less than the mm at the contact areas.
* This furnishes a narrower look to the
cervical portion of the crown and root,
than compared to permanent maxillary first molar.

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The occlusal line is slightly scalloped but
with no definite cusp form.
Smooth buccal surface, little evidence of developmental grooves seen.
Relatively smaller than Second molar THE ROOT
The roots of the maxillary first molar are slender and long, and they
spread widely. All three roots may be seen from this aspect.
The distal root is shorter than the mesial one.
The bifurcation of the roots begins almost immediately at the site of
the cervical line (CEJ).
* Actually which includes a trifurcation, and this is a characteristic of
all primary molars, whether maxillary or mandibular. Permanent
molars do not possess this characteristic.
* The root trunk on permanent molars is much heavier, with a greater
distance between the cervical lines to the points of bifurcations a

Lingual Aspect
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The general outline of the lingual aspect
of the crown is similar to that of the
buccal aspect.
The crown converges considerably
in a lingual direction, which makes the lingual
portion calibrate less mesiodistally than
the buccal portion.

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The mesiolingual cusp is the most prominent
cusp on this tooth.
It is the longest and sharpest cusp.
The distolingual cusp is poorly defined;
it is small and rounded.
The distobuccal cusp may be seen,
since it is longer and better developed
than the distolingual cusp.
All three roots also may be seen from this aspect.
The lingual root is larger than the others.

Mesial Aspect
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The dimension of cervical third is greater
than occlusal third
The mesiolingual cusp is longer and
sharper than the mesiobuccal cusp.
A pronounced convexity is evident
on the buccal outline of the cervical third
*characteristic bulge
It actually gives the impression
of overdevelopment in this area

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The mesiobuccal and lingual roots are visible
The distobuccal root is hidden behind
the mesiobuccal root.
The lingual root from this aspect looks
long and slender and extends lingually
to a marked degree.
It curves sharply in a buccal direction
above the middle third

Distal Aspect
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•
•

From the distal aspect, the crown is
narrower distally than mesially;
it tapers markedly toward the distal end.
The distobuccal cusp is long and sharp,
and the distolingual cusp is poorly developed.
The prominent bulge seen from the mesial
aspect at the cervical third does not
continue distally.

•
•

•

The cervical line may curve occlusally, or it may extend straight across
from the buccal surface to the lingual surface.
All three roots may be seen from this angle, but the distobuccal root is
superimposed on the mesiobuccal root so that only the buccal surface
and the apex of the latter may be seen.
The point of bifurcation of the distobuccal root and the lingual root is
near the CEJ and, as described earlier, is typical.

Occlusal Aspect
•
•
•

•
•

•

The crown outline converges lingually.
The crown also converges distally.
Outline however is rectangular, with the
shortest sides of the rectangle
represented by the marginal ridges
The occlusal surface has a central fossa.
A mesial triangular fossa is just inside the
mesial marginal ridge, with a mesial pit in this
fossa and a sulcus with its central groove connecting the two fossae.
A well-defined buccal developmental groove divides the mesiobuccal
cusp and the distobuccal cusp occlusally.

•

•

Supplemental grooves radiate from the pit in the mesial
triangular fossa as follows: -one buccally, one lingually,
and one toward the marginal ridge,with the
last sometimes extending over the marginal ridge mesially.
Oblique ridge.
The distal marginal ridge is thin and poorly developed in
comparison with the mesial marginal ridge

Pulp Cavity
•

Pulp Cavity Consists of a chamber Straight
3 pulpal canals corresponding to 3 roots
• Variations from this basic
design may be present as anastomoses &
branchings.
• 3-4 pulp horns Pulp horn sizes MB>ML>DB

•

•
•
•

Mesio-buccal horn is the largest of
pulpal horns occupying a prominent
portion of pulp chamber.
Mesiolingual pulpal horn is second in
size,quite angular & sharp.
Distobuccal horn is smallest , sharp
& occupies distobuccal angle.
Occlusal view of the pulp chamber resembles
somewhat a triangle with rounded corners

Clinical Significance
•
•
•
•

Narrow occlusal table
Mb pulp horn
Distal surface
Cervical Constriction

Primary Maxillary Second Molar
• Buccal aspect
• The characteristics resemble those of
first permanent molars , but is smaller.
• The buccal view shows two well defined buccal
cusps with buccal development grooves between
them.
• The crown is narrow at the cervix in comparison
with its M-D measurement at the contact areas.

• The crown is much larger then that of first
primary molar
• Roots are slender , are much longer and
heavier ten maxillary first molar
• The point of bifurcation between buccal
roots is close to the cervical line of crown.
• The two buccal cusps are more nearly equal
in size and development than those of
permanent max 1st molar.

•
•
•
•

Lingual Aspect
3 cusps seen
Mesiolingual cusp- large and well developed
Distolingual cusp- well developed more then primary 1st
molar
• Third supplemental cusp- apical to mesiolongual cusp
called the tubercle of carabelli, or fifth cusp
• The cusp is poorly developed and merely acts as a buttress
or supplement to bulk of mesiolingual cusp.

• If the tubercle if carabelli seems to be missing, some traces
of developmental lines or dimples
• A well defined developmental grooves separates
mesiolingual cusp from distolingual and connects with
developmental groove which outlines with fifth cusp
• All three roots are visible from this aspect
• Lingual root is large and thick in comparison with other two
roots
• Approx the same length as mesiobuccal root .

• Mesial Aspect
• The crown has a typical molar outline that resembles that
of the permanent molars very much •
• The crown appears short because of
its width buccolingually in comparison with
its length.
• The crown of this tooth is usually only about
0.5 mm longer than the crown of the first
deciduous molar, but the buccolingual
measurement is 1.5 t 2 mm greater.
• In addition, the roots are 1.5 to 2 mm longer.

• The mesiolingual cusp of the crown with its supplementary
fifth cusp appears large in comparison with the mesiobuccal
cusp.
• The mesiobuccal cusp from this angle is relatively short and
sharp.
• Little curvature to the cervical line is evident.
• Usually, it is almost straight across from buccal surface to
lingual surface.

• The mesiobuccal root from this aspect is broad and
flat. The lingual root has somewhat same curvature
as of 1 molar. • The mesiobuccal root extends
lingually far out beyond the crown outline. • The
point of bifurcation between the mesiobuccal root
and the lingual root is 2 or 3 mm apical to the
cervical line of the crown

• Distal Aspect
• From both the distal and the
mesial aspects, the outline of the
crown lingually creates a smooth,
rounded line,
• whereas a line describing the buccal
surface is almost straight from the crest of
curvature to the tip of the buccal cusp.
• The distobuccal cusp and the distolingual cusp are
about the same in length.
• The cervical line is approximately straight, as was
found mesially

• All three roots are seen from this aspect, although only a
part of the outline of the mesiobuccal root may be seen,
since the distobuccal root is superimposed over it.
• The distobuccal root is shorter and narrower than the other
roots.
• The point of bifurcation between the distobuccal root and
the lingual root is more apical in location than any of the
other points of bifurcation.

