introduction to dental anatomy

3mmar’s dental [email protected] 2015

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Chapter 1

Introduction to dental anatomy & physiology & occlusion

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Chapter (1)introduction to dental

anatomy

(1) Dental nomenclature

Teeth1arrangement of the teeth in oral cavity.2 identify the position , distribution of the teeth.3types & forms of the teeth. 4-tooth identification systems.5-morphological feature (external morphology or macro-anatomy )

or micro-anatomy).6 structural feature (internal composition7 the appearance of the oral cavity.8 tooth surfaces.9 division into third.10 line & point angles.

11 anatomical landmarks of the crown.12 functions of the tooth.

Periodontium1-gengiva.3-cementum.

2-periodontal ligament. 4-alveolar bone.

(2) Human dentition1 primary dentition.2 mixed dentition.3 permanent dentition.

Dental formula..

(3) terms1- shedding3- socket5- self cleansable surface.

2-eruption. 4-crypt.6-calcification.









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Chapter 1

introduction to dental anatomy

(1) teeth1-arrangement of the teeth: teeth are arranged in the oral cavity in the form

of horse-shoe shaped dental arches; one upper , one lower.

the upper dental arch is attached to upper jaw (maxilla) so the teeth in the upper dental arch is called upper teeth or maxillary teeth.

the lower dental arch is attached to lower jaw (mandible) so the teeth in the lower dental arch is called lower teeth or mandibular teeth.

N.B1: maxillary jaw is fixed to the bones of skull while

mandibular jaw is movable , articulate with the skull by tempro-mandibular ligament

Maxillary teeth

Mandibular teeth

mandible

maxilla

1-Dental nomenclature

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2-identify the position & distribution of the teeth in dental arches:

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

the midline: is imaginary vertical plane that divide the arches into two equal right , left segments.

occlusal plane: is imaginary horizontal plane that divide the arches into two equal upper , lower segments

as result of this two lines the oral cavity is divided into four quadrants which are:-1-maxillary right quadrant.

3-mandibular right quadrant.2-maxillary left quadrant.4-mandibular left quadrant.

the total number of primary dentition is 20 teeth & permanent dentition is 32 teeth.

The teeth of both deciduous , permanent dentition are equally distributed between the maxillary , mandibular arches & each arch contains half the total number of teeth which equally distributed in four quadrants.

Maxillary right quadrant Maxillary left quadrant

mandibular right quadrant mandibular left quadrant

N.B: add word (primary) in primary dentition & add word (permanent) in permanent dentition

N.B: the first arch is maxillary right quadrant then follow clock-wise

4 3

21

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Quadrant 1primary maxillary right

quadrant

Quadrant 2primary maxillary left

quadrant

Quadrant 3primary mandibular left

quadrant

Quadrant 4primary mandibular right

quadrant

Quadrant 1 permanent maxillary

right

Quadrant 2permanent maxillary left

quadrant

Quadrant 4permanent mandibular

rightquadrant

Quadrant 3permanent mandibular

leftquadrant

right left

Primary teeth

right left

note: the number of primary teeth in each quadrent is 5 teeth so the total number is 20 teeth.

Permanent teeth

note: the number of permanent teeth in each quadrent is 8 teeth so the total number is 32 teeth.

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3 types & forms of the teeth: According to form , function; teeth are classified into:

1- Incisors: they are 8 in number (4 in each arch) i.e. 2 in each quadrant ; central incisor , lateral incisor.

1 central incisor: is the first tooth centralized next to midline.2 lateral incisor: is the second , its lateral to central incisor.

Function: incising , cutting of the food.

2- canines: they are 4 in number (2 in each arch) i.e. 1 in each quadrant; it’s the third tooth from the midline.

Function: cutting , tearing of the food

3- pre-molars: they are 8 in number (4 in each arch) i.e. 2 in each quadrant ; first premolar & second premolar.

4 first pre-molar: the fourth tooth from the midline.5 second pre-molar: the fifth tooth from the midline.

Function: tearing , grinding of the food.

4- molars: they are 12 in number (6 in each arch) i.e. 3 in each quadrant ; first molar & second molar & third molar.

1 first molar: the sixth tooth from the midline.2 second molar: the seventh tooth from the midline.3 third molar: the eighth tooth from the midline, its called wisdom

tooth.Function: grinding of the food.

the 4 incisors & 2 canines present in dental arch are called anterior teeth. while

the pre-molars & molars are called posterior teeth.

