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Chapter 3
Lecture 2
Tooth identification system :
Numbering systems :
Why is code or numbering system important?
1- making or filling of accurate dental records is an important
task in any dental practice
2- simplifying the charting of tooth information
Numbering systems (USA):
 Universal numbering system :
 uses numbers 1 – 32 for the 32 permanent
dentition ( fig 3-1 & table 3-1)
Going (clockwise) :
1. number 1 for the maxillary right 3rd molar
2. going around the arch to the maxillary left 3rd molar as
number 16
3. dropping down on the same side the left madibular 3rd
molar as number 17
4. around the lower arch the mandibular right 3rd molar
as number 32
 uses alphabet (A-T) for the 20 primary dentition
Going (clockwise) :
1. letter A represents the maxillary right 2nd
molar
2. going around the arch the maxillary left 2nd
molar as letter J
3. dropping down on the same side the
mandibular left 2nd molar as letter K
4. around the lower arch the mandibular right
2nd molar as letter T
The palmar notation system : ( table 3-1 important : ) )
 Utilize 4 brackets ( to denote the quadrant) which
surrounds a number (denoting the tooth in that quadrant )
 As facing the patient :
Upper right ,
lower right
Upper left
lower left
,
Note : Upper = maxillary , lower = mandibular
Numbering Permanent teeth :
Each quadrant is numbered as follows :
 From number 1 (nearest to the arch midline ) to number
8
( farthest from the arch midline )
 So 1 will be the central incisor to 8 the 3rd molar ( in any
quadrant
Example
1
lower right central incisor
2
upper right canine
5
lower left 2nd premolar
Numbering Primary teeth :
The same way but we use alphabet from A to E for each arch
( see table 3-1 very important : ) )
International numbering system : (FDI)
Uses 2 digits for each tooth primary or permanent :
1. the first digit denotes : quadrant ( right or left ) and Arch
( maxillary or mandibular) and dentition ( permanent or
primary)
2. second digit denotes the tooth position relative to the midline
from closest to furthest
Examples ( see table 3-1)
PERMANENT TEETH:
1st digit
1 = maxillary right
2nd digit
1 = central incisor
2 = lateral incisor
Etc…
8 = 3rd molar
2 = maxillary left
1 = central incisor
2 = lateral incisor
Etc…
8 = 3rd molar
3 = mandibular left
1 = central incisor
2 = lateral incisor
Etc…
8 = 3rd molar
4 = mandibular right
1 = central incisor
2 = lateral incisor
Etc…
8 = 3rd molar
tooth
11: permanent
maxillary right
central incisor
12 : permanent
maxillary right lateral
incisor
18 ; permanent
maxillary right 3rd
molar
23 : permanent
maxillary left canine
25 : permanent
maxillary left 2nd
premolar
36 :permanent
mandibular left 1st
molar
34 : permanent
mandibular left 1st
premolar
41 : permanent
mandiblar right
central incisor
43 : permanent
mandiblar right
canine
PRIMARY TEETH
1st digit
5 = maxillary right
6 = maxillary left
2nd digit
1= central incisor
2= lateral incisor
Etc…
5 = 2nd molar
1= central incisor
2= lateral incisor
Etc…
5 = 2nd molar
Tooth
51 :primary
maxillary right
central incisor
55 : primary
maxillary right 2nd
molar
63 : primary
maxillary left
canine
62 : primary
maxillary left lateral
incisor
7 = mandibular left
1= central incisor
74 : primary
2= lateral incisor
mandibular left 1st
Etc…
molar
nd
5 = 2 molar
75 : primary
mandibular left 2nd
molar
8 = mandibular right 1= central incisor
81 : primary
2= lateral incisor
mandibular right
Etc…
central incisor
nd
5 = 2 molar
83 : primary
mandibular right
canine
The numbers in the range from 11 – 48 = permanent teeth
The numbers in the range from 51 – 85 = primary teeth
PARTS OF THE TOOTH
Tissue of the tooth (fig 3-2)
The tooth is made up of 4 tissues :
2 visible tissues in an intact extracted tooth : enamel and
cementum
1. Enamel : is white protective external surface of the anatomic
crown
 Highly calcified or mineralized ; ( 95% calcium
hydroxyapatite ) which is calcified and inorganic
 4% water and 1% enamel matrix (organic)
 the hardest tissue in the body
 developes from the enamel organ ectoderm
 is a product of specialized epithelial cell called Amelobalsts
2. Cementum : the dull yellow external layer of the tooth root
 very thin next to cervical line
 65% calcium hydroxyapatite which is calcified and
