Dr.

Rawa Omar Dental Anatomy Lec(1)

Dr.Gulshang Ahmed

Introduction & Nomenclature

Dental anatomy is the study of the development, morphology, function,
and identity of each of the teeth in the human dentitions, as well as how the teeth
relate in shape, form, structure, color, and function to the other teeth in the same
dental arch and to the teeth in the opposing arch.

Nomenclature
❖ All of the teeth in the mouth together are referred to as dentition.
❖ The teeth in the upper jawbones called maxilla and upper or
maxillary teeth form an arch shape known as maxillary arch.
❖ And those teeth in the lower jawbone which are called the
mandible and collectively with mandibular teeth form the mandibular
arch.

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

Identifying the position and disruption of teeth

To identify the position of the teeth in the dental arch two imaginary lines can be drawn.

Midline: is an imaginary vertical plane that divides the arches into two equal right, and left
segments (also known as left and right quadrants)since each quadrant contains one-fourth
1/4 of all teeth in that dentition.

Occlusal plane: is an imaginary horizontal plane that divides the arches into two equal upper,
and lower segments

As a result of these two lines the oral cavity is divided into four quadrants which are

1. Maxillary right quadrant.

2. Maxillary left quadrant.
3. Mandibular right quadrant.
4. Mandibular left quadrant.

Classification of the Teeth:

According to location classified into

1. Anterior teeth are those teeth in the front of the mouth, specifically, the incisors and the
canines.
2. Posterior teeth are those in the back of the mouth, specifically, the premolars and the
molars.

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

According to form and function classified into:

İncisors:

✓ Named as central incisor (1st tooth) and lateral incisors (2nd tooth) from midline
✓ Function: Biting, cutting, incising and shearing
✓ Total number 8

Canine

✓ Named as canine
✓ 3rd tooth from midline at each quadrant
✓ Function: Cutting, tearing and holding
✓ Total number 4

Premolars (bicuspid):

✓ Named as 1st premolar ( 4th tooth) and 2nd

premolars (5th tooth) from midline
✓ Function: Tearing, holding and grinding
✓ Total number 8

Molars

✓ Named as 1st, 2nd and 3rd molar (6th, 7th and 8th) tooth from midline.
✓ Function: Grinding
✓ Total number 12

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

Types of Dentitions:

➢ One during childhood, called the primary dentition or (deciduous or baby or

milky teeth).
➢ Mixed dentition between primary and permanent period
➢ And one that will hopefully last throughout adulthood, called permanent or
secondary dentition.

Complete Primary dentition:

There are 20 teeth in the entire primary dentition, 10 in the upper maxillary arch and 10 in
the lower mandibular arch (5 teeth in each quadrant).

This dentition is also called the deciduous dentition being replaced sequentially by teeth of the
permanent dentition. The first primary tooth erupts at age of 6 month, the primary dentition starts
at ages of 6 month and end at 6 years with the eruption of the first permanent tooth.

The complete primary dentition has five teeth in each quadrant. The primary teeth in each
quadrant are further divided into three classes: 2incisors ( I ), 1canines (C), and 2molars (M).

The primary incisor closest to the midline between the right and the left quadrants is called
a central incisor; the incisor next to it called a lateral incisor. Next in the arch is a canine, and
continuing around toward the back in each quadrant are two molars: first and second molar.

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

Mixed Dentition:

It’s also called a transition dentition when

some of both deciduous, permanent dentition are
present in the oral cavity at the same time.

It begins at 6 years with the eruption of 1st

permanent tooth and end at 12 years with
shedding of the last deciduous teeth.

Complete Permanent Dentition:

The complete permanent (or secondary) dentition is present in the adult. It is composed of
32 teeth: 16 in the upper maxillary arch and 16 in the lower mandibular arch (8 teeth in each
quadrant).

The first permanent tooth erupts at age of 6 years, the permanent dentition starts at ages of 12
years by shedding of the last primary tooth and continue throughout life.

The complete permanent dentition has eight teeth in each quadrant, which are divided into
four classes: 2 incisors ( I ), 1 canine (C), 2 premolars (PM) and 3molars (M).