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Third molar (8)second molar (7)

first molar (6)

Second premolar (5)first premolar (4)

Canines (3)lateral incisors (2)central incisors (1)

1 2 34 5

6 7 8

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4-tooth identification systems ( tooth numbering or coding systems ) :

many systems are designed to identify the exact position of the tooth in dental arch.

1-palmer notation system:

o These system utilizes a symbol that represented with bracket having a vertical , horizontal lines, which meet at right angle.

- vertical line: separate right from left teeth.

-horizontal line: separate maxillary (upper) from mandibular (lower) teeth..

-the bracket open toward the quadrant at which the identified tooth is located.

o The permanent teeth are numbered from 1 to 8 in each quadrant , starting the numbering from midline

so: 1 is central incisor , 4 is first premolar , 8 is third molar.

Ex.: is upper right permanent central incisor.

o The deciduous teeth are numbered from A to E in each quadrant , starting the numbering from midline

so: A is central incisor , C is canine , D is first molar , E is second molar.

Ex.: is lower left deciduous first molar.

U.L

L.LL.R

1U.R

2

34

Upper Right

lower Right.

8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 Upper left

8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 lower left

1

Upper Right deciduous Upper left deciduous

lower Right deciduous lower left deciduous

E D C B A

E D C B A

A BCDE

A B C DED

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2-two digit system (the international numbering system) :

o Its bi-numberical system used for tooth identification.

o The tooth to be identified are defined by two digit.

the first digit: indicate the number of the quadrant , written to the left.

The digit from 1 to 4 is used for permanent teeth starting from the

upper right quadrant , directed clockwise manner..

The digit from 5 to 8 is used for deciduous teeth by the same rule.

1

4 3

2 Permanent teeth

78

65 Deciduous teeth

18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28

48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38

55 54 53 52 51 61 62 63 64 65

85 84 83 82 81 71 72 73 74 75

the second digit: indicate the number of the tooth in the quadrant , written to the right.

The digit from 1 to 8 is used for permanent teeth starting from the

midline in each quadrant , directed distally. The digit from 1 to 5 is used for deciduous teeth by the same rule.

The two digit must be pronounced separately.so upper right permanent canine is 13 (one-three)

Permanent teeth

Deciduous teeth

Ex.: 44 is lower right permanent first premolar & 65 is upper left deciduous second molar.

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3-the universal numbering system(the American numbering system) :

For the permanent teeth: the numbers from 1 to 32 are used.

starting from the maxillary right 3rd molar as #1to end at the mandibular right 3rd molar as #32.

* the number is preceded by the sign # to designate this system from two-digit system

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

24 23 22 21 20 19 18 1732 31 30 29 28 27 26 25

Ex.: #3 is upper right permanent firs molar & #9 is upper left permanent central incisor.

Ex: #27 is lower right permanent canine & #20 is lower left permanent second premolar

For the deciduous teeth:

1-the numbers from 1 to 20 are used , the letter d is added as a suffix to each number to designate the deciduous teeth from the permanent teeth.

1d 2 d 3 d 4 d 5 d 6 d 7 d 8 d 9 d 10 d

15 d 14 d 13 d 12 d 11 d20 d 19 d 18 d 17 d 16 d

Ex: #7d is upper left deciduous lateral incisor

2-the alphabet from A to T are another system for deciduous teeth.

A B C D E F G

H I J

T S R Q P O NM L K

Ex: #S is lower right deciduous first molar.

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5- morphological feature of th tooth ( external morphology or macro-anatomy):

each tooth has three anatomical parts: crown & root(s) & neck.

crown:-its coronal part of the tooth covered by enamel.-its variably seen in the mouth according to its extent of eruption.

-there is difference between the part of the crown exposed in the mouth at certain time and the actual size of the crown.

anatomical crown: its part of the tooth which covered with enamel & ends at cervical line.

clinical crown: its part of the tooth which visible in oral cavity (crown or root).

crown

neckroot

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root:-its part of the tooth covered with cementum.-its variably embedded , surrounded & supporting with alveolar bone of the jaw.

anatomical root: its part of the tooth which covered with cementum.clinical root: its part of the tooth which invisible in oral cavity (crown or root).

-according to the number of the roots; teeth may be:

1-single rooted teeth:-incisors , canines.-premolars ( except maxillary first pre-molar).

2 double rooted teeth:root trunk divides at bi-furcation area into 2 roots as:

-maxillary first pre-molar.-mandibular molars.