• Occlusal Aspect
• From the occlusal aspect, this tooth resembles the
permanent first molar
• It is somewhat rhomboidal and has
four well-developed cusps :
mesiobuccal, distobuccal, mesiolingual,
distolingual, and fifth supplemental cusp.
• The buccal surface is rather flat with the
developmental groove between the cusps less
marked than that found on the
first permanent molar.

Pulp Cavity
• The pulp cavity consist of a pulp
chamber & 3 pulp canals
corresponding to three roots.
• These canals leave floor of chamber at
the mesiobuccal & distobuccal corners
& from lingual area.
• Pulp chamber has 4 pulpal horns,
a fifth horn projecting from lingual aspect of
mesiolingual horn may be present.
• The mesiobuccal pulp horn is largest, pointed &
extends occlusally

• Mesiolingual pulp horn is second
in size, when combined with fifth horn it presents a
bulky appearance.
• Distobuccal pulp horn is third in size, joining
mesiolingual pulp horn as
slight elevation.
• Distolingual pulp horn is shortest & extends only
slightly above occlusal level.

Primary Mandibular First Molar
• It appears strange and primitive
• Buccal Aspect
• The mesial outline of the crown is almost
straight from the contact area to the
cervix
• The distal portion converges toward the cervix more
than usual, so that the contact area extends distally to
a marked degree.
• The distal portion of the crown is shorter than the
mesial portion, with the cervical line dipping apically
where it joins the mesial root.

• • No developmental groove is evident between
them
• The mesial cusp is larger than the distal cusp.
• A developmental depression dividing them (not a
groove) extends over to the buccal surface.
THE ROOT
• The roots are long and slender, and they spread
greatly at the apical third beyond the outline of
the crown.
• The buccal aspect emphasizes the strange,
primitive look of this tooth.

• Lingual Aspect • Mesially, the crown and
root converge lingually to a marked degree
• • Distally, the opposite is true of both
crown & root. • The distolingual cusp is
rounded. • The mesiolingual cusp is long
and sharp at the tip. • The sharp and
prominent mesiolingual cusp is an
• outstanding characteristic • Mesial
marginal ridge is well developed. • Part of
the two buccal cusps may be seen from this

Mesial Aspect
• The mesiobuccal cusp and the mesiolingual cusp
are in view from this aspect, also the
well-developed mesial marginal ridge.
• Cervical line slanted upwards
buccolingually
• The buccal and lingual outlines of the
root drop straight down and are approximately
parallel for more than half their length, tapering
only slightly at the apical third

• The root end is flat and almost square. • A
developmental depression usually extends almost
the full length of the root on the mesial side.

Distal Aspect
• Cervical line does not drop bucally
• Cervical line is almost straight
• Distobuccal cusp and distolingual cusp
are not as long or as sharp as mesial
cusps
• Distal marginal ridges not as straight and well
defined as mesial marginal ridge
• Distal root is rounded and shorter and tapers more
apically

Occlusal aspect
• Crowns outlines converges lingually and also
distally
• Occlusal surface is more nearly rectangular with
shorted sides of the rectange
represented by marginal ridges
• Occlusal surface has central fossa
• Mesial triangular fossa is just inside the mesial
marginal ridge , with a mesial pit in this fossa and a
sulcus with its central groove connecting the two
fossae

• A well defined buccal developmental groove
divides mesiobuccal cusp and distobuccal cusp
occlusally
• Supplemental grooves radiate from the pit in
mesial triangular fossa as follows
• -one buccally , one lingually and one towards the
marginal ridge with last sometimes extending over
the marginal ridge mesially

Pulp Cavity
• Pup cavity contains a chamber and
3 canals
• Mesiobuccal and mesiolingual
canals are confluent and leave
the chamber in the form of a ribbon
• The distal pulp canal projects in ribbon
fashion floor of chamber in distal aspects

• Pulp chamber had 4 pulpal horns
• Mesiobuccal horn- largest and
rounded
• Distobuccal pulp horn-is second ,
but lacks height of mesial horns
• Mesiolingual Horn is third in size and
second in height , while
• Distolingual pulpal horn is smallest
• Occlusal view of pulp chamber is rhomboidal

• Clinical significance
• Cavity preparation
• Mesiobuccal pulp horn

Mandibular second molar
• It has characteristics that resembles those of
Permanent mandibular first molar, although its
dimensions differ
• Buccal Aspect
• IT has a narrower M-D calibration at
the cervical Portion of the crown than
at contact level
• The mandibular first permanent molar, accordingly
is wider at the cervical portion

• The roots are slender and long
• Characteristic flare mesioditally at the
middle and apical thirds
• The point of Bifurcation of the roots starts
immediately below the CEJ

Lingual Aspect
• Two cusps are almost equal
dimensions
• Seen , a short , lingual groove is
• between them
• The cervical line is relatively Straight
• The mesial Portion of the crown seems to be a
little higher then the distal portion , thus appears
tipped distally

Mesial Aspect
• Outline resembles permanent mandibular
First molar
• The crest of contour is more
prominent bucally
• Marginal ridge is high
• The lingual cusp is longer or higher
then Buccal cusp
• Cervical line is regular
• Mesial root is unusually broad and flat with a blunt
and apex sometimes serrated

• The cervical line is regular
• The distal root is almost as broad as the
mesial root and is flattened on distal surface
• The distal root tapers more at the apical end
than does the mesial root

Distal Aspect
• Crown is not as wide distally as it is.
• Mesially, therefore mesiobuccal and distobuccal
cusps from the distal
aspect
• The distolingual cusp appears well
developed and triangular ridge Is seen
over the distal marginal ridge
• The distal marginal ridge dips down more
• sharply and is shorter buccolingually than mesial
marginal ridge

Occlusal Aspect
Occlusal outline is some what rectangular
Three buccal cusps are similar in Size
Two lingual cusps are also equally Matched
Well defined triangular ridges seen
The distal triangular fossa is not well
defined as mesial triangular fossa
• The mesial marginal ridge is better
developed and more pronounced than the distal
marginal ridge
• Supplemental grooves are seen on the slopes of
triangular ridges and in the mesial and distal triangular
fossa
•
•
•
•
•
•