The permanent incisor closest to the midline between the right and the left quadrants is called a
central incisor; the incisor next to it called a lateral incisor. Next in the arch is a canine,
followed by a first premolar, then a second premolar. Continuing around toward the back in
each quadrant are three molars: first molar, second molar, and finally third molar.

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

The tooth morphology

• The tooth is made up of two parts: crown and root. The crown is covered with enamel, and
the root portion is covered with cementum. The crown and root join at the cemento-enamel
junction (CEJ), this junction also called the cervical line.
• The entire bony entity which surrounds and supports all the teeth in each jaw member is
known as alveolar process which is enclosed by a fibrous tissue called gum or gingiva.

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

Crown
❖ Anatomical crown: Is that portion of the tooth normally covered by an enamel layer and
ends at cemento-enamel junction of the tooth (portion above the cemento-enamel
junction).

❖ Clinical crown: Is that portion of the tooth which is visible in the oral cavity above the
gum line (portion above the gum).

Anatomic
Clinical
crown
crown

Root:
❖ Anatomic root: Is the portion of the tooth covered by cementum, and extending from the
cemento-enamel junction (portion below the cemento-enamel junction).

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed
❖ Clinical root: Is the portion of the tooth that is not visible in the mouth since it is
covered with gingiva (portion below the gum).

Component of tooth:
The tooth is made up of four tissues: enamel, dentin, cementum, and pulp. The first three of these
(enamel, dentin, and cementum) are relatively hard since they contain considerable mineral
content, especially calcium (so these tissues can also described as calcified).

1) Enamel: Is the white, protective external surface layer of anatomic crown. It is highly
calcified or mineralized, and is the hardest substance in the body. Its mineral content is
95% calcium hydroxyapatite (which is calcified), the remaining substances include 5%
water and enamel matrix.

2) Cementum: Is the dull yellow external layer of the tooth root. The cementum is very
thin. It is composed of 65% calcium hydroxyapatite (mineralized and calcified) and
remaining are organic matter (collagen fiber) and water.
3) Dentin: Is the hard yellowish tissue underlying the enamel and cementum, and makes
up the major bulk of the inner portion of each tooth crown and root. Mature dentin is
composed of about 70% calcium hydroxyapatite, 18% organic matter (collagen fiber), and
12% water, making it harder than cementum but softer and less brittle than enamel. Dentin
is not normally visible except on a dental radiograph, or when the enamel or cementum
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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed
have been worn away, or cut away when preparing a tooth with a bur, or destroyed by
decay.

4) Pulp: Is the soft (not calcified or nonmineralized) tissue in the cavity or space in the
center of the crown and root called the pulp cavity. The pulp cavity has a coronal portion
(pulp chamber) and a radicular portion (pulp canal or root canal). Nerve and blood vessels
enter the pulp through apical foramina. Like dentin, pulp is normally not visible, except
on a dental radiograph or section

Enamel

Pulp chamber
Dentin

Cementum Root canal

The functions of the dental pulp are as follows:

1) Formative: Dentin-producing cells (odontoblasts) produce dentin throughout the life

of a tooth. This is called secondary dentin.

2) Sensory: Nerve endings relay the sense of pain caused from heat, cold, drilling, sweet
foods, decay, and trauma.
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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

3) Nutritive: Blood vessels transport nutrients from the bloodstream to the cells of the
pulp and the odontoblasts that produce dentin.
4) Defensive or protective: Pulp responds to injury or decay by forming reparative
dentin.

Numbering systems

Formulae for Mammalian Teeth

The denomination and number of all mammalian teeth are expressed by formulae that are
used to differentiate the human dentition from that of other species.

The denomination of each tooth is often represented by the initial letter in its name (e.g., I
for incisor, C for canine, P for premolar, M for molar); each letter followed by a horizontal line
and the number of each type of tooth is placed above the line for the maxilla (upper jaw) and
below the line for the mandible (lower jaw). The formulae include one side only with the number
of teeth in each jaw being the same for humans.

The dental formula for the primary/deciduous teeth of only one side
(upper & lower) of the mouth in humans is as follows:

This formula should be read as: Incisor, two maxillary and two mandibular; canine,
one maxillary and one mandibular; molars, two maxillary and two mandibular, or 10 totals on
one side, right or left.
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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

A dental formula for the permanent/ secondary teeth of only on side (upper &
lower) of the mouth human dentition is as follow:

Premolar have now been added to the formula (two maxillary and two mandibular), and
a third molar has been added (one maxillary and one mandibular).