3 triple rooted teeth:root trunk divides at tri-furcation area into 3 roots as:

-maxillary molars.

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root trunk: its undivided portion of the rootor

it’s the distance from cervical line to furcation area.

orit’s the single root part of multi-rooted teeth.

furcation area: it’s the area where the root branching occurs. in double rooted teeth; its called bi-furcation area.in triple rooted teeth; its called tri-furcation area.

root apex: its free termination of the root.

neck (cervical line ) or ( CEJ):anatomical crown meets the anatomical root at a line known as cervical line.

Single rooted teeth

triple rooted teeth

double rooted teeth

7

76

64

1 23 5

54321

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6-structural feature (internal composion or micro A)each tooth composed of four structures; three hard (dentin , enamel&cementum ) & one soft (pulp).

Dentin:- its represent the main bulk of the tooth.-crown dentin is covered by enamel.-root dentin is covered by cementum.-there are dention-enamel junction (DEJ)

& dentino-cemental junction (DCJ).

Enamel:-its cover the anatomical crown.- it’s the hardest tissue in the body.

cementum:-its cover the anatomical root.-its provide a medium for attachment of PDL.-its meet enamel at cement-enamel junction (CEJ).

Pulp cavity:-its cavity in central part of dentin.-its conform the external outline of the tooth.-it’s the only soft tissue supplying the tooth with blood vessels ,nerves.-its consist of:-

1 pulp chamber: it’s the part of the pulp cavity housedin the crown (coronal pulp).

2 pulp horns: horns-like extensions at the roof of pulp chamber3 pulp orifice: opening in the floor of pulp chamber that connect it by radicular canal.4 root canal: the part of the pulp located at the root (radicular C).

5 apical foramen: it’s the opening of the root canal at the apex; through which the vessels , nerves enter the pulp.

6-sometimes; root canal send some branches which open on lateral surface of the root called lateral canals or (accessory canals)

13

4

5

enameldentin

pulp

Cemen-tum

6

2

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wein’s classification of root canal morphology:-

type 1: one orifice & one foramen.

type 2: two orifice & one foramen.

type 3: two orifice & two orifice.

type 4: one orifice & two foramina.

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7- the appearance of the oral cavity ( surface form of the oral cavity ) :

3-gengiva (gum)

6-floor of the mouth

upon looking into the oral cavity you can see :

1-lips ( upper , lower ) 2-cheek ( buccal )

4-teeth 5-tongue (lingual)

7- palate (roof of mouth) 8-oral cavity proper. 9-vestibule ( labial , buccal )

ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

gengiva

Upper lip

Cheek( buccal )

teeth

vestibule

Tongue ( lingual )

palate

Oral cavity proper

lower lip

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8- teeth surfaces: the crown of the teeth has five surfaces , like a box with

four sides and roof & the surfaces are Identified by The Relationship to other oro-facial structures.

The five tooth surfaces

1- Facial 2- lingual lower teeth

3&4- proximal 5- masticatory

labial (ant.)

buccal (post.)

Mesial toward the

midline

Distal away from

midline

incisal (ant.)

occlusal (post.)

palatal upper teeth

&

The crown of anterior teeth has five surfaces:-

1-mesial: toward the midline. 2-distal: away from the midline

3-labial (facial): toward the lip. 5-incisal: the incising , biting edge.

5- a. lingual: toward the tongue. (lower teeth)b. palatal: toward the palate. (upper teeth)

The crown of posterior teeth has five surfaces:-

1-mesial: toward the midline. 2-distal: away from the midline

3-buccal (facial): toward the cheek. 5-occlusal: masticating surface.

5- a. lingual: toward the tongue. (lower teeth)b. palatal: toward the palate. (upper teeth)

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7- division into thirds:- for purpose of description of the surface regions of the

tooth; the crown & root could be divided into thirds.- each third are named according to the adjacent area to it.- the crown & root can be divided from any aspect horizontally

or vertically.

1 horizontally: ( inciso-cervical & occluso-cervical for the crown ) and ( apico-cervical for the root ).

Crown: incisal third or ( occlusal third ) & middle third& cervical third. root: cervical third & middle third & apical third.

.

2 vertically: the crow only can divide vertically either mesio-distally or

labio-lingually ( bucco-lingually ).& distal third. Mesio-distally:

crown: mesial third & middle third

Labio-lingually (bucco-lingually):crown: labial third ( buccal third )

&

middle third & lingual third.