Pulp Cavity
• Pulp cavity is made up of chamber and
usually 3 pulp canals
• Two mesial pulp canals are confluent
as they leave floor of pulp chamber
through A common orifice
• Distal canal is constricted in the centre

• Pulp chamber has 5 pulp horns
corresponding to 5 cusps
• Mesiobuccal and Mesiolinual
Pulp Horns are largest
• Distobuccal horn is smaller then
mesial horns
• The distal horn is shorter and smallest
occupying a position distal to distobuccal
horn

How it differs from Permanent
• In the deciduous molar the M-B,D-B, and the distal
cusps are almost equal in size and development
• The distal cusp of the permanent molar is smaller
than the other two
• Because of the small buccal cusps, deciduous tooth
crown is narrower bucolingually,in comparison
with its mesiodistal measurement, than is the
permanent tooth

Permanent Incisors
• The permanent incisors are the first and second
teeth from the midline, which,
• along with the canines, comprise the anterior teeth
of each quadrant. The incisor
• closest to the midline is termed the central incisor,
while the second tooth from the
• midline is the lateral incisor. This positions the
lateral incisor distal to the central
• incisor and mesial to the canine.

• In size, the maxillary
• incisor crowns are generally larger than
those of the mandibular incisors. In the
• maxillary arch, the central incisor crown is
normally larger than the crown of the
• lateral incisor. However, in the mandibular
arch, the lateral incisor crown and root
• are generally larger than those of the central
incisor, although only very slightly

• The incisors as a group participate in all three of
the major functions of the
• human dentition and have a greater role in
esthetics and phonetics than any other
• group of teeth.
• 1. Mastication - They function by biting, cutting,
incising and shearing, thus
• breaking the food particles into smaller pieces
suitable for grinding.
• .

• 2. Esthetics - Not only do the size, shape,
color, and manner of placement of
• incisors directly contribute to a person's
appearance, but they provide the support
• necessary for the normal profile of the lips
and face.
• 3. Phonetics - They are necessary for the
execution of certain sounds

Labial Aspect
• The mesial margin is straight and meets the incisal
edge at right angle. The distal margin is
shorter and more rounded.
• The distoincisal angle is more
rounded than the mesioincisal angle.
• The labial surface is marked by two
developmental groove and has convexity
in cervical third.
• Maxillary central incisor is the widest anterior
tooth mesiodistally

Lingual Aspect
• The crown profile is same as that of labial surface
except that there is a broad depression
in the central portion called the
lingual fossa and a well developed
cingulum.
• The lingual fossa is bordered by mesial
and distal marginal ridges on the sides Lingual
aspect
and the cingulum cervically.
• The cervical line on labial and lingual surface is
convex apically.

Mesial aspect
• From the mesial aspect the labial
• margin is convex
• The lingual margin is ‘S’ shaped,
being convex near cingulum and concave
in the middle
• Mesial curvature of cervical line (3.5mm) is the
most pronounced compared to any other tooth.
• The cervical line on the mesial and distal surface is
convex incisally

• Distal surface
• is very similar to the mesial surface.
• This outline is also convex, but more rounded than on
the mesial, as is the distoincisal angle.
• The crest of curvature is associated
with the contact area,which is located
• in the incisal third very near the
junction of the incisal and middle thirds,
and so is farther cervically than it is on the mesial.
• Although the cervical half of the mesial and distal
outlines is normally convex, either outline can be
nearly straight, in comparison to the almost always
convex incisal half.

Incisal aspect
• The crown and incisal margin are centered over
root
• Crown profile is almost bilaterally
symmetrical
• The incisal margin of newly erupted teeth show
three elevations called mamelons. They
correspond to the developmental lobes

• Root
 The root is straight and tapers from the cervical
line to the apex giving it a conical shape
 The root ends in a blunt apex.
Average Dimensions in millimeters
Crown Root
Length Length

10.5

13.0

Mesiodistal
Diameter at
Contact
Area
8.5

Mesiodistal
Diameter at
Cervical
Line
7.0

Labiolingual
Diameter at
Crest of
Curvature
7.0

Labiolingua
l
Diameter at
Cervical
Line
6.0

Curvature
of Cervical
Line
M
D

3.5

2.5

Maxillary Lateral Incisor
• The general shape is similar to maxillary central
incisors except that they are shorter and narrower.
• Next to third molars maxillary lateral
incisors are the teeth that show most
variation in crown size, shape and form

• Labial Aspect
• The mesioincisal and distoincisal
angles are more rounded than the
corresponding angles of the maxillary
central incisor
Maxillary Lateral

Distoincisal
angle more
rounded

Mesioincis
al angle
more
rounded

Maxillary Central Incisor

Distoincisal
angle

Mesioincisal
angle

• On the lingual aspect the marginal ridges and
cingulum are more prominent

Prominent marginal
ridges

Prominent cingulum

Labial aspect

Mesial aspect

Lingual aspect

Distal aspect

CANINES
• Canines are very long and stable teeth
There are four canines placed at the corner of the
mouth and hence called the ‘corner stones’ of the
dentition
They have a single pointed cusp (also called
cuspids)
Maxillary canine erupts between 10-12 years and
mandibular canine erupts between 9-10 years of
age

Maxillary Canine
Labial aspect
 The crown of maxillary canine is narrower
mesiodistally than that of maxillary
central incisor.
The incisal aspect has a large cusp with a
pointed cusp tip
It has two slopes (cusp ridges), the mesial slope
being shorter than the distal slope
• The labial surface is smooth and bulky in the
middle because of the labial ridge

•
•
•

Lingual aspect
• The crown and root are narrower lingually
• The cingulum is well developed, large and
sometimes pointed like a cusp
• Occasionally a well developed lingual
ridge is seen that divides the lingual
fossa into mesial and distal lingual fossae
• Heavy marginal ridges are associated with well
formed cingulum and fossae

Mesial aspect
• From the mesial aspect canine looks similar but
bulkier than maxillary central incisor
• Maxillary canine is the widest anterior
tooth labiolingually
• The cervical line curvature is towards the
cusp (incisally)
• The contact area is near the junction of
the incisal and middle third
Mesial aspect

Distal aspect
• Distal surface is very similar to the mesial surface
• The cervical line exhibits less curvature
• The contact are is near the middle third

Incisal aspect
• The labiolingual dimension is greater than the
mesiodistal dimension
• The cusp tip is labial to the centre of the crown
labiolingually and mesial to the centre
mesiodistally
• The labial ridge and the cingulum are very
noticeable from this aspect

• Root – only one
 The root is the longest and strongest of all the
teeth in the dentition
 The mesial and distal surfaces of the root have
developmental depressions.

