Normal Occlusion Characteristics

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Normal Occlusion & it’s Characteristics

Normal occlusionNormal occlusion
• The definition of the term occlusion inThe definition of the term occlusion in
many dictionaries states that it is themany dictionaries states that it is the
act of closure or being closedact of closure or being closed..

Normal occlusionNormal occlusion
““ Normal” means absence of any diseaseNormal” means absence of any disease
with functional adaptability and capabilitywith functional adaptability and capability
of the masticatory system to compensateof the masticatory system to compensate
for any deviation within the range offor any deviation within the range of
tolerance.tolerance.

Definitions:Definitions:
Angle:Angle:
AngleAngle defines occlusion as the normaldefines occlusion as the normal
relation of the occlusal inclined planes ofrelation of the occlusal inclined planes of
the teeth when the jaws are closed.the teeth when the jaws are closed.
Wheeler’s:Wheeler’s:
It may be defined as the contact relationshipIt may be defined as the contact relationship
of the teeth in function or parafunction.of the teeth in function or parafunction.

When the jaws are closed and the heads ofWhen the jaws are closed and the heads of
the condyles are in the resting position inthe condyles are in the resting position in
the glenoid fossa, the cusps , fossae andthe glenoid fossa, the cusps , fossae and
incisal edges of individual teeth of theincisal edges of individual teeth of the
upper and lower arches comes intoupper and lower arches comes into
contact with one another, the sum of thesecontact with one another, the sum of these
relations make up the occlusion of therelations make up the occlusion of the
dentition.dentition.

AA normal occlusionnormal occlusion considersconsiders
• occlusal contactsocclusal contacts
• alignment of teethalignment of teeth
• overbite , overjetoverbite , overjet
• arrangement and relationship of teeth withinarrangement and relationship of teeth within
and between the archesand between the arches
• relationship of the teeth to osseous structuresrelationship of the teeth to osseous structures
• relations of the neuromuscular mechanism torelations of the neuromuscular mechanism to
the occlusion.the occlusion.

Occlusion is a complex phenomenonOcclusion is a complex phenomenon
involvinginvolving
1.1. the teeththe teeth
2.2. periodontal ligamentsperiodontal ligaments
3.3. the jawsthe jaws
4.4. the temporomandibular jointthe temporomandibular joint
5.5. the muscles of masticationthe muscles of mastication
6.6. the nervous systemthe nervous system

Ideal Occlusion (Text Book Occlusion)Ideal Occlusion (Text Book Occlusion)
It is a pre-conceived theoretical concept ofIt is a pre-conceived theoretical concept of
occlusal structure and functionalocclusal structure and functional
relationship that include idealizedrelationship that include idealized
principles of characteristics that anprinciples of characteristics that an
occlusion should have.occlusion should have.
This concept refers to both to an aestheticThis concept refers to both to an aesthetic
and a physiologic ideal. Important aspectand a physiologic ideal. Important aspect
of ideal occlusion includes functionalof ideal occlusion includes functional
harmony and stability of masticatoryharmony and stability of masticatory
system and neuromuscular harmony in thesystem and neuromuscular harmony in the
masticatory system.masticatory system.

It refers to an occlusion that deviates in oneIt refers to an occlusion that deviates in one
or more ways from ideal, yet it is wellor more ways from ideal, yet it is well
adapted to that particular environment, isadapted to that particular environment, is
esthetic and shows no pathologicesthetic and shows no pathologic
manifestations or dysfunction.manifestations or dysfunction.
Physiologic occlusionPhysiologic occlusion

Balanced occlusion is said to exist whenBalanced occlusion is said to exist when
there exist a simultaneous contact ofthere exist a simultaneous contact of
maxillary and mandibular teeth on rightmaxillary and mandibular teeth on right
and left (working and balancing side), inand left (working and balancing side), in
the anterior and posterior occlusal areasthe anterior and posterior occlusal areas
when the jaws are either in centric orwhen the jaws are either in centric or
eccentric occlusion.eccentric occlusion.
Balanced occlusionBalanced occlusion

It is defined as an arrangement of teethIt is defined as an arrangement of teeth
which will provide the highest efficiencywhich will provide the highest efficiency
during all the excessive movements of theduring all the excessive movements of the
mandible which are necessary duringmandible which are necessary during
function.function.
Functional occlusionFunctional occlusion

An occlusion that has been modified byAn occlusion that has been modified by
appropriate therapeutic modalities in orderappropriate therapeutic modalities in order
to change a non physiological occlusion toto change a non physiological occlusion to
one that is at least physiologic, if not ideal.one that is at least physiologic, if not ideal.
Therapeutic occlusion:-Therapeutic occlusion:-

Traumatic occlusion is an abnormal occlusalTraumatic occlusion is an abnormal occlusal
stress which is capable of producing orstress which is capable of producing or
has produced an injury to thehas produced an injury to the
periodontiumperiodontium
7.Traumatic occlusion7.Traumatic occlusion

• Protrusive movement of mandible:-Protrusive movement of mandible:-
• In mandibular movements like speech,In mandibular movements like speech,
swallowing, protrusion both the sides of theswallowing, protrusion both the sides of the
jaw moves equally about an horizontal axis.jaw moves equally about an horizontal axis.