N.B: in vertical direction; the root divide into half ( M.D half ) or ( labial , lingual half )

MD Lab ling

middle

cervical

cervical

middle

incisal

apical

labi

al

mid

dle

lingu

al

mid

dle

mes

ial

dist

aldi

stal

hal

f

Mes

ial

half

Labi

al h

alf

Ling

ual h

alf

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9- line & point angles:

1-line angle Its angle that’s formed by the union of two surface. Its name is derived from these two surfaces.

2-point angle

Its angle that’s formed by the union of three surface. Its name is derived from these three surfaces.

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10- anatomical landmarks of the crown: in order to study the surface anatomy of the teeth; its important to know the basic anatomical landmarks; there are in the form of elevations & depressions

Anatomical landmarks of the crown

Crown elevations Crown depressions

lobe tubercle ridges

mamelon

cinglum

cusp

Ridges present on facial aspect

Ridges present on ling. aspect

Ridges present on occ. aspect

Labial R

buccal R

cervical R

lingual R

marginal R( M & D )

cusp R ( M & D )

triangular R

lingual Roblique R

transverse R

marginal R ( M & D )

cusp R ( M & D )

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- by age; the mamelons wear down into a flat edge due to the force of biting & the pulp horns obliterated due to formation of secondary dentin.

N.B: the pulp chamber of incisors has 3 pulp horns that corresponding to this 3 mamelons

1-crown elevations

(1) lobe:- its one of primary center of calcification & growth

that fuse together to form the crown duringthe tooth development

- each tooth develops from four lobes in most cases.

The anterior teeth: develop from four lobes ( three labial & one lingual ).

The Premolars: develop from four lobes (three buccal & one lingual ) however

lower 5 may formed from five lobes (three buccal & two lingual ).

The Molars: develop from four lobes (two buccal & two lingual ) however

lower 6 may formed from five lobes (three buccal & two lingual )

N.B1: the teeth which have more than four lobes are lower 5 & lower 6.

N.B2: maxillary lateral incisor & maxillary second , third molars may have three lobes such as ( peg-shaped max. lateral incisor & heart shaped molars )

N.B3: some supernumerary teeth have less than three lobes.

- the mature form of lobes can be presented as mamelons & cinglum & cusp.

1-mamelons:- they are three small rounded projections present in

the incisal third of newly erupted incisors.

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2-cinglum:

- its smooth rounded prominence;making the lingual bulk at the cervical third of the lingual surface of anterior teeth

( incisors + canine ).

3-cusp- its pyramidal projection present on the incisal third of the canine & occlusal third of pre-molars , molars.

(2) tubercle:- it’s a small elevation on the crown resulting from

excessive localized formation of enamel only.

- its present on the palatal aspect of max. E & 6and sometimes on lingual aspect of incisors.

N.B: cusp must be formed of enamel & dentin & pulp horn.

N.B: tubercle differ from cusp as its formed of enamel only.

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(3) ridge:- it’s a linear elevation present on the different surfaces of the crown , its named according to their location or shape.

1. ridges on the facial surface

1-labial ridge (LR):- its vertical linear elevation.

- its present on the labial surface of the canine.

- its result from greater development of middle labial lobe.

2-buccal ridge (BR):

- its vertical linear elevation.

- its present on the buccal surface of the premolars.

- its result from greater development of middle buccal lobe.

3-cervical ridge (CR):

- its horizontal linear elevation.

- its present at cervical third on the facial surfaceof the all teeth.

- its well developed in D & E .

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.

2. ridges on the lingual surface

1-incisal ridge (IR):

- it’s a linear elevation present on lingual aspectin newly erupted incisors.

- by time; it’s will transformed into edgeas attration removes some of incisal enamel.

2-linguall ridge (LR):

- its vertical linear elevation extend from the cinglum to cusp tip.

.- its present on the lingual surface

of the canine..

.

3-cusp ridges (MCR & DCR):

- they are two sloped linear elevations (mesial , distal ). which meet to form an angle at the cusp tip.- they may also be called cusp slopes ( M,D slopes) or cusp arms.-they can be seen from lingual or labial aspect of the canine.

4-marginal ridges (MMR & DMR):

- they are two linear elevations present on mesial & distal margins of the lingual aspect of anterior teeth.