Crown
Length

Root
Length

10.0

17.0

Mesiodistal
Diameter at
Contact Area

7.5

Mesiodistal
Diameter at
Cervical Line

5.5

Labiolingual
Diameter at
Crest of Curvature

8.0

Labiolingual
Diameter at
Cervical Line

7.0

Curvature of
Cervical Line
M
D

2.5

1.5

Mandibular Canine
•






Labial aspect
Mandibular canines are similar to maxillary canines
except that they are slightly narrower mesiodistally
Mesial outline of the crown is straight and inline
with the mesial outline of the root
The mesial cusp ridge is smaller than the distal
cusp ridge

•




•




Lingual aspect
The lingual surface of the crown is smooth and flat
simulating the surface of mandibular lateral incisor
Cingulum is less prominent and marginal ridges are
less distinct
Mesial and Distal aspects
These aspects are very similar and the cervical line
curves more on the mesial aspect
The contact area on mesial aspect is in the incisal
third and a little higher on the distal third

•




•



Incisal aspect
Like maxillary canine the labiolingual dimension is
more than the mesiodistal dimension
The cusp tip appears inclined in a lingual direction
Root
The root is shorter by 1 or 2 mm
The developmental depression is more
pronounced on the lower canine

Labial
aspect

Lingual
aspect
Incisal aspect

Mesial aspect

Distal aspect

Maxillary Pre- Molars
Introduction
• Premolars are so named because they are placed
between the anterior teeth and the molars
• Premolars assist the canines and the molars in
tearing and chewing food
• Maxillary premolars have two cusps and
sometimes one or two roots
• Maxillary 1st premolar erupts between 10-11 years
and maxillary 2nd premolar erupts between 10-12
years of age

Maxillary 1st Premolar

Maxillary 2nd Premolar

Maxillary 1st Premolar
•

Buccal aspect

• This tooth has two cusps, buccal and lingual cusps.
• The buccal cusp is long with a pointed tip
• resembling the cusp of a canine
• The mesial slope of the buccal cusp is
longer than the distal slope, which is the
opposite of canine
• The buccal surface is convex, showing strong a strong
buccal ridge
• The crown exhibits little cervical line curvature

Lingual aspect
 The crown tapers towards the lingual aspect
 The lingual cusp is shorter than
the buccal cusp
 The lingual cusp is smooth from
the cervical portion to the area
near the cusp tip
 The cusp tip is pointed with mesial and distal
slopes meeting at an angle of about 90 degrees
 Small portion of the buccal cusp can be seen from
this aspect

Mesial aspect
 From the mesial and distal aspect
both the buccal and lingual cusps
are visible
 A well developed mesial marginal
ridge and a mesial marginal
developmental groove is present
 In the middle of the mesial surface is the mesial
Mesial
aspect
developmental depression which continues
beyond the cervical line
 The contact area is near the halfway point (JOM )
3

Distal aspect
There is no developmental depression
or groove on this aspect, instead
it is convex at almost all points
The curvature of the cervical is
less on this aspect
The contact area is near the
junction of occlusal and middle third

Occlusal aspect
The occlusal aspect is roughly hexagonal in shape
The buccolingual dimension of
the crown is much greater than
the mesiodistal dimension
The occlusal surface is circumscribed
by the cusp ridges and marginal ridges



1.
2.
3.
4.
5.
6.

Within the cusp ridges and marginal ridges the
following are present
Central developmental groove
Mesiobuccal and distobuccal developmental groove
Mesial marginal developmental groove
Mesial and distal developmental pit
Mesial and distal triangular fossa
Buccal and lingual triangular ridge

Root
 Most Maxillary first premolars have 2 roots, but
one and three roots can also be seen. Two roots;
buccal and lingual
 The buccal portion of the root resembles canine
•

The root when viewed from the proximal side
shows a big trunk and bifurcation area from where
the buccal and lingual root separate

 A developmental depression is seen on the mesial
aspect of the trunk.

Crown
Length

Root
Length

8.5

14.0

Mesiodistal
Diameter at
Contact
Area
7.0

Mesiodistal
Diameter at
Cervical Line

5.0

Labiolingual
Diameter at
Crest of Curvature

9.0

Labiolingual
Diameter at
Cervical Line

8.0

Curvature of Cervical Line
M
D

1.0

0

Maxillary 2nd Premolar
Buccal aspect
 The maxillary second premolar resembles the
maxillary first premolar in form and function
 The buccal cusp is not as long as that of maxillary
1st premolar
 It is less pointed.
 The mesial slope of the buccal cusp ridge is shorter
than the distal cusp ridge
•

•


•





Lingual aspect
The lingual cusp is more or less the same size as
the buccal cusp
There is greater distance between the cusps
No developmental depression is present nor any
developmental groove crossing the marginal ridge
on the mesial aspect
On the distal aspect there is a developmental
depression which is deeper than the depression on
the mesial surface of maxillary 1st premolar

Occlusal aspect
 The occlusal aspect is more rounded
 The central developmental groove is shorter
 There are multiple supplementary grooves radiating
from the central groove
Root
 Maxillary 2nd premolar has one root, which is
usually as long or a millimeter longer than the root
of maxillary 1st premolar

Buccal aspect

Lingual aspect

Occlusal aspect

Mesial aspect

Distal aspect

Maxillary Molars
• Maxillary molars are the largest teeth in the
maxillary arch. The permanent molars are not
succedaneous teeth because they don’t have any
predecessors. The deciduous molars are still in
place when the first permanent molars erupt at
the age of 6.
• Maxillary First Molar
It has a large crown with four well developed cusps
and occasionally a small fifth cusp. In addition to
the cusps it has three well formed roots; two
buccal and one lingual.

Buccal aspect
 The crown is roughly trapezoidal
• Mesiobuccal and distobuccal
cusps are the two buccal cusps
• Part of mesiolingual and
distolingual cusps are seen
from this aspect as the
distolingual line angle is obtuse
• The buccal developmental groove divides
the two buccal cusps.

Lingual aspect
• General outline of lingual aspect
is reverse of buccal aspect
• The mesiolingual, distolingual
and fifth cusp are the only
cusps seen from this aspect
• Mesiolingual cusp is largest of all the cusps.
Distolingual cusp is small and spheroidal

The lingual developmental groove separates the

lingual cusps
Sometimes a fifth cusp called
the cusp of carebelli may be
present.
When present it attached to the
Lingual
aspect
mesiolingual surface of the mesiolingual cusp.