• Horizontal axis will move along with theHorizontal axis will move along with the
condyles as they move back and forth alongcondyles as they move back and forth along
the eminence.the eminence.
• The vertical space between maxillary andThe vertical space between maxillary and
mandibular teeth on both sides will bemandibular teeth on both sides will be
equal.equal.

• Lateral movement of mandible:-Lateral movement of mandible:-

• During the lateral movement mandible doesDuring the lateral movement mandible does
not move symmetrically.not move symmetrically.
• One of the condyle termed working condyleOne of the condyle termed working condyle
is relatively stationary and mandibleis relatively stationary and mandible
appears to rotate about a vertical axisappears to rotate about a vertical axis
through the stationary working condyle.through the stationary working condyle.
• Other condyle (non working) moves forwardOther condyle (non working) moves forward
and downward in addition to it, this condyleand downward in addition to it, this condyle
will have medial movement.will have medial movement.

Centric RelationCentric Relation
• Centric relationCentric relation is theis the
relation of therelation of the
mandible to themandible to the
maxilla when themaxilla when the
mandibular condylesmandibular condyles
are in most superiorare in most superior
and retruded positionand retruded position
in their glenoid fossain their glenoid fossa
with the articular discwith the articular disc
properly interposed.properly interposed.
• Also called asAlso called as
ligamentous positionligamentous position
oror terminal hingeterminal hingewww.indiandentalacademy.comwww.indiandentalacademy.com

Centric OcclusionCentric Occlusion
• Centric occlusionCentric occlusion isis
that position ofthat position of
mandibular condylemandibular condyle
when jaws are closedwhen jaws are closed
and the teeth are inand the teeth are in
maximummaximum
intercuspation.intercuspation.
• It is also called asIt is also called as
Inter-cuspalInter-cuspal positionposition
oror convenienceconvenience
occlusion.occlusion. www.indiandentalacademy.comwww.indiandentalacademy.com

• Centric relation and centric occlusion shouldCentric relation and centric occlusion should
coincide in order to have perfect harmonycoincide in order to have perfect harmony
between the teeth, the temporo mandibular jointbetween the teeth, the temporo mandibular joint
and neuromuscular system.and neuromuscular system.
• Maximum intercuspation can also occur withoutMaximum intercuspation can also occur without
the condyles being in centric relation. This isthe condyles being in centric relation. This is
calledcalled habitual occlusionhabitual occlusion oror acquired occlusionacquired occlusion..
In such cases, the movement from theIn such cases, the movement from the
premature contact in centric relation to centricpremature contact in centric relation to centric
occlusion is calledocclusion is called a slide in centric.a slide in centric.

Physiologic Rest PositionPhysiologic Rest Position
• In this position the upper and lower jaws are notIn this position the upper and lower jaws are not
in contact and the space between the upper andin contact and the space between the upper and
lower teeth is called as thelower teeth is called as the freeway space .freeway space .
• This position is obtained when all the jawThis position is obtained when all the jaw
muscles are at rest.muscles are at rest.
• This measures on average 2-5 mm at the incisalThis measures on average 2-5 mm at the incisal
area.area.
• The lips are generally closed during thisThe lips are generally closed during this
position. It is constant throughout life and is notposition. It is constant throughout life and is not
dependent on the presence or absence of teeth.dependent on the presence or absence of teeth.
• All functional movements begin and end withAll functional movements begin and end with
rest position.rest position.

Centric ContactCentric Contact
They are the areas ofThey are the areas of
the teeth thatthe teeth that
contact the opposingcontact the opposing
teeth.teeth.
There are two types ofThere are two types of
centric contacts:centric contacts:
1.1. Posterior centricPosterior centric
contacts:-contacts:-
2.2. Anterior centricAnterior centric
contactcontact

Posterior centric contactsPosterior centric contacts
• Facial range of posterior centric contactFacial range of posterior centric contact
involve mandibular facial cusps tips contactinginvolve mandibular facial cusps tips contacting
central fossae and mesial marginal ridges ofcentral fossae and mesial marginal ridges of
the opposing maxillary teeth.the opposing maxillary teeth.
• Lingual range of posterior centric contactLingual range of posterior centric contact
involves the maxillary lingual cusps tipsinvolves the maxillary lingual cusps tips
contacting the central fossae and distalcontacting the central fossae and distal
marginal ridges of the opposing mandibularmarginal ridges of the opposing mandibular
teeth.teeth.

Anterior teeth have only one range of centricAnterior teeth have only one range of centric
contacts and are in line with the facial range ofcontacts and are in line with the facial range of
posterior centric contacts.posterior centric contacts.
Anterior centric contacts:-Anterior centric contacts:-

Centric contacts often occurs on inclines ofCentric contacts often occurs on inclines of
posterior teeth. These contacts thatposterior teeth. These contacts that
occurs on one incline are calledoccurs on one incline are called podedpoded
centriccentric contact.contact. If contact occurs betweenIf contact occurs between
two inclines the contact is termed bipodedtwo inclines the contact is termed bipoded
contact. If contact occurs on 3 inclines it iscontact. If contact occurs on 3 inclines it is
called tripoded contacts and If contactcalled tripoded contacts and If contact
occurs on 4 inclines it is calledoccurs on 4 inclines it is called
quadrapoded contacts.quadrapoded contacts.

Eccentric occlusionEccentric occlusion
This refers to contact of teeth that occursThis refers to contact of teeth that occurs
during movements of the mandible.during movements of the mandible.
It is of two types:It is of two types:
a)a) Functional occlusion.Functional occlusion.
b)b) Non functional occlusion.Non functional occlusion.