N.B: cusp ridges present also on the occlusal aspect of posterior teeth

N.B: marginal ridges present also on the occlusal aspect of posterior teeth

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3. ridges on the occlusal surface

1-cusp ridges (MCR & DCR)

they are two sloped linear elevations (mesial , distal ) which meet to form an angle at the cusp tip.

- they may also be called cusp slopes or cusp arms.

- hey can be seen from occlusal or lingual or buccal aspect of posterior teeth.

2-marginal ridges (MMR & DMR):

- they are two linear elevations present on mesial & distal margins of the occlusal aspect of posterior teeth.

3-triangular ridge ( R)(:

- Its a linear elevation descend from the cusp tipto the center of occlusal aspect of posterior teeth.

-its formed as two occ. sides of the cusp meets together to form a line angle

N.B: cusp ridges present also on the lingual or labial aspect of the canine.

N.B: marginal ridges present also on the lingual aspect of anterior teeth

LTR

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4-transverse ridge:

- Its a linear elevation result from union of two triangular ridge opposing to each other.

-its transverse the occlusal surface in bucco-lingual direction.

-its present in lower pre-molars.

5-oblique ridge:

- Its a linear elevation result from union oftwo triangular ridge not opposing to each other.

-its cross the occlusal surface in bucco-lingual direction obliquely.

e.g. mesio-lingual & disto-buccal cusps.

-its present in maxillary molars.

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Crown elevations Crown depressions

Linear depression sulcus Circumscribed depression

grooves

developmental

fossa pit

lingual

triangular

fissure

Central (circular)

true

Anatomical landmarks of the crown

fault

Ds

supplemental

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2-crown dpressions

(1) linear

depressions: 1-

developmental groove:

-its shallow , narrow & sharply defined linear depression.

-its denoting to the line of fusion of the primary lobes.

-its present on the labial aspect of anterior teeth &on the occlusal aspect of posterior teeth , may extend buccaly or lingually.

2-supplemental grooves:

- they are irregular auxiliary grooves- they are branched from developmental grooves.- they don’t denoting to line of fusion of lobes-they present on occlusal surface of posterior teeth( 8 followed by 7 have large number of this grooves).

.

3-fissure:

-its a linear depression present inthe bottom of developmental groove.

-its result from incomplete fusion of the primary lobes.

-its defect in enamel so dental caries often begins in a deep fissure.

Ds

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(2) circumscribed depressions:

1.fossa:

- its small concavity depression present on the occlusal surface of posterior teeth & on the lingual aspect of anterior teeth.

- its named according to its location or shape.

1-lingual fossa (LF):

- Its present on the lingual aspect of anterior teeth.

.

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2 mesial & distal triangular fossa :

-they are present on occlusal surface ofposterior teeth distal , mesial to marginal ridges.

.

ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ3 central (circular) fossa :

- its present on the occlusal surface of molars & lower five 3-cusp type.

- its formed by the convergence ofthe triangular ridges as they approach the center of occlusal aspect.

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

N.B: in canine; LF divide by ling. ridge into two lingual fossa

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2.pit:

- this is a pinpointed depression present at the junction or at the ends of developmental grooves.

- its may be true pit or fault pit.

1-true pit:-it’s a pinpointed depression

-present at the bottom of central fossa ( central pit ) or at the bottom of the mesial , distal

triangular fossa ( mesial , distal pits ).

2-fault pit:- it’s a pinpointed depression- present at the end of the

deve. grooves of the molars- its result from incomplete

formation of enamel. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ(3) sulcus:

- its tent or valley shape or U-shape.- its inclines from the cusp tips & meet in developmental grooves.- its present on the occlusal surface of posterior teeth

Fault pit

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2

10-functions of the teeth:1-mastication: it’s the most important function of the teeth. The teeth are designed

in specific form related to the function.

- incisors: have chisel like suitable for incising , cutting of food.- canines: have wedge shape suitable for cutting , tearing of food.- premolas: have two cusps suitable for tearing , grinding of food.- molars: have multiple cusps suitable for grinding of food.

.

2-appearance (esthetic):- well arranged clean teeth with proper alignment give nice appearance to the

face.- teeth give support to facial expression.

3-speech:- the teeth are importance for clear pronounciation of certain

words & production of sound.- teeth , lips & tongue are essential for speech

.

4 growth of jaws:- the teeth play a role in the growth of the jaw by formation of alveolar process due to their eruption.

- the teeth maintain the jaw bones.