Mesial aspect
• Mesiobuccal, mesiolingual and fifth cusps are
visible from this aspect also
• Mesial marginal ridge is confluent
• with the mesiobuccal and
• mesiolingual cusp ridges and is
• curved cervically
• The cervical line is irregular,
Mesial
• Curving occlusally
aspect
• The contact area is at the junction of the middle
and occlusal third, closer to the buccal aspect
• A shallow concavity is found just below the
contact are.

Distal aspect
• Distobuccal and distolingual cusps are seen
• The marginal ridge dips sharply cervically
• The cervical line is almost straight

Distal aspect

Occlusal aspect
• The occlusal aspect is roughly rhomboidal in
shape
• Maxillary first molar crown is wider mesially than
distally and wider lingually than buccally
• The elevations and depression on this surface
are:
1. Cusps
• Mesiolingual cusp is the largest followed by
mesiobuccal, distolingual, distobuccal, and
the smallest being the fifth cusp.

•

2.Ridges
 Mesial marginal ridge and distal marginal
ridge
 Oblique ridge
3.
Fossae
 Major fossae: central fossa and distal fossa
 Minor fossae: mesial triangular and distal
triangular fossae

4

Grooves
 Central developmental groove
 Buccal developmental groove
 Lingual developmental groove
 Transverse groove of the oblique ridge
 Distal oblique groove
 Fifth cusp groove
 Supplemental grooves

Pit


Central developmental pit

Occlusal
aspect

• Root
 Maxillary first molar has three roots; two buccal
and one lingual
 The lingual root is long and slender with bluntly
round apex
 Mesiobuccal root is broader and curves distally
while the distobuccal root is narrower at the base
and a lot straighter

 Both the buccal roots are of equal size but smaller
than the lingual root
 The level of bifurcation area is more closer to the
cervical area on the mesial side than on the distal
side.
Crown
Lengt
h
7.5

Root
Length
B L
12 13

Mesiodistal Mesiodistal Labiolingual
Labiolingual Curvature of
Diameter at Diameter at Diameter at
Diameter at Cervical Line
D
Contact Area Cervical Line Crest of Curvature Cervical Line M
10.0

8.0

11.0

10.0

1.0

0

Maxillary Second Molar
 The crown is shorter cervico-occlusally and about
the same width buccolingually when compared
with maxillary first molar
 The distobuccal cusp is not as well developed and
the distolingual cusp is also small. The fifth cusp is
absent
 The roots are as long as, if not somewhat longer
than those of the first molar
 The elevations and depression on the occlusal
surface are similar to that of maxillary first molar.

Buccal
aspect

Lingual aspect

Occlusal
aspect

Maxillary Second Molar

Mesial aspect

Distal aspect

Maxillary Third Molar
 Maxillary third molar varies considerably in size,
shape and position
 It often presents itself as a developmental
anomaly
 Third molar supplements second molar and is also
similar in its design
 All third molars show more developmental
variation than any other teeth in the dentition

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

2

1

1

1 : Mandibular Central Incisor
2 : Mandibular Lateral Incisor

2

Mandibular Central Incisor
Mandibular Central Incisor is the smallest tooth in
the dentition
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

Labial
aspect




It is bilaterally symmetrical
It is the only incisor where both mesioincisal and
distoincisal angles are sharp and at right angles
Both mesioincisal and
distoincisal angles
are sharp

Labial aspect

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

• 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
 The lingual margin is ‘S’ shaped
 The cervical line on the mesial and distal
surface is convex incisally

Mesial
aspect

Distal aspect
• 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.
Labiolingually bigger
than mesiodistally
Bilaterally symmetrical

• Newly erupted teeth show mamelons which
wear off upon mastication

• Root
 The root is single and straight.
 The deflection of the root if present is on the labial
or distal side.

Mesiodistal
Crown Root
Lengt Length Diameter at
Contact Area
h
9.0

12.5

5.0

Mesiodistal
Diameter at
Cervical Line

Labiolingual
Diameter at
Crest of Curvature

3.5

6.0

Labiolingual
Diameter at
Cervical
Line
5.3

Curvature of
Cervical Line
M
D

3.0

2.0

CHRONOLOGY
Contact Area
Man L.I

Appearance of enamel organ

5 m.i.u

First evidence of calcification

3-4 months

Crown completion

4-5 years

I3

Eruption

6-8 years

I3- Incisal third

Root completion

10 years

Mesial

Distal
I3

Mandibular Lateral Incisor




Mandibular lateral incisor is slightly wider
mesiodistally
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
Fan shaped
appearance
Cervical portion
narrower





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

Labial aspect

Lingual
aspect

Incisal aspect

Mesial aspect

Distal aspect

Mandibular Pre-molars
• Mandibular First Premolar
• Mandibular 1st premolar has many characteristics
of mandibular canine
• It functions along with mandibular canine
• It has two cusps and one root
• Mandibular 1st premolar erupts between 10-12
years of age

•

Buccal aspect

 From the buccal aspect a large well formed,
pointed buccal cusp is seen
 The mesial outline is similar to
the distal outline
 The mesiobuccal cusp ridge is
shorter than the distobuccal cusp ridge
(similar to canines)

Buccal
aspect

 The mesial and distal slope of the buccal cusp
sometimes show concavity

Lingual aspect
 The crown tapers and inclines lingually
 The lingual cusp is small,
pointed and nonfunctional and
in some specimens it is no
longer than the cingulum of maxillary canine Lingual
aspect
 Between the mesiobuccal and lingual
lobe is the mesiolingual developmental groove

Mesial aspect







The lingual inclination of the crown can be seen
from this aspect
The lingual cusp is approximately
two thirds the size of the buccal cusp
The mesial marginal ridge has extreme
lingual slope
Mesial
aspect





Mesiolingual developmental groove is present
between the mesial marginal ridge and the
mesiolingual cusp ridge
The mesial and distal contact areas are in the
middle third, the distal contact area being more
wider.

Distal aspect
 Distal marginal ridge is higher
and does not have the extreme
lingual slope
 The cervical line curvature is less curved
Distal
aspect

Occlusal aspect
 The crown converges sharply to the centre of the
lingual surface
 The occlusal surface has two depressions; mesial
and distal fossae
 Most common form of mandibular 1st premolar
shows a mesiolingual depression and mesiolingual
developmental groove

Occlusal aspect

Root
 The mandibular 1st premolar has one root
 The root is approximately (3-4mm)shorter than the
root of mandibular canine but the outline bears a
close resemblance to the canine
 A deep developmental groove is seen on the
mesial aspect on the root
 On the distal aspect there is a shallow depression
devoid of any developmental groove.