(working side occlusion )(working side occlusion )
It refers to tooth contact that occur in theIt refers to tooth contact that occur in the
segment of the arch towards which thesegment of the arch towards which the
mandible moves.mandible moves.
Lateral functionalLateral functional
occlusionocclusion
Protrusive functionalProtrusive functional
occlusionocclusion

Lateral functional occlusionLateral functional occlusion
• It includes tooth contacts that occur onIt includes tooth contacts that occur on
canine and posterior teeth on the sidecanine and posterior teeth on the side
towards which the mandible moves.towards which the mandible moves.
• It is also of two types:It is also of two types:
1.1. Canine guided occlusionCanine guided occlusion
2.2. Grouped lateral occlusionGrouped lateral occlusion

Canine guided occlusionCanine guided occlusion
• During the lateral mandibular movements,During the lateral mandibular movements,
the opposing upper and lower canines ofthe opposing upper and lower canines of
working side contact thereby causingworking side contact thereby causing
disocclusion of all posterior teeth on thedisocclusion of all posterior teeth on the
working and balancing sides.working and balancing sides.
• Canine guided occlusion is usually seen inCanine guided occlusion is usually seen in
young individual with unworn dentition.young individual with unworn dentition.

• Prevents the breakdown of periodontalPrevents the breakdown of periodontal
fibers of posteriors and incisors.fibers of posteriors and incisors.
• Cannot be possible in periodontallyCannot be possible in periodontally
compromised canines or missing canines.compromised canines or missing canines.

Canine guidance in right and left
laterotrusion

Grouped lateral occlusionGrouped lateral occlusion
In addition to canineIn addition to canine
guidance, certainguidance, certain
other posterior teethother posterior teeth
on the working sideon the working side
also contact duringalso contact during
lateral movement oflateral movement of
mandible, such typemandible, such type
of contact duringof contact during
lateral movement islateral movement is
called grouped lateralcalled grouped lateral
occlusion.occlusion. www.indiandentalacademy.comwww.indiandentalacademy.com

• In this type of occlusion working sideIn this type of occlusion working side
contacts extends posteriorly involvingcontacts extends posteriorly involving
premolars, and mesiobuccal cusp of firstpremolars, and mesiobuccal cusp of first
molar.molar.
• Can be achieved when canine guidance isCan be achieved when canine guidance is
not possible.not possible.
• Pressure difference between molars andPressure difference between molars and
anteriors is not taken into consideration.anteriors is not taken into consideration.

Protrusive functional occlusionProtrusive functional occlusion
Includes eccentricIncludes eccentric
contacts that occurscontacts that occurs
when the mandiblewhen the mandible
moves forward.moves forward.
Ideally six mandibularIdeally six mandibular
anterior teeth contactanterior teeth contact
along the lingualalong the lingual
inclines of theinclines of the
maxillary anteriormaxillary anterior
teeth while theteeth while the
posterior disocclude.posterior disocclude.

Non functional occlusionNon functional occlusion
• They are tooth contact that occur in theThey are tooth contact that occur in the
segment away from which the mandiblesegment away from which the mandible
moves.moves.

DisocclusionDisocclusion
• It refers to separation of non functionalIt refers to separation of non functional
posterior teeth during eccentric motions ofposterior teeth during eccentric motions of
the jaw .the jaw .
• Disclusion of posterior teeth is broughtDisclusion of posterior teeth is brought
about byabout by condylar guidancecondylar guidance andand incisalincisal
guidance.guidance.

Anterior guidance/Incisal guidanceAnterior guidance/Incisal guidance
It refers to anterior tooth functions whichIt refers to anterior tooth functions which
separates the posterior teeth duringseparates the posterior teeth during
eccentric motions of the jaw. Duringeccentric motions of the jaw. During
protrusive and lateral movement of theprotrusive and lateral movement of the
mandible, the lower anterior teeth tracesmandible, the lower anterior teeth traces
downward from their area of centricdownward from their area of centric
contact towards the incisal edges ofcontact towards the incisal edges of
maxillary teeth while disoccluding the non-maxillary teeth while disoccluding the non-
functional posterior teeth.functional posterior teeth.

• Incisal guidance determined primarily byIncisal guidance determined primarily by
lingual surface of maxillary anteriors andlingual surface of maxillary anteriors and
controls the posterior disclusion duringcontrols the posterior disclusion during
protrusion.protrusion.
• In normal occlusal relationship protrusiveIn normal occlusal relationship protrusive
contacts occurs only on anterior teeth.contacts occurs only on anterior teeth.
(guiding inclines of anterior teeth)(guiding inclines of anterior teeth)

• Reasons:-Reasons:-
• Incisors are located far away from TMJIncisors are located far away from TMJ
creating less amount of stresses on them.creating less amount of stresses on them.
• Gliding type of movement is more adaptiveGliding type of movement is more adaptive
to the incisors due to their favorableto the incisors due to their favorable
anatomy.anatomy.

