Introduction to Dental Anatomy

Introduction to Dental Anatomy for Dental Students

1. New Insight Into
Dental Anatomy
MO'men Gamal AboDaif

2. Introduction to DENTAL ANATOMY
MO'men G. AboDaif











Contents
Part 1: Introduction to Dental Anatomy
-Formation of the Dentition (overview)
-Human Dental Formula
-Teeth Numbering Systems
-Tooth Macro-anatomy
-Tooth Micro-anatomy (Tooth Tissues)
-Teeth Surfaces
-The Crown and Root Thirds
-Line and Point angles
-Landmarks in Human Teeth

2016

New insight into
Dental Anatomy

MO'men Gamal AboDaif
Second year, Dentistry Faculty
October 6 University

Thanks to
My Parents, My Brother and Sisters

3. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
*Human Dentition (Dental Anatomy): It's the science dealing with
-the anatomy of human teeth
-the teeth arrangement in the dental arch
Formation of the Dentitions (Overview)
(Diphyodont)Humans have two sets of teeth in their lifetime:

the period in which there is a mixture of The transition or mixed dentition period:
deciduous and succedaneous teeth present
6 yearsat with the emergence of permanent teeth Begins*
*Ends when all the deciduous teeth have been shed

*The succedaneous and non succedaneous teeth
the teeth that replace the primary teeth *Succedaneous teeth:
(The permanent incisors, canine and premolars)
(The permanent the teeth that don’t preceded by primary teeth *Non Succedaneous teeth:
molars)
Permanent teeth -2 Primary teeth -1
(Secondary) (deciduous, milky and baby)


The teeth erupt after shedding of primary teeth The teeth erupt first in the oral cavity
*Thirty two in number, sixteen in each jaw *Twenty in number, ten in each jaw
and The eruption 6 yearsegin to emerge at B
years except 12 to 13process is completed by
18 to the four 3rd molars which erupt around
years of age25
t egin to emerge into the oral cavity aB
and the child would have 6 monthsabout
his complete set of primary teeth by 2½
to 3 years

4. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
*Arrangement in the Dental Arches:
, one in each jaw archesare arranged in two The teeth
)Arch MaxillaryUpper (-
)Arch MandibularLower (-
The teeth in the The maxillary teeth:
the maxilla, jawupper
The teeth in the The mandibular teeth:
the mandible, jawlower
movable member is the mandibleThe NB:
is maxillaof the two jaws, while the
stationary

The median plane):The midline (The
imaginary vertical line which divides each
arch, as well as the body, into two equal
halves
of each arch are equal halvesThe two *
quadrants termed
The quadrants;
*Four in the mouth, two in each arch
the clockwise in andibular leftMandibular right>Mleft>Maxillary illary right>axM*
direction

*Classes of Teeth:
All the teeth in human dentitions are not of same
shape
*Depending on the form and function, there are
of teeth: four classes
*The incisors> (central and lateral)
*The canines “Cuspids”
*The premolars “bicuspids”> (first and second)
*The molars> (first, second and third)
are found only in the permanent PremolarsNB: *
dentition
anteriors*The incisors and canines are collectively known as the
posteriortively referred to as the *The premolars and molars are collec

5. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Dental Formula
The number and type of teeth present in a dentition can be expressed in the form of a
dental formula
*Different classes of teeth are represented by the first letter in their name
e.g. “I” for incisors, “C” for canine, “P” for premolars and “M” for molars
Each letter is followed by a horizontal line;
*the number above the horizontal line represents the teeth type present in the maxillary
arch
*the number below the line represents the teeth type present in the mandibular arch
Dental Formula for Primary Dentition:
This formula should be read as: incisors, two
maxillary and two mandibular; canines, one
maxillary and one mandibular; molars, two
maxillary and two mandibular
The primary dentition consists of 20 teeth, 10 in each jaw and 5 in each quadrant.
The teeth present in each quadrant from the midline are; central and lateral incisors,
canine, followed by 1
st
and 2nd molars
Dental Formula for Permanent:
This formula should be read as: incisors,
two maxillary and two mandibular;
canines, one maxillary and one
mandibular; premolars, two maxillary
and two mandibular; molars, three
maxillary and three mandibular
The permanent dentition consists of 32 teeth, 16 in each jaw and 8 in each quadrant.
The teeth present in each quadrant from the midline are; central and lateral incisors,
canine, 1st and 2nd premolars, followed by 1st, 2nd and 3rd molars