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

Tooth Numbering (Identification) Systems:

In any clinical dental practice, it is important to make and store accurate dental records. To do
so, it is necessary to have a type of code or numbering system for the teeth. These systems
include:

1. The Universal/National Numbering System:

❖ Basically, for permanent dentition the Universal Numbering System uses No. 1 through
32 for the 32 teeth in the permanent dentition,
❖ Starting with 1 for the maxillary right third molar, going around the arch to the
maxillary left third molar as 16;
❖ Dropping down on the same side, the left mandibular third molar becomes 17, and then
the numbers increase around the lower arch to 32, which is the lower right third molar.
Starting

Drop down

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed
❖ While for primary dentition the Universal Numbering System uses 20 letters of the
alphabet from A through T for the 20 teeth in primary dentition.
❖ Starting with A representing the maxillary right second molar, sequentially going around
the arch to the maxillary left second molar as alphabetic J.
❖ Then dropping down on the same side to K for the mandibular left second molar, and then
clockwise around the lower arch to T for the mandibular right second molar.

Starting
Drop down

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

2. The Palmar/Zsigmondy Notation System:

This system utilizes a symbol that is represented with a bracket, having two lines
that meet at a right angle:
A horizontal line representing the occlusal plane, separating maxillary from
mandibular teeth
A vertical line representing the midline, separating right from left teeth

Four different bracket shapes are used to denote each of the four quadrants. The specific
bracket surrounds a number (or letter), which denotes the specific tooth within that quadrant. The
specific brackets are designed to represent each of the four quadrants of the dentition:

Is upper right quadrant

Is upper left quadrant

Is lower right quadrant

Is lower left quadrant

➢ Permanent Dentition:

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

• The permanent teeth are numbered from 1-8 in each quadrant, starting
the numbering from the midline.
• So 1 is central icisor, 4 is premolar, …etc
For example mean mandibular right permanent first premolar.
4

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

➢ Primary Dentition:
• The deciduous teeth are lettered from A-E in each quadrant, starting the
numbering from the midline.
• So: A is central incisor, C canine, ………etc

For example E mean maxillary left primary second molar.

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

3. The World Dental Federation Notation (Ferderation Dentaire Internationale-FDI

System):
Uses two digits for each tooth, permanent or primary.

❖ The first digit denotes the quadrant (right or left) and arch (maxillary or mandibular) as
follow:

Permanent Dentition: the digit from 1 to 4 is used for permanent teeth starting from the
upper right quadrant directed clockwise manner.

1= Permanent dentition, maxillary, right quadrant.

2= Permanent dentition, maxillary, left quadrant.

3= Permanent dentition, mandibular, left quadrant.

4= Permanent dentition, mandibular, right quadrant.

Primary Dentition: the digit from 5 to 8 is used for primary teeth by the same rule.

5= Primary dentition, maxillary, right quadrant.

6= Primary dentition, maxillary, left quadrant.

7=Primary dentition, mandibular, left quadrant.

8= Primary dentition, mandibular, right quadrant.

❖ The second digit denotes the tooth position in each quadrant relative to the midline,
from closest to the midline to the farthest away.
• The digit from 1 to 8 is used for permanent teeth starting from the midline in each quadrant.

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

• The digit from 1 to 5 is used for primary teeth starting from the midline in each quadrant.

❖ Combining the first and second digits, numbers within the range 11 through 48
represent permanent teeth and numbers within the range 51 through 85 represent
primary teeth.

For example, 45 is a permanent mandibular right second premolar since the first digit, 4,
indicates the mandibular right quadrant for a permanent tooth, and the second digit, 5, indicates
the fifth tooth from the midline in the quadrant, namely, the second premolar.

Permanent Dentition

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Dr.Rawa Omar Dental Anatomy Lec(1)
Dr.Gulshang Ahmed

Primary Dentition

And another example for primary tooth, 51 is a primary maxillary right central incisor since
the first digit, 5, indicates the maxillary right quadrant for a primary tooth, and the second digit,
1, indicates the first tooth from the midline in that quadrant, namely, the central incisor

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