• Condylar guidanceCondylar guidance refers to the downwardrefers to the downward
movement of both the condyles along themovement of both the condyles along the
slopes of the articular eminence duringslopes of the articular eminence during
protrusive movements leading toprotrusive movements leading to
separation of the posteriors.separation of the posteriors.
• In case of lateral movements, theIn case of lateral movements, the
condyles on the non-functioning sidecondyles on the non-functioning side
translates forward along the eminencetranslates forward along the eminence
while the condyle on the functioning sidewhile the condyle on the functioning side
pivots in its fossa leading to disclusion ofpivots in its fossa leading to disclusion of
posterior teeth on the non-functional side.posterior teeth on the non-functional side.

• Condylar guidance has its greatestCondylar guidance has its greatest
influence on discluding the most distalinfluence on discluding the most distal
posterior teeth while incisal guidanceposterior teeth while incisal guidance
provides discluding effect on the moreprovides discluding effect on the more
mesial teeth.mesial teeth.
• The condylar guidance is a fixed anatomicThe condylar guidance is a fixed anatomic
factor that can not be controlled by thefactor that can not be controlled by the
dentist while the incisal guidance can bedentist while the incisal guidance can be
controlled by modifying the form andcontrolled by modifying the form and
arrangement of the anterior teeth.arrangement of the anterior teeth.

Aspects of occlusionAspects of occlusion
OCCLUSION
STATIC DYNAMIC

• StaticStatic
• refers to the form, alignment andrefers to the form, alignment and
articulation of the teeth within andarticulation of the teeth within and
between the arches and the relationship ofbetween the arches and the relationship of
teeth to their supporting structure whenteeth to their supporting structure when
the jaws are stationary.the jaws are stationary.
• DynamicDynamic
• refers to the function of therefers to the function of the
stomatognathic system as a wholestomatognathic system as a whole
comprising teeth , supporting structures ,comprising teeth , supporting structures ,
TMJ , neuromuscular and nutritiveTMJ , neuromuscular and nutritive
systems.systems.

CUSPS
SUPPORTING CUSPS
OR
CENTRIC HOLDING CUSPS
OR
STAMP CUSPS
NON SUPPORTING CUSPS
OR
SHEARING CUSPS
OR
GUIDING CUSPS

Supporting cusps /Centric holding cups/stampSupporting cusps /Centric holding cups/stamp
cupscups
The buccal cusps of mandibular and palatalThe buccal cusps of mandibular and palatal
cups of maxillary posterior teeth are calledcups of maxillary posterior teeth are called
stamp cusps. They occlude into the centralstamp cusps. They occlude into the central
fossae and marginal ridges of opposing teeth.fossae and marginal ridges of opposing teeth.
these cusp are called ‘centric cusps’ or supportingthese cusp are called ‘centric cusps’ or supporting
cusps, because they act as vertical stop duringcusps, because they act as vertical stop during
jaw movementsjaw movements
• These cusp plays major role in mastication andThese cusp plays major role in mastication and
to maintain vertical dimension between maxillato maintain vertical dimension between maxilla
and mandible.and mandible.

Non-supporting cusps/ShearingNon-supporting cusps/Shearing
cusps or guiding cuspscusps or guiding cusps
The maxillary buccal and mandibular lingual cuspsThe maxillary buccal and mandibular lingual cusps
are called non-supporting, shearing or guidingare called non-supporting, shearing or guiding
cusps.cusps.
• Gives stability to mandible in fullGives stability to mandible in full
occlusion.occlusion.
• Guide the mandible during mastication byGuide the mandible during mastication by
neuromuscular feedbackneuromuscular feedback
• Shearing of food.Shearing of food.
• Minimizing tissue impingement.Minimizing tissue impingement.
• Maintain bolus of food on occlusal table forMaintain bolus of food on occlusal table for
masticationmastication www.indiandentalacademy.comwww.indiandentalacademy.com

Non centric cuspsNon centric cusps

• Overjet and overbite –Overjet and overbite –
• It is determined byIt is determined by
horizontal and verticalhorizontal and vertical
overlap of anterior teethoverlap of anterior teeth
• Ideal over jet andIdeal over jet and
overbite is 2 mmoverbite is 2 mm
• Important for disclusionImportant for disclusion
of posterior teeth duringof posterior teeth during
the forward movementthe forward movement
of mandible and thusof mandible and thus
reduce the periodontalreduce the periodontal
breakdown of posteriorbreakdown of posterior
teeth.teeth.

Arrangement of teeth inArrangement of teeth in
humanshumans
Human dentition exhibits two types of toothHuman dentition exhibits two types of tooth
arrangement when upper and lowerarrangement when upper and lower
teeth occlude with one another:teeth occlude with one another:
1.1. Cups-fossa occlusionCups-fossa occlusion
2.2. Cusp-embrasure occlusionCusp-embrasure occlusion

Cusp fossa occlusion/ toothCusp fossa occlusion/ tooth
to tooth arrangement:to tooth arrangement:
• In this type of occlusionIn this type of occlusion
the stamp cusp of onethe stamp cusp of one
tooth occludes in a singletooth occludes in a single
fossa of a singlefossa of a single
opponent. The upperopponent. The upper
stamp cusps fit into allstamp cusps fit into all
except the mesial fossaexcept the mesial fossa
of the lower teeth whileof the lower teeth while
lower stamp cusps fit intolower stamp cusps fit into
all the upper fossa exceptall the upper fossa except
the distal ones ofthe distal ones of
bicuspids.bicuspids.
• This kind of arrangementThis kind of arrangement
where contact occurswhere contact occurs
between single opposingbetween single opposing
teeth is called a cuspteeth is called a cusp
fossa occlusion or a toothfossa occlusion or a tooth
to tooth arrangement.to tooth arrangement.