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6. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Tooth Numbering Systems
Numbering systems in dentistry serve as abbreviations. Instead of writing out the entire name of a tooth,
therefore the most popular systems:

Universal Numbering System:
: uses the numbers from 1 permanent dentition* In the
through 32 for the 32 permanent teeth
maxillary right THIRD molarfor the 1*Starting with
maxillary left THIRD *Going around the arch to the
16as molar
for the 17 *Dropping down on the same side to
mandibular left THIRD molar
, 32*The numbers increase around the lower arch to
mandible right THIRD molarwhich is the




: uses the alphabet from A primary dentition*In the
through T for the 20 primary teeth
maxillary right SECOND molarfor the A*Starting with
maxillary left SECOND *Going around the arch to the
Jas molar
for the K*Dropping down on the same side to
mandibular left SECOND molar
, T*The numbers increase around the lower arch to
mandible right SECOND molarwhich is the

7. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Palmer Notation System (Zsigmondy System)
*In this system, the mouth is divided into four sections called quadrants
Permanent Dentition*Beginning with the central incisor, the teeth are numbered from 1 through 8 for the
THIRD molar in each quadrant
Primary Dentition*Beginning with the central incisor, the teeth are lettered from A through E for the
SECOND molar in each quadrant
NB:*The numbers sit inside an (L or bracket) shaped symbol used to identify the quadrant
*It uses four different bracket shapes to differentiate each of the four quadrants as follows:
- Upper right
- Upper left
- Lower right
- Lower left

8. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
The World Dental Federation notation (the Federation Dentaire International or FDI System)
(Two Digit System)
Permanent Teeth
The first digit indicates the quadrant number (1 to 4)
*Quadrant Numbers
1 =Maxillary right 2 =Maxillary left
3 =Mandibular left 4 =Mandibular right
The second digit indicates the tooth number within the
quadrant (1 to 8)
*Start with number 1 at the midline for the central incisor
to number 8 for the third molar
NB: The digits are pronounced separately. For example:
"Two-five" (25) is the permanent maxillary left second
premolar
"Four-two" (42) is the permanent mandibular right lateral
incisor

Primary Teeth
The first digit indicates the quadrant number
(5 to 8)
*Quadrant Numbers
5 =Maxillary right 6 =Maxillary left
7 =Mandibular left 8 =Mandibular right
The second digit indicates the tooth number within the
quadrant (1 to 8)
*Start with number 1 at the midline for the central
incisor to number 8 for the third molar
NB: The digits are pronounced separately. For
example:
"Eight-three" (83) is the primary maxillary left second
premolar
"Six-five" (65) is the primary mandibular right lateral
incisor

9. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Question **Using the FDI numbering system, Identify which tooth is Known with number (……)?
We must write it's:
the the quadrant (right or left) from -arch (maxillary or mandibular) 3-dentition (permanent or primary) 2-1
first digit
the second digittooth type (central, canine…ect) from -4
NB: *Numbers within the range 11 through 48 represent permanent teeth
For example, 48 is a permanent mandibular right third molar
-The first digit (4) indicates the mandibular right quadrant for a permanent tooth
-The second digit (8) indicates the eighth tooth from the midline in that quadrant, namely, the third molar

*Numbers within the range 51 through 85 represent primary teeth
For example, 51 is a primary maxillary right central incisor
-The first digit (5) indicates the maxillary right quadrant for a primary tooth
The second digit (1) indicates the first tooth from the midline in that quadrant, namely, the central incisor-
*If the Universal number for a tooth were 32, the World Dental Federation number would be 48.
All of the tooth numbers are shown in the next Table