inorganic and 23% organic matter ( collagen fibers ) and
16% water making it as hard as bone
 Developes from the dental sac ( mesoderm)
 Produced by cells called Cemntoblasts
 Cementoenamel junction : separates the enamel of
the anatomic crown from the cementum of the
anatomic root
 Also called cervical line denoting that it surrounds the
neck of the cervix
3. Dentin : hard yellowish tissue underlying the enamel and
cementum making up the major bulk of the inner portion of each
tooth crown and root
 It extends internally from the pulp cavity in the center of the
tooth outward to inner surface of the enamel ( on the
crown) or cementum ( on the root )
 Normally is not visible except
Dental radiograph
Sectioned tooth
Badly worn tooth or decayed
 Composed of 70% calcium hydroxyapatite ( calcified and
inorganic)
 18% organic matter ( collagen fibers)
 12% water making it harder than cementum but softer
than enamel
 Develops from embryonic dental papilla ( mesoderm)
 The cells that produce dentin called odontoblasts located at
the junction between the pulp and dentin
 Dentinoenamel junction : inner surface of the enamel
cap where the enamel joins the dentin ( onley visible in
a cross section or when preparing tooth for restoration)
 Cementodentinal junction or the dentinocemental
junction : inner surface of the cementum lining the root
( onley visible in a cross section or when preparing
tooth for restoration)
4. Pulp : soft (not calcified) tissue in the cavity or space in the
center of the crown and root called the Pulp cavity
Pulp cavity has :
 Coronal portion ( pulp chamber)
 Root portion ( pulp canal)
The pulp cavity :
 Surrounded by dentin, except at a hole or holes near the root
tip( apex) called Apical foramen, plural foramina
 Normally is not visible except
Dental radiograph
Sectioned tooth
 Develops from embryonic dental papilla ( mesoderm)
 Pulp is soft connective tissue containing a rich supply of
blood vessels and nerves
Function of the dental Pulp :
 Formative : dentin – producing cells (odontoblasts) produce
dentin through the life of the tooth ( called secondary dentin)
 Sensory : nerve endings permit sense ( heat , cold , sweet ,
decay , trauma , infection , drilling ) but does not distinguish
the cause of pain
 Nutritive : transport nutrients from the blood stream to cells
of the pulp that reach the osteoblasts in the dentin
 Defensive or protective : responds to injury or decay by
forming reparative dentin by odontoblasts ( replaced by
undifferentiated mesenchymal cells )
Anatomic versus clinical crown and root :
Anatomic crown and root :
 Anatomic crown : part of the tooth ( in the mouth or hand
held) normally covered by enamel surface
 Anatomic root : part of the tooth covered by a cementum
surface
 A cervical line ( cementoenamel junction ) separates the
Anatomic crown from the Anatomic root
Clinical crown and root :
 Clinical crown : the amount of tooth visible in the oral cavity
 Clinical root : amount of tooth not visible since it’s beneath
the gingiva
Clinical crown the same as the anatomical crown under these
situations :
Healthy gingiva or gingival line follows the curvature of the cervical
line ( on the same level)
But not always on the same level due to
 Eruption process early in life ( clinical crown shorter than
anatomic crown and clinical root longer than anatomic root)
 Or gingival recession later in life ( clinical crown longer than
anatomic crown and clinical root shorter than anatomic root)
Surfaces of anterior and posterior teeth (fig 3-3)
Named according to their alignment within the dental arch
 Facial surface : surface of the tooth toward the face ; outer
surfaces of the tooth in the mouth resting against or next to
the cheeks and lips
 For both anterior and posterior teeth
 Another name for posterior teeth only : buccal (teeth next to
the cheeks premolars and molars)
 Another name for anterior teeth only is : labial ( teeth next to
lips : incisors and canines)
Inner surfaces ( toward the tongue ) of the maxillary and
mandibular teeth :
Lingual surfaces : is the surface of the maxillary or mandibular
tooth nearest to the tongue
 In the maxillary arch also we call them palatal surface due
to proximity with the palate ( e.g 1st maxillary premolar)