Cusp-embrasure occlusionCusp-embrasure occlusion
or tooth to two teethor tooth to two teeth
occlusionocclusion
This type of occlusionThis type of occlusion
results in fitting of oneresults in fitting of one
stamp cusp into a fossastamp cusp into a fossa
and the fitting of anotherand the fitting of another
cusp of the same toothcusp of the same tooth
into the embrasure areainto the embrasure area
of two opposing teeth.of two opposing teeth.
In this type of arrangementIn this type of arrangement
each tooth occludes witheach tooth occludes with
two opposing teethtwo opposing teeth

Advantages of cusp-fossa arrangementAdvantages of cusp-fossa arrangement::
1.1. Forces are directed more towards theForces are directed more towards the
long axis of the teeth.long axis of the teeth.
2.2. The arrangement leads to greaterThe arrangement leads to greater
stability of the arch, decreasing thestability of the arch, decreasing the
tendency towards tooth movement.tendency towards tooth movement.
3.3. The chances of food impacting in theThe chances of food impacting in the
embrasures is lessembrasures is less

Development of occlusion inDevelopment of occlusion in
primary dentitionprimary dentition
• Primary dental arch is ovoid.Primary dental arch is ovoid.
• In early stages tongue plays an importantIn early stages tongue plays an important
role in the shaping of dental arches.role in the shaping of dental arches.
• With eruption of primary first molar the firstWith eruption of primary first molar the first
three dimensional occlusal relationshipsthree dimensional occlusal relationships
established.established.

The normal occlusion of theThe normal occlusion of the
primary teeth at the age ofprimary teeth at the age of
three years is as follows:three years is as follows:
1.1. Mesial surfaces of maxillaryMesial surfaces of maxillary
and mandibular centraland mandibular central
incisors are in line with eachincisors are in line with each
other at the median line.other at the median line.
2.2. The maxillary central incisorThe maxillary central incisor
occludes with the mandibularoccludes with the mandibular
central incisor and mesial thirdcentral incisor and mesial third
of the mandibular lateralof the mandibular lateral
incisor. The mandibularincisor. The mandibular
anterior teeth strike theanterior teeth strike the
maxillary anterior teethmaxillary anterior teeth
lingually above the level of thelingually above the level of the
incisal ridges.incisal ridges. www.indiandentalacademy.comwww.indiandentalacademy.com

3. The maxillary lateral incisor occludes with3. The maxillary lateral incisor occludes with
the distal two third of the mandibularthe distal two third of the mandibular
lateral incisors and that portion of thelateral incisors and that portion of the
mandibular canine which is mesial to themandibular canine which is mesial to the
point of its cusp.point of its cusp.
4. The maxillary canine occludes with that4. The maxillary canine occludes with that
portion of the mandibular canine distal toportion of the mandibular canine distal to
its cusp tip and the mesial third ofits cusp tip and the mesial third of
mandibular first molar.mandibular first molar.

5. The maxillary first molar occludes with the5. The maxillary first molar occludes with the
distal two third of the mandibular firstdistal two third of the mandibular first
molar and the mesial portion ofmolar and the mesial portion of
mandibular second molar which portion ismandibular second molar which portion is
represented by the mesial marginal ridgerepresented by the mesial marginal ridge
and the mesial triangular ridge.and the mesial triangular ridge.
6. The maxillary second molar occludes with6. The maxillary second molar occludes with
the remainder if the mandibular secondthe remainder if the mandibular second
molar, the distal surface of maxillary molarmolar, the distal surface of maxillary molar
projecting slightly over the distal portion ofprojecting slightly over the distal portion of
the mandibular second molar.the mandibular second molar.

• Mesiolingual cusp of maxillary molarMesiolingual cusp of maxillary molar
occludes in the central fossa of mandibularoccludes in the central fossa of mandibular
molars, incisors are vertical with minimalmolars, incisors are vertical with minimal
overbite and over jet. and flush terminaloverbite and over jet. and flush terminal
plane at the end of primary dentition.plane at the end of primary dentition.

Characteristics of occlusion inCharacteristics of occlusion in
primary dentition :-primary dentition :-
• Spaced anteriorsSpaced anteriors
• Primate spacesPrimate spaces
• Shallow overbite andShallow overbite and
over jetover jet
• Straight terminalStraight terminal
planeplane
• Class I molar andClass I molar and
canine relationshipcanine relationship
• Vertical inclination ofVertical inclination of
anterior teethanterior teeth
• Ovoid arch formOvoid arch formwww.indiandentalacademy.comwww.indiandentalacademy.com

OCCLUSAL CHANGES IN THEOCCLUSAL CHANGES IN THE
MIXED DENTITIONMIXED DENTITION
• FIRST TRANSITIONAL PERIODFIRST TRANSITIONAL PERIOD
Establishment of occlusionEstablishment of occlusion
The development of class I occlusion fromThe development of class I occlusion from
flush terminal plane.flush terminal plane.