10. Introduction to DENTAL ANATOMY
MO'men G. AboDaif

11. Introduction to DENTAL ANATOMY
MO'men G. AboDaif


























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12. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
The Macro-anatomy of
the Teeth
-the teeth can be divided into
crown and root which are joined
-the cervical line (Cementoat
Enamel junction)







: it's the part of the tooth covered with Enamel and visible in the Cronal Portion-1
oral cavity
*The crown of different teeth vary in
shape and size as their function
*The crown is formed of
-incisal ridge (edge) in Incisors
-cusps; Single cusp in Canines
Tow (or more) cusps in Premolars
Three (or more) cusps in Molars
Incisal ridge and cusps are the NB:
cutting surface on tooth crowns

where it is constant : the part of the tooth covered with enamel,Anatomical Crown
in length throughout life
appears in the oral cavity regardless to its : the part of the tooth which Clinical Crown
covering tissue, where it varies according to the gum's (gingiva) position so its length
changes throughout life

13. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
: it's the part of the tooth covered by Cementum and invisible in the Root Portion-2
oral cavity

: the part of the tooth covered by cementumAnatomical Root
the part of the tooth which is invisible in the oral cavity and lies within : Clinical Root
the alveolus, it may change throughout life

*the root may be
–Single root as anterior teeth
(Incisors and Canines) and
most premolars
-Double roots (with
bifurcation) as the lower
molars and upper first
premolar
-Triple roots (with trifurcation)
as the upper molars



*In newly erupted tooth (baby and young people), the clinical crown is shorter than
the anatomical one,
Because part of the anatomical crown
added to the anatomical root
*In old people (when gingival recession
occurs), the clinical crown is longer than
the anatomical one,
Because part of the anatomical root
added to the anatomical crown
*The clinical crown equals the
anatomical one when the gingiva at the cervical line level.
NB: The terminal part of the root is called the root apex where the apical foramen is
present
alveolar bone (jaw *The root is surrounded, embedded and supported with the
bone) which called (alveolar process)
* The tooth is attached to the alveolus by a strong ligament known as the
Periodontal Ligament.
*The soft fibrous tissue which covers the alveolar bone and surrounds the necks of
the teeth is called the Gingiva (Gum).
*The bony space in the alveolar bone in which the roots of the erupted tooth is
found is called Socket.

14. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
The Microanatomy of the Tooth
Dental Tissues
*The tooth is composed of two types of tissue (Hard tissue and Soft tissue)
*There are three hard tissues enamel, cementum and dentin
*There are one soft tissue is consisted in the Pulp

Hard Tissues
1- Enamel: It's the covering surface of the crown of the tooth
NB:
*The enamel is the hardest tissue of
to the teeth and whole body
exerted withstand various forces
during mastication
*The thickness of the enamel varies
according to
-the different types of the tooth
-the different parts of the same tooth
It is thick over the tip of the crown
and becomes thinner until ends at the
cervical line.


2- Cementum: It's the covering
surface of the root of the tooth
NB:
enamel -(the cementofrom the cervical line to the Root apex *The cementum extends
junction to the apical foramen)
*The cementum is thickest near the root apex (apical foramen of the bifurcation area
of the root)
the periodontal ligament*The cementum gives attachment to
)the periodontal ligament(The tooth is attached to the bone through


3- Dentin: The main portion of the tooth
NB:
*The dentin lies beneath –the enamel in the crown
-the cementum in the root
*The dentin –forms the major portion of the tooth
-provides basic shape to the tooth
-covers the pulp cavity

15. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Soft Tissue
*Pulp:
The soft inner structure of the tooth which contain nerves, blood vessels and
lymphatics
NB:
*The pulp is present in the pulp cavity
(The pulp cavity occupies the central
portion of the tooth)
*The pulp contain nerves, blood vessels and
lymphatics
*The pulp can be divided into Cronal pulp
and Radicular pulp


The cronal pulp (Pulp Chamber)
- is situated in the center of the crown of the
tooth
(Pulp horns: The extension of the pulp in the cusps)