Occlusal and Incisal surfaces :
 Occlusal surfaces : the chewing surface of the posterior
tooth ( premolars and molars)
 Incisal surfaces : the cutting edge , rigid or surface of the
anterior tooth ( incisors and canines )
Proximal surfaces of teeth
Proximal surface : sides of a tooth adjacent to the next tooth
 When facing the midline : mesial
 When away from the midline : distal
 All mesial surfaces touch or closest to (proximal) the distal
surface of the adjacent teeth except :
 The tow central incisors ( mesial surfaces face each
other)
 The 3rd molars in distal surface is not proximal to another
tooth
Proximal surface not self – cleansing
Facial , lingual . occlusal surfaces are self cleansing by
the action of cheeks lips and tongue
Division of the crown and root of a tooth (fig3-4)
Viewing a tooth from facial , lingual , mesial and distal
surfaces horizontal lines divide the tooth crown in to thirds
( from down (cervical line ) to up (occlusal surface) )
 Cervical
 Middle
 Occlusal
Horizontal lines divide the tooth roots also to ( from the
root top to the apex – up to down ) :
 Cervical
 Middle
 Apical
Viewing a tooth from the facial or lingual surface vertical
lines can divide the root or crown into :
 Mesial
 Middle
 Distal
Viewing a tooth from the proximal ( mesial or distal)
surface vertical lines can divide the root or crown into :
 Facial
 Middle
 Lingual thirds
TOOTH SURFACE JUNCTION OR DIMENSIONS
External line angle : the junction (line) where 2 surfaces
meet
 The 2 surfaces are combined by changing the (al)
ending in the first surface to an (o)
 Examples (fig 3-5)
 External-line angle of a molar crown :
 Mesio-ooclusal, mesiolingual,mesifacial,distoocclusal,distolingual ,distofacial,bucco-occlusal..etc
Point angles: the junction of three tooth surfaces at a point
Example
Mesiobucco-occlusal point angle
Dimensions of a tooth :
Combined terms can be used to denote direction over which the
dimension was taken
Examples :
 For an incisor crown the length from the incisal edge to the
cervical line could be called : incisocervical dimension or
dimension incisocervically (fig3-5)
 Other similar terms used to describe a crown dimension
include :
 Faciolingual , buccolingual , mesiodistal , cervicooclusal
 Root dimensions could be described as cervicoapical
ROOT CROWN RATIO ( see table 3-2) important
 The root length : from the cerviacal line to the tip of the root
(apex)
 The crown length : from the cervical line to the tip of the
longest cusp or ( higher part of the incisal edge)
ROOT CROWN RATIO = Root length / crown length
 If the ratio is small then the root is not much longer than
the crown
 Example
 Maxillary central incisor
Root length = 13 - crown length = 11.2
ROOT CROWN RATIO = 13/11.2 = 1.16
( small or closer to one)
This indicated tow things :
 the root is not much longer than the crown
 It’s clinically significant for attaching and supporting false
teeth because the additional attached teeth would apply
even more forces on a tooth that already has a short root
compared to it’s crown length ( not good for attachment of
teeth)
 if the ratio is large then the root is longer than the crown
Example
 Maxillary canine
Root length = 16.5 – crown length = 10.6
ROOT CROWN RATIO = 16.5/10.6 = 1.56
(large root crown ratio)
This indicates 2 things :
 Root longer than the crown
 It’s clinically significant for attaching and supporting false
teeth because the additional attached teeth would apply
even less forces on a tooth that already has a long root
compared to it’s crown length ( good for attachment)
MORPHOLOGY OF AN ANATOMIC CROWN
Teeth are made up of many bumps, ridges, and grooves
Canine (fig 3-8) and premolar (fig 3-9)
BULGES (ROUNDED) AND RIDGES ( LINEAR)
CUSP : (with a cusp tip) is a pointed peak or part located on the
 Occlusal surfaces of molars and premolars
 Incisal edges of canines
Each cusp is named according to it’s location on the tooth
Examples (fig 3-6)
 On a 2 cusp premolar the tow cusps are named buccal and
lingual
 On a four cusped molar the 4 cusps are named
mesiobuccal , distobuccal , mesioligual , distoligual
Each cusp tip
 Has Four cusp ridges (linear prominence) of enamel
converging toward it
 These ridges form the shape of a four – sided somewhat
rounded pyramid (fig3-7)