Flush/Vertical Terminal planeFlush/Vertical Terminal plane
• when distal surfaces of upper and lowerwhen distal surfaces of upper and lower
deciduous second molars are in one plane.deciduous second molars are in one plane.
• the permanent 1st molar erupts initially into athe permanent 1st molar erupts initially into a
cusp to cusp or end on relationship which latercusp to cusp or end on relationship which later
transforms into a class I by moving the lowertransforms into a class I by moving the lower
molars 3 to 5 mm in relation to upper molarmolars 3 to 5 mm in relation to upper molar
-either by utilization physiologic spaces/leeway-either by utilization physiologic spaces/leeway
spaces.spaces.
-or by differential forward growth of mandible.-or by differential forward growth of mandible.
FLUSH TERMINAL
PLANE

MESIAL STEPMESIAL STEP
Distal surface of mandibular deciduous 2ndDistal surface of mandibular deciduous 2nd
molar is mesial to the distal surface ofmolar is mesial to the distal surface of
maxillary deciduous 2nd molar.maxillary deciduous 2nd molar.
MESIAL STEP TERMINAL
PLANE
In this relationship permanent molars erupt
directly into Angle’s class I occlusion

DISTAL STEPDISTAL STEP
distal surface of mandibular deciduous 2nd molardistal surface of mandibular deciduous 2nd molar
is more distal than the distal surface of max.is more distal than the distal surface of max.
deciduous second molardeciduous second molar
Erupting molars may be in Angle’s class IIErupting molars may be in Angle’s class II
DISTAL STEP TERMINAL
PLANE

Occlusion in PermanentOcclusion in Permanent
dentitiondentition
It can be discussed under following pointIt can be discussed under following point
1.1. Dental arch form.Dental arch form.
2.2. Compensating curvatures of dental arches.Compensating curvatures of dental arches.
3.3. Compensating curvatures of individual teeth .Compensating curvatures of individual teeth .
4.4. Angulations and inclination of teeth in relationAngulations and inclination of teeth in relation
to various planes.to various planes.
5.5. Functional form of teeth at their incisal orFunctional form of teeth at their incisal or
occlusal thirdocclusal third

6. Facial and lingual relations of each tooth6. Facial and lingual relations of each tooth
in one arch to its antagonist orin one arch to its antagonist or
antagonists in the opposing arch inantagonists in the opposing arch in
centric occlusion.centric occlusion.
7. Occlusal contacts and intercuspal7. Occlusal contacts and intercuspal
relations of all the teeth of one arch withrelations of all the teeth of one arch with
those in the opposing arch in centricthose in the opposing arch in centric
8. Occlusal contacts and intercuspal8. Occlusal contacts and intercuspal
relations of all the teeth of one arch withrelations of all the teeth of one arch with
those in the opposing arch in variousthose in the opposing arch in various
mandibular movements.mandibular movements.
9. Neuromuscular aspect of occlusion.9. Neuromuscular aspect of occlusion.www.indiandentalacademy.comwww.indiandentalacademy.com

Dental arch formDental arch form
1.1. From occlusal aspectFrom occlusal aspect
the dental arches arethe dental arches are
parabolic in shape.parabolic in shape.
The shape isThe shape is
determined bydetermined by
underlying basal bone.underlying basal bone.
2.2. With advancing ageWith advancing age
dental arch perimeterdental arch perimeter
decreases.decreases.
1.1. Maxillary arch >Maxillary arch >
Mandibular arch.Mandibular arch.

Compensating curvatures of dentalCompensating curvatures of dental
archesarches
• The anteroposterior & lateral curvatures in theThe anteroposterior & lateral curvatures in the
alignment of the occluding surfaces &incisalalignment of the occluding surfaces &incisal
edges of teethedges of teeth
Mandibular arch conforms to a curved planeMandibular arch conforms to a curved plane
which appears concave and maxillary archwhich appears concave and maxillary arch
appears convex.appears convex.
• It is of two type :-It is of two type :-
Anteroposterior curve :-Curve of SpeeAnteroposterior curve :-Curve of Spee
Lateral curve :- Curve of WilsonLateral curve :- Curve of Wilson
Curve of MonsonCurve of Monson

Curve of SpeeCurve of Spee
• First described by Von Spee in 1928

Curve of Spee:-Curve of Spee:-
It refers to theIt refers to the
anteriorposterioranteriorposterior
curvature of thecurvature of the
occlusal surfaceocclusal surface
beginning at the tipbeginning at the tip
of the lower cuspidof the lower cuspid
and following theand following the
cusps tip of thecusps tip of the
bicuspids andbicuspids and
molars continuingmolars continuing
as an arc throughas an arc through
the condyle.the condyle.

Normal value is 1.5mmNormal value is 1.5mm
If the curve is extended, it would form a circle ofIf the curve is extended, it would form a circle of
about 4” diameter.about 4” diameter.
Significance:-Significance:-
Deep curve of Spee result in deep bite.Deep curve of Spee result in deep bite.