The radicular pulp (Pulp Canal)
* is situated within the root of the tooth
*its shape follows that of the root
*open through the apical foramen (formania)
*Apical foramen -is small opening at the root apex
-communicates the pulp with connective tissue of the periodontium
It is possible for the pulp canal to have two or more branches which make their exits
at the apical end with number of apical foramina

16. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Surfaces of the tooth
*The teeth are divided into
-Anterior teeth (the incisors and the canines)
-Posterior teeth (the premolars and molars)

A. The OUTER SURFACES
the tooth facing The surface of Labial surface:*
the lips
(This term is used for the anterior teeth)
The surface of the tooth Buccal surface:*
facing the cheeks
(This term is used for the posterior teeth)
: the surface toward the faceFacial surface*
The labial and buccal surfaces are referred to
as the facial surfaces


B. The INNER SURFACES
The surface of the teeth facing the palate *Palatal surface:
(This term is used for the Maxillary teeth)
: The surface of the tooth facing the tongue*Lingual surface
(This term is used for the Mandible teeth)

C. APPROXIMATING SURFACES OF TEETH
The side of the tooth facing the adjacent tooth in the same dental arch Proximal surface:*
a proximal surface which present towards the midline Mesial surface:-
(facing the back of ent away from the midline: a proximal surface which presDistal surface-
the mouth)
EXCEPTthe mesial surface of a tooth touches the distal surface of an adjacent tooth NB:
*Between the central incisors where the mesial surface of one central incisor faces another
mesial surface.
*the distal surface of the last molar does not approximate another tooth.
The area on a proximal surface of the crown that *Contact area:
contacts the adjacent tooth in the same arch
ormally have two contact areas All teeth in each quadrant n-
of course, has no distal contact areawhich, last molarthe except

D. BITING SURFACES
The cutting surface which is used in mastication :*Incisal ridge /edge
(cutting foods)
(This term is used for the anterior teeth)
So, the anterior teeth have four surfaces and the fifth surface is a ridge
*Occlusal surface:
The cutting surface which is used in mastication (grinding foods)
(This term is used for the posterior teeth)
So, the posterior teeth have five surfaces

17. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Division of a tooth into Thirds:
In order to facilitating the location of various areas within specific surfaces of a tooth, the
tooth could be divided into thirds in three directions:

A-Horizontally (Occlusocervically):
The crown is divided into:
1-Incisal third (for anterior teeth)
Occlusal third (for posterior teeth)
2-Middle third of the crown
3-Cervical third of the crown
The root is divided into
1-Cervical third of the root
2-Middle third of root
3-Apical


B-Mesiodistally: The tooth is divided into:
1-Mesial third
2-Middle third
3-Distal third

C-Labio-or buccolingually:
The tooth is divided into:
1-Labial (for anterior teeth)
Buccal third (for posterior teeth)
2-Middle third
3-Lingual third

18. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Line angles and point angles
The Line angles: They are imaginary lines formed by the junction of two surfaces.
NB: They are named according to the names of the two joining surfaces
Line angles of Anterior Teeth
1-Mesio-labial 2-Mesio-lingual
3-Disto-labial 4-Disto-lingual
5-Labio-incisal 6-Linguo-incisal
Line angles of Posterior Teeth
1-Mesio-buccal 2-Mesio-lingual
3-Disto-buccal 4-Disto-lingual
5-Mesio- occlusal 6-Disto-occlusal
7-Bucca-occlusal 8-Lingua-occlusal
NB: There are 6 line angles in anterior teeth and 8 line angles in the posterior teeth, as there
is no line angles proximally in the anterior teeth.
The point angles: They are formed of the junction of three surfaces.
NB: They are named according to the names of the three joining surfaces.
Point angles for Anterior Teeth
1-Mesio-labio-incisal
2-Mesio-linguo-incisal
3-Disto-labio-inicisal
4-Disto-linguo-lincisal
Point angles for posterior Teeth
1-Mesio-bucco-occlusal
2-Mesio-lingui-occlusal
3-Disto-bucco- occlusal
4-Disto-linguo- occlusal
Landmarks in Human

19. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Teeth (Surface anatomy of teeth)
Crown Elevations
Cusp:
)elevation (pyramidal shaped prominent roundedIs
–on the occlusal surface of the posterior teeth
- forms the tip of the canine (Cuspid)
developmental lobeEach cusp represents a calcified * NB:
extending four cusp ridgesEach cusp has *
In different directions (mesial, distal, facial and lingual) from its tip

Tubercle:
elevation in the teeth crown small roundedIs a
extra formation of enamel*produced by an
)E (Primaryand 6 (Permanent) *mostly present in the
*deviations from the typical form



):cingula –(Plural Cingulum
convex rounded bulkIs the
the anterior teethIn the cervical third of the lingual surface of *
*It represents the lingual lobe


depositionIt is the first site of calcium Lobe:
Each tooth begins to develop from four or more growth centers, these centers are
known as Developmental lobes
*The lobes grow until they fuse
*The union of these lobes is marked by lines on the tooth called developmental
groove which can be seen on the tooth after it has erupted
*The lobes are represented by
–the mamelons of anterior teeth
-the cusps of posterior teeth
-the cingulum in the cervical third of the lingual surface of the anterior teeth

20. Introduction to DENTAL ANATOMY
MO'men G. AboDaif

Ridge: Any linear elevation on the surface of tooth
*Is named according to its location or shape;

Is the linear elevation that forms Marginal ridge:
*the mesial and distal boundaries of the occlusal
surfaces of the posterior teeth
*the mesial and distal boundaries of the lingual
surfaces of the anterior teeth

Triangular ridge: Is linear ridge\
Descend from the tips of cusps of the
posterior teeth toward the central part
of the occlusal surfaces
NB: They are so named because the
slopes of each side of the ridge are
inclined to resemble two sides of a
triangle

Transverse ridge: is a union of
two (buccal and lingual)
triangular ridges which
transversely cross the occlusal
surface of a posterior tooth
*usually found on the lower
first premolar

Oblique ridge: Is a ridge formed by the union of the triangular ridges of two cusps
Not facing each other
*Crossing obliquely the occlusal surface of the maxillary molars from the
mesiolingual cusps to distobuccal cusps

21. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Incisal ridge: found on the incisal surface of anterior teeth
Labial ridge: found on the middle third of labial surface of canines
Buccal ridge: found on the middle third of buccal surface of premolars
Cervical ridges: Is a ridge found on the cervical third of the facial surface of all teeth
Lingual ridge: found on the middle third of lingual surface of canines.
*It is more developed in upper canine than lower one








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22. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Crown Depressions
Groove: Linear depression in the surface of a tooth
It could be:
Developmental (primary) groove: Shallow linear
groove between the primary parts of the crown or root
Supplemental (secondary) grooves: Shallow linear
groove which branch from the developmental grooves
*usually when they increase, they appear as wrinkles on the occlusal surface
Fissure: very narrow cleft at the depth of any groove
*caused by the incomplete fusion of enamel during tooth development
*Tooth caries begins in the deepest part of a fissure


Fossa: Rounded depression or concavity in the
surface of a tooth
*Is named according to its shape and location:
Central Fossa: *present on the occlusal surfaces of the
molars
*running mesiodistally
*They are formed by the meeting of the developmental grooves on the occlusal surface
Triangular fossa: *present on the occlusal surfaces of the posterior teeth
*mesial to the distal marginal ridge> Mesial Triangular Fossa
*distal to the mesial marginal ridge> Distal Triangular Fossa
Lingual fossa: on the lingual surface of the incisors

Pit: Small pinpoint depression represent the deepest point of a fossa
*So, it is located at the junction of developmental grooves or at their terminals

23. Introduction to DENTAL ANATOMY
MO'men G. AboDaif
Sulcus: broad V-shaped depression or valley between
cusps and ridges
*running mesiodistally
*has a developmental groove in its bottom
NB: we must differentiate between:
Groove: linear depression
Fossa: Rounded depression
Sulcus: V-shaped depression like a trough or a valley


Other Terms:
Height of contour (Crest Of Curvature): the maximum convexity of the surface
*Its level differ from the facial to the lingual surfaces









To Be Continued Inshallah…