 On this cusp three of the ridges are named after the
circumferential tooth surface they extend toward :
1. the facial ( buccal or labial) ridge actually extends onto
the facial surface
2. the mesial cusp ridge extends from the cusp tip toward
the mesial surface
3. distal cusp ridge extends from the cusp tip toward the
distal surface
 The forth ridge from the cusp tip to the faciolingual
center of the tooth is called triangular ridge
 The mesial and distal cusp are also known as cusp slopes
or cusp arms
 They are inclined surfaces or slopes that converge at
the cusp tip from an angle when viewed from the facial
or lingual aspect ( fig3-9) seen on the facial view of a
canine and on the lingual cusp of premolar
 This cusp angle ( how sharp or how blunt) is an
important trait for cretin classes or types of teeth
MARGINAL RIDGES
 On incisor and canine teeth ( fig 3-8B) marginal ridges are
located on the mesial and distal border of the lingual
surfaces and converge toward the cingulum
 On posterior teeth they are located on the mesial and
distal borders of the occlusal surface ( fig 3-9A)
TRIANGULA RIDGES
 They are located on each major cusp of posterior teeth
 each triangular ridge extends from the cusp tip generally
toward the middle of the occlusal surface faciolingually
( fig 3-9A)
 each cusp on all posterior teeth has one triangular ridge
except the mesiolingual cusp on the maxillary molars
which has tow triangular ridges ( fig 3-10)
 when one triangular ridge from a facial cusp tip joins with a
triangular ridge from a lingual cusp tip the tow form a longer
ridge called either
 transverse ridge ( all posterior teeth)
 or oblique ridge ( only maxillary molars)
Transverse ridge : Crosses the occlusal surface of posterior teeth
in a more or less buccolingual direction
Example :
 Running between the buccal and lingual cusp on a premolar
( fig 3-9a)
 Between mesiolingual and mesiobuccal cusps on a molar (
fig 3-10)
Oblique ridge : found onley on maxillary molars
 It crosses the occlusal surface obliquely (diagonally)
 made up of the triangular ridges of the mesiolingual and
distobuccal cusps ( fig 3-10 maxillary 1st molar)
perhaps the sublet ridge coming off of the cusp tip id the
facial ( labial or buckle) ridge
 The buccal (cusp) ridge : is a subtle ridge running cervico –
occlusally in approximately the center of the buccal surfaces
of premolars
 more pronounced on the first premolar than on the second
premolar ( fig 3 – 9A)
The labial ridge : similar in appearance on canines it runs
cervicoincisally and is most prominent in the center of the maxillary
canines
The cingulum : the enlargement or bulge on the cervical third of
the lingual surface of the crown on anterior teeth ( incisors and
canines)
The cervical ridge : is a sublet ridge running mesiodistally in the
cerviacal one-third of the buccal surface of the crown
 Fond in facial surface of permanent molars and all primary
teeth ( fig 7-23)
Mamelons : three small tubercles or scallops each formed from :
 One of three facial developmental lobs on the incisal edge of
newly erupted incisors (fig 3-8B)
 Not evident on adult dentition since they are worn off after
tooth comes into functional contacts with it’s apposing tooth
 When remains in an adult , it’s because these teeth do not
contact opposing teeth in function
Perikymata : are the numerous ,minute ,horizontal ridges on the
enamel of newly erupted permanent teeth (fig3-13 and 3-14)
 They form of overlapping the layers of enamel laid down
during tooth formation
 These lines are closer together on the cervical part of the
crown than they are nearer the incisal edge
 They are easily seen on the labial surfaces of an anterior
teeth because of their accessible location
 More prominent on the teeth of young people than older
ones because they wear away from ongoing abrasion due to
eating and even tooth brushing with abrasive tooth pastes
DEPRESSIONS AND GRROVES
Sulcus : broad depression or vally on the occlusal surfaces of
posterior teeth
 The inclines of which are formed by triangular ridges that
often converge at the depth of the sculls in a developmental
groove
 Grooves and their sulci are important escape ways for
opposing upper and lower cusps and food morsels when the