Crown
Length

Root
Length

8.5

14.0

Mesiodistal
Diameter at
Contact
Area
7.0

Mesiodistal
Diameter at
Cervical
Line
5.0

Labiolingual
Diameter at
Crest of
Curvature
7.5

Labiolingual
Diameter at
Cervical
Line
6.5

Curvature of
Cervical
Line
M
D
1.0

0

Mandibular Second Premolar
•

•

•

Mandibular 2nd premolar resembles the
mandibular 1st premolar from the buccal aspect
only
The crown assumes two common types. The first
and more common type is the 3-cusp type and the
second is the 2-cusp type
The two differ mainly in the occlusal design

Buccal aspect
 The buccal cusp is shorter with the cusp slopes
presenting less degree of angulations
Lingual aspect
 There may be one or two lingual cusps –
mesiolingual and distolingual cusps
 The cusp(s) are more developed than the lingual
cusp of lower first premolar
 A groove separates the two lingual cusps

•







The crown and root are wider buccolingually
Unlike mandibular 1st premolar the marginal ridge
is at right angle to the long axis of the tooth
More of occlusal surface is visible form the distal
aspect because the distal marginal ridge is at lower
level than the mesial marginal ridge
The contact areas both mesial and distal are broad
and appear higher because of the short buccal cusp

Occlusal aspect
 From the occlusal aspect the 3-cusp type appears
square and the 2-cusp type appears rounded.
• 3-cusp type:- each cusp is separated by deep
developmental grooves forming a “Y” shape in the
centre ,the occlusal surface also includes
a. central pit
b. mesial developmental groove
c. mesial triangular fossa
d. distal developmental groove
e. distal triangular fossa
f. lingual developmental groove
g. supplemental grooves

•

2-cusp type:
- one buccal cusp and one well developed lingual
cusp is present
- a central groove travels in a mesiodistal
direction
and end in mesial and distal fossa (forming ‘H’
shape)
Root


Mandibular 2nd premolar has a single root which
is larger and longer than the root of mandibular
1st premolar



The root is usually wide with a blunt apex

Buccal aspect

Lingual aspect

Occlusal aspect

Mesial aspect

Mandibular Second Premolar
Distal aspect

Mandibular Molars
• The mandibular molars are larger than any other
mandibular teeth.
• They are three in number on each side of the
mandible ,the first, second, and third mandibular
molars.
• The first molar lies posterior to the second
premolar, followed by the second and third molars.
• They perform the major portion of the work of
the lower jaw in mastication.
• Each mandibular molar has two roots, one mesial
and one distal. The third and some second molars
may show a fusion of these roots.

•
•
•

Decrease in size, crowns &
Roots
Roots less divergent
More distal inclination

•

Cusp number

Mandibular First Molar
• Measurements:
Average length 21.5 mm
• Crown length (CL) 7.5mm,
• Root length 14 mm
• Mesiodistal (MD) diameter 11mm
• Buccal Aspect:
the mandibular first molar is the largest tooth in the
mandibular arch.
• It has five well-developed cusps: two buccal, two
lingual, and a distal cusp.
• It has two well-developed roots, one mesial and one
distal. These roots are widely separated at the apices.

Buccal Aspect:
• All five cusps can be seen; the tips of the lingual
cusps can be seen because they are higher than
the others.
• Two developmental grooves appear
on the crown portion; the
mesiobuccal developmental
groove and the distobuccal
developmental groove.
• The mesiobuccal, distobuccal, and distal cusps are
relatively flat.
• The cervical line is commonly regular in outline.

Lingual Aspect:
• Three cusps may be seen: two lingual cusps and
the distal cusp.
• The lingual cusps are high
• enough to hide the buccal cusp.
The lingual developmental
groove is between the
lingual cusps, extending on
the lingual surface.
•

• The mesial outline of the crown is convex. The
crest of contour is higher mesially than distally.
• The distal outline of the crown is straight.
• The cervical line lingually is irregular.
The root bifurcation lingually starts at 4mm below
the cervical line.

Mesial Aspect:
• Two cusps and the mesial root only are to be seen:
the mesiobuccal and mesiolingual cusps and the
mesial root.
• the entire crown has a lingual tilt in relation to the
root axis.
• The buccal outline of the crown
is convex; this curvature outlines
the buccal cervical ridge.
• The cervical line may assume a
straight line.
• The surface of the crown is convex.
• The mesial root curve lingually.

Distal Aspect:
• We see more of the tooth than in the mesial aspect
because there is a distal convergence of the tooth.
• The distal cusp is in the foreground of the crown
portion.
• The distal contact area is placed just
below the distal cusp.
• The distal marginal ridge is short.
The surface is convex.
• The cervical line is straight.

• Occlusal Aspect: outline is hexagonal.
• The MD measurement is greater than BL.
The mesiobuccal cusp is larger than either of the
two lingual cusps, which are almost equal to each
other in size; the distobuccal cusp is smaller than
any one of the other three mentioned, and the
distal cusp is the smallest.

Occlusal
aspect

• The land marks to be identified on this surface are:
(a) Central fossa.
(b) Mesial and distal triangular fossae.
(c) Central developmental groove.
(d) Mesiobuccal and distobuccal
• developmental grooves.
• (e) Lingual Developmental groove.
(f) Central pit
• (g) Mesial and distal marginal ridges.

Mandibular Second Molar
•
•
•
•
•

Measurements:
Average length 20 mm
Crown length (CL) 7mm, Root length 13mm
Mesiodistal (MD) diameter10.5mm
Buccal Aspect:
The crown is shorter and narrower than the first
molar.
There is one developmental groove, the buccal
developmental groove, between the mesiobuccal
and distobuccal cusps.
The roots are inclined distally.

Lingual Aspect:
• The crown and root converge lingually.
• The mesiodistal at the cervix is
always greater than that of
the first molar.
• The contact areas are more
noticeable from the lingual aspect; at a lower level,
especially in the distal, than those of the first
molar.

• Mesial Aspect:
• Except for the differences in measurement,
there are little differences from the
first molar.
• The cervical ridge buccally is less pronounced.
Distal Aspect:
• It is similar to the first molar except
for the absence of the distal cusp
and a distobuccal groove.
• The contact area is centered on the distal surface.

• Occlusal Aspect:
There is considerable difference from the
first molar.
The small distal cusp of the first molar is not
present, as well as an absence of the
distobuccal developmental groove.

Occlusal aspect of Mandibular
Second Molar

Mandibular Third Molar
•
•
•
•
•

Measurements: Average length 18 mm
Crown length (CL)7mm, Root length11 mm
Mesiodistal (MD) diameter10 mm
Buccal Aspect:
vary in outline buccal cusps are
short and rounded.
• shows two roots, mesial and distal,
shorter than the roots of the first and
second molars, and their distal
inclination is greater.
• The roots may be separated or fused.