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

(2) the periodontium

o Its investing , supporting , attachment & covering system.

o Its consist of: four tissues1two hard tissues: cementum

& alveolar bone.2 two soft tissues : peri-

odontal ligament( P.D.L ) & gengiva

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

gengiva

P.D.L

cementum

Alveolar bone

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2

- Human is di-phyodont since he has two sets of teeth; the preceding set is primary dentition during childhood while the succeeding set is the secondary dentition during the adult hood.

-each dentition predominates for certain time however the replacement of primary dentition by secondary dentition doesn’t occurs for all primary teeth at the same time so there are transitional dentition when some of both primary , secondary dentition are present in the oral cavity at the same time which is called mixed dentition.

1-primary dentition:( temporary or deciduous or predecessor or milky or baby dentition )

- They are 20 teeth; 10 maxillary & 10 mandibular ( 5 teeth in each quadrant ).

- they are present as follow: 2 incisors & 1 canine & 2 molars.

- this dentition begins at 6 monthes & completed at 2 years & end at 6 years. its begins by eruption of deciduous lower central incisor at 6 monthes.

its completed at 2 years by eruption of maxillary second deciduous molar. its end at 6 years by beginning of mixed dentition due to eruption ofpermanent 1st molar which is the permanent tooth erupt in the oral cavity.

2-Human dentition

Central incisor

Lateral incisor

canine

First molar

Second molar

Deciduous dentition

Second molar First molar canine

Lateral incisorCentral incisor

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2

2-mixed dentition: (ugly duckling stage)

-Its a transitional dentition when some of both deciduous , permanent dentition are present in the oral cavity at the same time.

-its begins at 6 years with eruption of permanent 1st molar & end at 12 years with shedding of the last deciduous teeth (usually the upper canine )

3-secondary dentition: ( permanent or succedanuous or adult dentition )

- They are 32 teeth; 16 maxillary & 16 mandibular ( 8 teeth in each quadrant ).

- they are present as follow; 2 incisors & 1 canine & 2 premolars & 3 molars.

- its begins at 12 years by shedding of the last deciduous teeth in the oral cavity & persist for the whole life span of the teeth.

N.B: clinically ; this period is called ugly duckling stage due to

1.diffrence in size , color of the teeth (the deciduous teeth is smaller , whiter than the permanrnt teeth ).

2.presence of edentulous area. 3.inflamation of the gengiva

N.B: not all the permanent teeth replace the deciduous ones , since the permanent molars are group of teeth which are not preceded with deciduous teeth .

there for the permanent dentition can be classified into1 succedenuous teeth: include a group of permanent teeth (incisors

& canine & premolars) that replace the deciduous teeth ( incisors & canine & molars)

2 non-succedanuous teeth: include a group of permanent teeth (permanent molars) that don’t replace any deciduous teeth.They have no deciduous predecessors.

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2

N.B: no premolars in deciduous dentition.

N.B: deciduous molars are replaced by premolars .

N.B: permanent molars have no predecessors .

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2

dental formula :

it indicates the dentitions of only one side ( upper , lower ) of the mouth.

ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

1-shedding (exfoliation) : its process of physiologic loss of deciduous teethto be replaced by their successors .

2-eruption: its process of physiologic axial movement of the tooth towardthe occlusal plane (process of appearance of the tooth into the oral cavity).

In permanent dentition In deciduous dentition

2 1 2 3I C PM M=16

2 1 2 3

2 1 2

I CM=10 2

12

It reads as follow:

-incisors; 2 maxillary & 2 mandibular.

-canines; 1 max. & 1 mand.

-premolars; 2max. & 2 mand.

-molars; 3 max. & 3 mand.

Equal 16 teeth in one side

It reads as follow:

-incisors; 2 maxillary & 2 mandibular.

-canines; 1 max. & 1 mand.

-molars; 2max. & 2 mand.

Equal 10 teeth in one side

3-terms

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2

3 - socket : its bony space in the alveolar containing the root of

the erupted tooth .

3- crypt : its bony space in the alveolar containing the developing un-erupted teeth .

4- self cleansable surface : Those surfaces of the teeth that are smooth , convex ,lubricated by saliva & cleaned by the normal functional action of the tongue, lips, cheeks .

5- calcification : The organic framework of a tooth becomes hard by apposition of calcium and phosphate salts brought in by small blood vessels.

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contact area : ???

maximum of convexity = high of contour = crest of curvature : ???!!!!!

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introduction to dental anatomy

Education