mandible moves from side to side ( lateral movement) and
protrude forward (protrusive movement )
 Partially chewed food squirts out toward the tongue and
cheeks
Developmental grooves : sharply defined narrow linear
depression
 Short or long
 Formed during tooth development
 Usually separating the lopes or major portions of a tooth
Major grooves are named according to their location
Examples
(fig3-15) premolar
 central groove is located on the buccolingual center of the
tooth and runs mesiodustally
 at each end of the central groove both mesially and distally
fossa developmental grooves ( triangular fossa grooves)
may be found splitting off toward the corner of the tooth
 these grooves can be named for the corner of the tooth
toward which they aim
Example
The mesiobuccal fossa developmental groove ( sometimes
just called mesiobucaal groove)
 on many molars a buccal groove runs from the central
groove onto the buccal surface
 and a lingual groove extends from the central groove
onto the lingual surface (fig13-6)
 Other grooves that r not developmental grooves are called
supplemental grooves
 These small irregularly placed grooves on the occlusal
surface do not accrue at the junction of lopes or major
portions of the tooth
 They are named for the surface or corner of the tooth where
they are located ( e.g , mesiolingual supplemental groove )
(fig 3-15)
FISSURE: is a very narrow cleft or crvice at the depth of any
groove
 caused by the incomplete fusion of enamel during tooth
development ( fig 12-1)
 decay ( dental caries) often begins in a deep fissure
FOSSA: is a small hollow or depression
 found between the marginal ridges on the lingual
surfaces of the anterior teeth ( particulary maxillary
incisors)
 and on the occlusal surfaces of all posterior teeth
 pits : often occur at the depth of a fossa where tow or more
grooves joins
examples:
Within the mesial fossa on the premolar there is a mesial pit at
the junction of the central groove with the mesiobuccal and
mesiolingual fossa grooves 9fig 3-17A)
 Pits are enamel defects where dental decay may begin
( fig3-18) foosa and pits
EXTERNAL MORPHOLOGY OF THE ANATOMIC ROOT
( FIG3-17)
 anatomic root : is the part of the root that has cementum
surface
apex of the root is the tip of the peak or peak at the end of the
root ( often with visible openings called apical foraminae)
 apical foraminae where the nerves and blood supply enter
into the tooth pulp
cervix : or neck of the tooth is slightly constricted region of
union of the crown and root
Root trunk (apply to multirooted teeth)also call trunk base is
the part of the root of a multirooted molar or tow –rooted
premolar next to the cementoenamel junction that has not yet
split
Furcation : is the place on the multirooted teeth where the root
trunk divides into separate roots
 called bifurcation on tow- rooted tooth
 called trifurcation on three- rooted tooth
Furcal region (intra cellular space) : is the region or space
between tow or more roots
 it’s apical to the place where the root divides from the root
trunk
Relative size :
see table 3-2
TEETH DENTAL ARCHES
Viewing from occlusal aspect :
 Each dental arch is somewhat U shaped
 the incisal edges and the buccal cusps follow a curved
line around the outer edge of the dental arch
 the lingual cusp tips of the posterior teeth follow a cureved
line nearly parallel to the buccal cusp tips
 between the buccal and lingual cusps is the sulcular
groove ( which runs anteroposteriorly the length of the
posterior teeth )
Viewing from buccal aspect :
Anterioposterior curve ( curve of spee) is evident where the
cusp tips of posterior follow a gradual curve anteroposteriorly (fig320)
 the curve in the maxillary arch of teeth is convex
 while that in the mandibular arch of teeth that fit together
against the maxillary teeth is concave
Mediolateral curve ( curve of Wilson) is a side to side
curve(fig 10-7c p.304)
 when viewed from the anterior aspect with the mouth slightly
open you can see the lingual cusps of the posterior teeth are
aligned at a more inferior level than the buccal cusps on both
sides and in both arches
 when the buccal and lingual cusps of the molars or
premolars on either side of the arch are connected forming
one line from the left side to the right side , this curve is
evident .