Lingual Aspect:
The third molar, when well
developed, corresponds
closely to the form of the
second molar except for size and
root development.

• Mesial Aspect &Distal Aspect:
This tooth resembles the
mandibular second molar
except in dimension.
• Occlusal Aspect:
similar to second mandibular
molar; with a more rounded
outline and a smaller buccolingual
measurement

HISTOLOGY
Germ layer

Formative tissue

Tooth structure

Ectoderm

Dental organ

ENAMEL

Dental papilla

DENTIN
PULP

Mesoderm

Dental sac

CEMENTUM
PERIODONTAL
LIGAMENT

Tooth development
Initiation of tooth
Odontogenesis-Factors from first arch
Ones ability acquired maintained by dental
papillary cells

6 wks In utero
• Tooth Buds
• Dental Lamina

Life Cycle of the Tooth
•
•
•
•
•
•
•
•
•

Growth
Initiation
Proliferation
Histodifferentiation
Morphodifferentiation
Apposition
Calcification
Eruption
Attrition

Primary Epithelial band/ 6 week
th

Continuous band of
thickened epithelium

 Roughly horse shoe shaped
 Thickening first seen in ant
midline

• Contd thickening of DL in 10 areas of upper/ lower arch
• Thickenings correspond to position of future primary
dentn

Proliferation
•
•
•
•
•
•

Multiplication of the cells of the initiation stage
Formation of the tooth germ
Cap Stage
formation of the Dental Papilla
Stellate reticulum – Enamel pulp
9-11 weeks

Histodifferentiation
•
•
•
•
•

Bell Stage
Dental papilla
Dental Organ
Dental Sac
Dental Lamina
14th week

Morphodifferentiation
•
•
•
•

Advanced bell stage.
Inner enamel epithelium
Formation of Dentin
Fate of the Dental Lamina
18th week

Apposition
• appositional, additive and regular

Calcification
• Begins at the cusp tips or incisal edges and
proceeds cervically

Stages in tooth growth
Dental lamina and Bud stage
Cap stage
Bell stage[ Early]
Bell stage {advanced}
Formation of enamel
and dentin matrix

Initiation
Proliferation
Hiisto defferentiation
Morpho defferentitiation
Apposition

Formation of Single and Multirooted
Teeth

Formation of multirooted teeth

Eruption of teeth
• Pre-eruptive phase
• Eruptive Phase (Prefunctional)
• Eruptive phase functional

Theories of Eruption
•
•
•
•
•
•

Root Formation Theory
Proliferation of the Hertwig’s Epithelial Root Sheath
Proliferation of the connective tissue of the papilla
Simultaneous growth of the jaw
Pressures from muscular action
Apposition and resorption of bone

Exfoliation of the Primary Tooth
• Pressure on the roots by the erupting
permanent tooth
• Development of osteoclasts
• Successive resorption of tooth root,
cementum, dentin and adjacent bone due to
the action of the osteoclasts.

Clinical significance of morphology&
histology
• Variation of teeth has been an enduring interest to
the clinical practitioner and the laboratory
scientist.
• No two teeth are alike.
• The day-to-day variation of teeth that we see is the
norm.
• It is the odd, peculiar, and strange group of teeth
to which we focus our attention here. They are
called anomalies.

• These few facts about tooth development will
assist us in understanding tooth variation:
• (1) Teeth form from the cooperative interaction of
two germ layers--ectoderm and ectomesenchyme
(a neural crest derivative).
• (2) Enamel is formed from the ectodermal
components.
• (3) Dentin, pulp, cementum, the supporting PDL,
and bone are all derived from ectomesenchyme.

Disturbances in Size
• Microdontia means teeth that are smaller than normal.
Generalized microdontia is a rare condition associated with
uncommon conditions such as pituitary dwarfism."Pegshaped" upper lateral incisors and small third molars are
seen regularly by the practicing dentist. Occasionally, an
upper lateral incisor is missing on one side, peg-shaped on
the other side.
• -Macrodontia refers to teeth that are larger than normal.
Generalized macrodontia is rare, seen infrequently in
conditions such as pituitary gigantism. It can be localized
involving just one or a few teeth. You may occasionally see
the term 'megadontia' used for this condition.
• .....

Disturbances in Number.
• Anodontia is the congenital absense of all teeth, Anodontia
means the failure of teeth to form at all.) In true (or
complete) anodontia, all teeth fail to develop.
• -True anodontia is an extremely rare occurrence. When this
does occur, it is usually part of a more generalized disorder
ectodermal dysplasia, an inherited defect of all
ectodermally derived structures.
• -Partial anodontia is the failure of one or more teeth to
develop. It is much more common than complete
anodontia. Third molars, lower second premolars, and
upper lateral incisors (in that order) are the most common
congenitally absent teeth. When a deciduous tooth is
absent, its permanent successor is usually missing also.)

• Supernumerary teeth are 'extra' teeth. Most (90%) occur in
the maxilla. Their presence in the deciduous dentition is
quite rare. Two terms occasionally used to describe are
polydontia or hyperdontia.
• The most common of all supernumerary teeth is the
mesiodens which is a supernumerary that forms in the
midline between and lingual to the roots of the maxillary
central incisors.
• Most supernumerary teeth do not erupt; they often are
unknown until detected on X-ray films. Fourth molars,
themselves a rare occurrence are infrequently called
'paramolars' or 'distomolars.' Supernumerary teeth occur
less often than do missing teeth.

Disturbances in Eruption.
• -Premature eruption of all of the teeth, either deciduous or
permanent, may suggest an underlying endocrine
dysfunction such as hyperthyroidism.
• A natal tooth seen at birth may be an aberrant 'tooth'
nodule, or it may actually be a deciduous incisor that has
erupted early. The etiology is unknown.
• -Delayed eruption can be due to local or systemic factors.
For one or a few teeth, surgical exposure and--if needed-orthodontic guidance can bring the tooth into its proper
place. X-ray films are useful in evaluating early or late
eruption of teeth.

• Impacted teeth are those that have failed to erupt and
remain buried in the alveolar bone.
The third molars and maxillary canine are
the most frequently impacted teeth,
followed by premolars and supernumerary teeth.
• Ectopic eruption is another type of eruption disturbance;
this occurs when a tooth cannot complete its
eruption because it is blocked by an adjacent
tooth or by a misplaced orthodontic band
usually on a first molar tooth.

• An iatrogenic disease or condition is one that is 'doctorcaused'. If a second molar is inadvertently impacted by a
poorly placed molar band, it is an iatrogenic condition.
These things happen to the best of us. We need to make
these occurrences as few as possible, and to be on the
lookout for them when they do occur.