The curve results fromThe curve results from
variations in axialvariations in axial
alignment of lower teeth.alignment of lower teeth.
The long axis of eachThe long axis of each
lower tooth is alignedlower tooth is aligned
nearly parallel to itsnearly parallel to its
individual arc of closureindividual arc of closure
around the condylar axis.around the condylar axis.
This requires a gradualThis requires a gradual
progressive increasedprogressive increased
mesial tilting of teethmesial tilting of teeth
towards molars whichtowards molars which
creates the curve ofcreates the curve of
Spee.Spee. www.indiandentalacademy.comwww.indiandentalacademy.com

– This is a curve thatThis is a curve that
contacts the buccalcontacts the buccal
and lingual cuspsand lingual cusps
tips of thetips of the
mandibular posteriormandibular posterior
teeth.teeth.
The curve of Wilson isThe curve of Wilson is
medio-lateral onmedio-lateral on
each side of theeach side of the
arch. It results fromarch. It results from
the inwardthe inward
inclination of lowerinclination of lower
posterior teeth.posterior teeth.
Curve of Wilson:-Curve of Wilson:-

• posterior teeth in maxillary arch have slightposterior teeth in maxillary arch have slight
buccal inclination and mandibular arch havebuccal inclination and mandibular arch have
lingual inclination.lingual inclination.

This curve helps inThis curve helps in
two ways:-two ways:-
A) Teeth are alignedA) Teeth are aligned
parallel to theparallel to the
direction of medialdirection of medial
pterygoid forpterygoid for
optimum resistanceoptimum resistance
to masticatoryto masticatory
forces.forces.
B) The elevatedB) The elevated
buccal cuspsbuccal cusps
prevent food fromprevent food from
going past thegoing past the
occlusal table.occlusal table.www.indiandentalacademy.comwww.indiandentalacademy.com

3. Curve of Monson:-3. Curve of Monson:-
• The curve of occlusion in which each cusp andThe curve of occlusion in which each cusp and
incisal edges touches to a segment of sphereincisal edges touches to a segment of sphere
• The diameter of sphere is 8’’ & it’s centre is inThe diameter of sphere is 8’’ & it’s centre is in
the regeion of glabellathe regeion of glabella
• This curve runs across palatal & buccal cuspsThis curve runs across palatal & buccal cusps
of the maxillary molarsof the maxillary molars

Compensating curvatures ofCompensating curvatures of
individual teethindividual teeth
Vertical section of the jaws with the teeth inVertical section of the jaws with the teeth in
centric occlusion demonstrates the fact thatcentric occlusion demonstrates the fact that
axes of the posterior teeth approach alignmentaxes of the posterior teeth approach alignment
with each other but these axes are notwith each other but these axes are not
perpendicular to the horizontal plane.perpendicular to the horizontal plane.
Any line which bisects crown and root of toothAny line which bisects crown and root of tooth
from any aspect exhibits some curvature. Thisfrom any aspect exhibits some curvature. This
was termedwas termed spherical congruencyspherical congruency byby MaxwellMaxwell..

Angulations and inclination of rootsAngulations and inclination of roots
of teeth in relation to variousof teeth in relation to various
planesplanes
• The mesiodistal and the faciolingual axialThe mesiodistal and the faciolingual axial
inclinations of the teeth are usually described ininclinations of the teeth are usually described in
terms of the angles between the long axis of aterms of the angles between the long axis of a
tooth and a line drawn perpendicular to thetooth and a line drawn perpendicular to the
horizontal plane or the median plane.horizontal plane or the median plane.
MesioMesio
distaldistal
88
1414
1010
1010
55
99
99
66
1717
66
77
00
22
22
FacioFacio
linguallingual
1010
2020
88
2020
66
99
55
99
1616
1212
2626
2323
2828
2222www.indiandentalacademy.comwww.indiandentalacademy.com

Inclination of teeth in proximal viewwww.indiandentalacademy.comwww.indiandentalacademy.com

Functional Form Of Teeth At TheirFunctional Form Of Teeth At Their
Incisal Or Occlusal ThirdIncisal Or Occlusal Third
The incisal and occlusal thirds of the toothThe incisal and occlusal thirds of the tooth
crowns present convex or concavecrowns present convex or concave
surfaces at all contacting occlusal areas.surfaces at all contacting occlusal areas.
When the teeth of one jaw come intoWhen the teeth of one jaw come into
contact with their antagonist in thecontact with their antagonist in the
opposite jaw during various mandibularopposite jaw during various mandibular
movements. Curved surfaces come intomovements. Curved surfaces come into
contact with curved surfaces.contact with curved surfaces.

Facial And Lingual Relations Of Each ToothFacial And Lingual Relations Of Each Tooth
In One Arch To Its Antagonist OrIn One Arch To Its Antagonist Or
Antagonists In The Opposing Arch InAntagonists In The Opposing Arch In
Centric OcclusionCentric Occlusion..
• In ICP, each tooth of one arch is inIn ICP, each tooth of one arch is in
occlusion with portions of two other teethocclusion with portions of two other teeth
in the opposing archin the opposing arch except mandibularexcept mandibular
central incisor and maxillary third molarcentral incisor and maxillary third molar..
• This helps to equalize the forces of impactThis helps to equalize the forces of impact
in occlusion and to distribute the work ofin occlusion and to distribute the work of
teeth evenly thereby preserving theteeth evenly thereby preserving the
integrity of the arch.integrity of the arch.