 the mediolateral curve of the maxillary arch is convex
 where is that of the mandibular arch is concave
ROOT AXIS LINE : is an imaginary line through the center of the
tooth root
 when viewing on the facial or lingual surfaces as a line that
divides the tooth at the cervix into mesial and distal haves
(fig3-8A)
 when viewing the mesial or distal surfaces it can divides
the tooth at the cervix into facial and lingual halves (fig38B)
 it’s an important reference line for the description of location
and tooth land marks
 example : the incisal cusp ridge of many mandibular incisors
is more likely to be lingual to the root axis line ,whereas for
many maxillary incisors it’s more likely to be labial to the root
axis line
HIGHT OF CONTOUR (CREST OF CURVATURES)
The shape and height of the greatest curvature or convex bulge on
tooth surfaces helps determines the direction of food particles as
they are pushed cervically over the tooth surface during
mastication
 when we are chewing food these natural tooth convexities
divert food away from the collar tissue (gingiva)
 surrounding the neck of the tooth and toward the buccal
vestibule and toward the palate or tongue thus preventing
trauma to the gingival
 if teeth were flat in their middle and cervical thirds a great
deal of food would lodge and remain near the gingival margin
and sulcus until removed by by a tooth pick or tooth brush or
by dental floss
HIGHT OF CONTOUR (CREST OF CURVATURES) : is the
highest point of a curve of greatest convexity or bulge farthest from
the root axis line (fig3-17)
 The height of contour on the facial and lingual surfaces of the
crown is where this greatest bulge would be touched by a
tangent line drawn parallel to the root axis line(fig3-17)
 the location of the height of the contour on the facial and
lingual surfaces of crowns of teeth can be best seen from the
mesial or distal views and is usually located on either the
cervical third or middle third (never the occlusal or incisal
third)
 the location of the height of the contour on the facial surface
of all crowns is located on the cervical third
 the location of the lingual height contour differs depending on
whether the tooth is anterior or posterior :
 the lingual height of contour on anterior teeth is on the
cingulum which is in the cervical third
 the lingual height of contour on posterior teeth is more likely
to be located in the middle third
 see table 3-3
CONTACT AREA (PROXIMAL HEIGHTS OF CONTOURS)
when the teeth are in normal alignment within the arch the location
of the mesial and distal heights of contour(when viewed directly
from the facial or lingual side) is essentially the same location as
contact areas (facial view fig3-19 ,lingual view fig3-17)
contact area : greatest heights of contour on the proximal surface
of tooth crowns
 where tooth touches an adjacent tooth
 floss must pass through contact areas to clean proximal
surfaces which are other wise inaccessible to tooth brush
 in young person contact areas on teeth start off on
approximating teeth as contact points
 then as the teeth rub together in function theses points
become somewhat flattened and truly contact areas
 so we would expect that contact areas on teeth of older
people are larger and some what flattened
contact areas viewed from the facial are :
 located in the incisal or occlusal third
 in the middle third
 at the junction of the incisal and middle ( or occlusal and
middle) thirds
Contact point are not normally cervical to the middle of the tooth
crown and there for never located in cervical third ( fig3-19)
Functions:
1. the combined anchorage of all teeth within each arch making
positive contact with each other , stabilize the position of
teeth within the dental arch
2. contact helps prevents food impaction which contribute to
decay and gum and bon disease (periodontal disease)
3. contact protects the interdental papillae of the gingival by
shunting food toward the buccal and lingual areas
See table 3-3
Diastema : is the space between tow adjacent teeth that do not
contact each other ( fig3-21)
EMPRASURE SPACES
when adjacent teeth contact , the continuous spaces which