Disturbances in Shape (The Odd and
the Bizarre)• Dilaceration is a severe bend in the long axis of
the tooth. The bend it located at the junction
between the crown and the root. The bend
can be as much as 90 degrees.
• Dilaceration usually results from trauma
to the unfinished tooth when development
is in progress. Such a tooth in the old literature
is sometimes called a 'hawk billed tooth'.
• -Flexion is a deviation or bend restricted just to the root
portion of the tooth. Usually the bend is less
than 90 degrees. It may be a result of trauma
to the developing tooth.

• -Taurodontism literally means 'bull-like teeth'. Taurodont
teeth are usually molars. They have an abnormally long
pulpal chamber and shortened roots. The pulp chamber has
no constriction near the CEJ as do normal teeth. Clinically
these teeth appear normal. Taurodontism was relatively
common amongst the European Neandertals. It is also
found on occasion in people living today. The implication of
its appearance in modern people is unknown. No treatment
of the condition is necessary apart from due prudence
when doing root canal therapy.

• Dens in dente literally means 'tooth within a tooth'. It is an
uncommon developmental abnormality that primarily
affects maxillary lateral incisors. It is in fact a deeply
invaginated lingual pit with an important clinical
implication: these are very susceptible to caries and they
ought to be restored promptly. Left unattended, these
teeth tend to decay very rapidly. Modern literature will
often refer this condition as dens invaginatus. This is a term
you should know.
• -Supernumerary cusps, or as they are often called, extra
cusps are occasionally found on teeth. We review here the
common types.

• (1) The most common one is the Carabelli Cusp which is
found on the mesiolingual aspect (on the mesiolingual
cusp) of maxillary first molars and maxillary second
deciduous molars.
• -This occlusal landmark can appear with varying degrees of
intensity either as a cusp or pit. These conditions are known
collectively as the Carabelli trait. It is frequently a site of
early dental caries. It is a heritable trait most commonly
seen in European populations. The Carabelli trait is best
understood as a variation, not an anomaly.

• (2) A talon cusp is an extra cusp that resembles an eagle's
talon (a talon is the claw of a bird of prey). A talon cusp
appears as a projection from the cingulum of incisor teeth.
These can interfere with occlusion; however, grinding them
down is a hazardous endeavor. Talon cusps often contain a
prominent pulp horn which is very susceptible to exposure
in the younger patient.
• (3) Very rarely, a similar projection of enamel
can occur on the occlusal surface of the premolar teeth. It
forms a tubercle called a 'dens evaginatus'. Dens evaginitus
can also contain a pulp horn as does the talon cusp
mentioned earlier. Fortunately, these conditions are
infrequent.

• (4) One other variation of the upper first premolar is the
'Uto-Aztecan' upper premolar. It is a bulge on the buccal
cusp that is only found in Native American Indians, with
highest frequencies of occurrence in Arizona. The name is
not a dental term; it comes from a regional linguistic
division of Native American Indian language groups.
• (5) Peg-shaped lateral incisors have already been discussed
above.
• (6) Certain teeth exhibit a variation in the number of roots.

• Incidentally, most root variation is in the distal third of the
root. Sometimes roots can be blunted or shortened. It
tends to occur without apparent cause.
• root resorption and root blunting can be unfortunate
consequence of orthodontic treatment with fixed
appliances
• Extra or fused roots.
• (a.) Upper first premolars usually have two roots; however,
one root is occasionally found in these teeth. More rarely
there are three roots.

• (b.) Lower permanent canines on occasion have a
bifurcation near the apex resulting in two short roots. A
question about this condition has appeared frequently on
Part I National Boards for dental students.
• (c.) Sometimes lower first permanent
molars have three roots. It is the mesial
molar root that is bifurcated.
Clinical articles often consider it an
anomaly. It is just a variation.
Three rooted lower first molars are found
in greater frequency amongst North American Indians with
origins in Asia.
• (d.) In upper third molars, and on occasion with fused
roots, second molars, the roots can be fused together. This
is a variation, not a pathological condition.

• Shovel shaped incisors display enhanced marginal ridges
and present with a distinctive shovel-shaped appearance
on the lingual aspect. They appear frequently in many
persons of Asian origin, including many Native American
Indians. They are especially prominent in Eskimo/Inuit who
are descendants of Siberians about 4,000 years ago.
•

• This next section might best be called 'joined teeth.'
• -Fusion is the union of two teeth by dentin and enamel. The
pulp chambers are often shared; however, they can be
separate. This condition can be differentiated from
gemination (discussed below) by counting the teeth. The
diagnosis can be confirmed if there is a reduction in the
number of teeth that are present in the dental arch. Can
you stand another term? Some authors refer to fusion as
'syndontism'.

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Gemination is the development of two
crowns from a single tooth germ.
It is an incomplete twinning of the
gooth germ. In gemination, there
is a shared pulp and root. Unlike
fusion, the number of teeth is
correct; however, the 'gemination‘
gemination tooth is unusually wide.
Some writers refer to gemination as
'schizodontism'.

• -Concrescence is the joining of tooth roots by cementum. It
occurs after tooth formation is complete. Usually this
condition is 'silent' without clinical significance. When
extracting teeth, however, the prudent clinician will
carefully examine X-ray films of the patient for this
condition. A missed diagnosis can be serious business
during an attempted extraction.
• -A related occurrence is hypercementosis. It is a
consequence excessive cementum deposition. It occurs in
older people often when there are greatly increased or
decreased occlusal forces.

Disturbances in Formation
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Enamel pearls (enamelomas) are small
nodules of enamel found on the root of
the tooth close to or at the
cemento-enamel junction. They are
found most often at the bifurcation or
trifurcation of molars.
They do appear radiographically.
While they can be a problem in
periodontal disease, they should
usually be left alone.

• Their attempted removal can do more harm than good.• Winged incisors are not a disturbance of development, but
rather a special case of rotation of the upper central
incisors.
• It is usually described as a distinctive bilateral rotation to
the mesial which is particularly common amongst Native
American Indians.
• -Enamel hypoplasia can be localized or generalized.
Localized enamel hypoplasia is a visible defect that is
important in archaeology as an indicator of severe sickness
or nutritional deprivation.
• When the insult during tooth formation is brief in duration,
it can be detected histologically in the enamel as a Wilson
line

References
• Wheeler's Dental Anatomy, Physiology and
Occlusion
• Shafer'S Textbook Of Oral Pathology (6Th
Edition)
• Orban's Oral Histology and Embryology
• Woelfel's Dental Anatomy: Its Relevance to
Dentistry
• Internet

Morphology and histology

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