surrounds each contact area can be divided into 4 separate
triangular embrasure spaces (fig 3-19)
 these spaces are narrowest closest to the contact area
where the teeth in tight contact
1. widen facially to form the buccal or labial embrasure
2. widen lingualy to form the lingual embrasure
3. widen occlusally ( or incisally ) to form the occlusal or
incisal embrasure
4. the fourth space cervical to the contact area and between
tow adjacent teeth , is properly called intraproxima
space
Intraproximal space
 when viewed from the facial or lingual ; is a triangular
embrasure space between adjacent teeth located cervical
to their contact area
 the sides of the triangle are formed by the proximal
surfaces of adjacent teeth with the apex of the triangle at
the contact between tow teeth
 this space is occupied in peridontally healthy persons by
the interdental papillae ( fig 3-21 and fig 3-22)
 sometimes this interproximal space is referred to as the
cervical or gingival embrasure
Lingual embrasure
 ordinarily larger than the facial embrasure :
1. most teeth are narrower on the lingual side than on the
facial side
2. because their contact points are located facial to the
faciolingual midline of the crown
 these contact area location and buccal and lingual
embrasure are seen when dental arch is examined from the
occlusal view (fig3-19)
Occlusal or incisal embrasure : is the area between the marginal
ridges on tow adjacent teeth and occlusal to their contact area
 this is where we place the dental floss before passing it
through the contact area to clean tooth surfaces in the
interproximal space
 usually shallow from the occlusal surface or incisal edge to
the contact area
 is narrow faciolingually on the anterior teeth but broad on the
posterior teeth
Importance
 Embrasures surrounding good proximal contact areas serve
as spill ways to direct food away from the gingival
 when the occlusal embrasure is incorrectly shaped in a
dental restoration (amalgam,composite,gold) fibrous food will
readily lodge in the interproximal space and can be remove
only with a dental floss
 this food impaction is not just annoyance but it can contribute
to the formation of the dental decay and periodontal disease
( bone disease)
Ideal occlusion: inter (between) arch relation ship of teeth
Occlusion: is contacting of occlusal and incisal surfaces of
opposing maxillary and mandibular teeth
Ideal occlusion (class 1) : on the base of relation ship between
the maxillary and mandibular dental arches :
 when closed together the teeth are in their maximal
intercuspal position ( best fitting together ) of the teeth (fig
3-20,3-21,3-21)
 see page 103 ( important)
Tooth development from loops
 Tooth crowns are said to be developed from lobes or
primary growth center
 all normal teeth shows evidence of having developed from
three or more lobes
 the facial portion of incisors ,canines and premolars
forms from three lobes
 the cingulum area and lingual cusp each form from one
lobe
So incisors develop from four lobes :
 three facial lobes forming three incisally located mamelons
 one lingual lobe forming the cingulum area
Canines and most premolars also develop from four lobes :
 three facial lobes forming the facial portion
 one lingual lobe forming the cingulum area on the canine and
on the lingual cusp
An exception is the three –cusp type premolar have ( one
buccal and tow lingual so it have five lobes :
 three forming the facial cusp
 tow ( one each) forming lingual cusps
The three lobes of the facial surface of an anterior tooth and
premolars are usually evidence by the three very subtle
vertical ridges separated by tow depressions
As a general rule each molar cusp forms from one lobe
example
 mandibular first molar has five cusps ( three buccal and 2
lingual) and develops from 5 lobes
 onley some maxillary third molars have as few as three lobes
forming three cusps .
Tow types of tooth anomalies
 Peg shaped maxillary lateral incisors and
 some extra teeth also called supernumerarey teeth form from
less than three lobes
Please see the tables and the figures it’s important  good
luck