Occlusal Contacts And IntercuspalOcclusal Contacts And Intercuspal
Relations Of All The Teeth Of One ArchRelations Of All The Teeth Of One Arch
With Those In The Opposing Arch InWith Those In The Opposing Arch In
Centric OcclusionCentric Occlusion
The areas of occlusal contact thatThe areas of occlusal contact that
supporting cusps make with opposingsupporting cusps make with opposing
teeth in centric occlusion are called centricteeth in centric occlusion are called centric
stops. The areas of occlusal contact onstops. The areas of occlusal contact on
the supporting cusps that makes contactthe supporting cusps that makes contact
with opposing tooth in centric occlusion iswith opposing tooth in centric occlusion is
also called centric stops. It providesalso called centric stops. It provideswww.indiandentalacademy.comwww.indiandentalacademy.com

Lingual surface of maxillary incisors and caninesLingual surface of maxillary incisors and canines 66
Labial surface of mandibular incisors andLabial surface of mandibular incisors and
caninescanines
66
Triangular ridges of maxillary buccal cusps ofTriangular ridges of maxillary buccal cusps of
premolars and molarspremolars and molars
1616
Triangular ridges of lingual cusps of mandibularTriangular ridges of lingual cusps of mandibular
premolars and molarspremolars and molars
1616
Buccal embrasure of mandibular premolars andBuccal embrasure of mandibular premolars and
molarsmolars
88
Lingual embrasures of maxillary premolars andLingual embrasures of maxillary premolars and
molarsmolars
1010
Concept Of 138 Points Of Occlusal Contact)

Lingual cusp points of maxillary premolarsLingual cusp points of maxillary premolars
and molarsand molars
1616
buccal cusp points of mandibular premolarsbuccal cusp points of mandibular premolars
and molarsand molars
1616
Distal fossae of premolarsDistal fossae of premolars 88
Central fossae of molarsCentral fossae of molars 1212
Mesial fossae of mandibular molarsMesial fossae of mandibular molars 66
Distal fossae of maxillary molarsDistal fossae of maxillary molars 66
Lingual grooves of maxillary molarsLingual grooves of maxillary molars 66
Buccal grooves of mandibular molarsBuccal grooves of mandibular molars 66

Occlusal Contacts And Intercuspal RelationsOcclusal Contacts And Intercuspal Relations
Of All The Teeth Of One Arch With Those InOf All The Teeth Of One Arch With Those In
The Opposing Arch In Various MandibularThe Opposing Arch In Various Mandibular
MovementsMovements
There are 4 types of mandibularThere are 4 types of mandibular
movements:movements:
1.1. Laterotrusion ( working side movements)Laterotrusion ( working side movements)
2.2. Mediotrusion ( non working sideMediotrusion ( non working side
movements)movements)
3.3. Protrusive movementsProtrusive movements
4.4. Lateroprotrusive movements.Lateroprotrusive movements.

Neuromuscular Aspect OfNeuromuscular Aspect Of
OcclusionOcclusion
It includes function and parafunction of theIt includes function and parafunction of the
stomatognathic system.stomatognathic system.
FunctionFunction includes chewing, sucking, swallowing,includes chewing, sucking, swallowing,
speech and respiration.speech and respiration.
ParafunctionParafunction includes bruxism ( clenching andincludes bruxism ( clenching and
grinding )grinding )
All these function involve a greater coordinationAll these function involve a greater coordination
that is ultimately controlled by the centralthat is ultimately controlled by the central
nervous system.nervous system.

Occlusal stabilityOcclusal stability
It refers to tendency of the teeth , jaws joints andIt refers to tendency of the teeth , jaws joints and
muscles to remain in an optimal functional state.muscles to remain in an optimal functional state.
The stability of the occlusion and the maintenanceThe stability of the occlusion and the maintenance
of the tooth position are dependent on all theof the tooth position are dependent on all the
forces that acts on the teeth.forces that acts on the teeth.
Occlusal forces, eruptive forces, lip and cheekOcclusal forces, eruptive forces, lip and cheek
pressure , periodontal support and the tonguepressure , periodontal support and the tongue
pressure are all involved in maintaining thepressure are all involved in maintaining the
position of the teethposition of the teeth

• These are a set of six characteristicsThese are a set of six characteristics
that were consistently present inthat were consistently present in
collection of 120 casts of naturallycollection of 120 casts of naturally
optimal occlusion, identified by Dr.optimal occlusion, identified by Dr.
Lawrence F Andrews.Lawrence F Andrews.
Andrews six keys to normalAndrews six keys to normal
occlusionocclusion

Key I : Interarch RelationshipsKey I : Interarch Relationships
• The mesiobuccal cusp of the permanentThe mesiobuccal cusp of the permanent
maxillary first molar occludes in themaxillary first molar occludes in the
groove between the mesial and middlegroove between the mesial and middle
buccal cusps of the permanentbuccal cusps of the permanent
mandibular first molar.mandibular first molar.
• The distal marginal ridge of the maxillaryThe distal marginal ridge of the maxillary
first molar occludes with the mesialfirst molar occludes with the mesial
marginal ridge of the mandibular secondmarginal ridge of the mandibular second
molar.molar.

• The mesiolingual cusp of the maxillaryThe mesiolingual cusp of the maxillary
first molar occludes in the central fossafirst molar occludes in the central fossa
of the mandibular first molar.of the mandibular first molar.
• The buccal cusps of the maxillaryThe buccal cusps of the maxillary
premolars have a cusp embrasurepremolars have a cusp embrasure
relationship with the mandibularrelationship with the mandibular
premolars.premolars.
• The lingual cusps of the maxillaryThe lingual cusps of the maxillary
premolar have a cusp fossa relationshippremolar have a cusp fossa relationship
with the mandibular premolarswith the mandibular premolarswww.indiandentalacademy.comwww.indiandentalacademy.com

• The maxillary canine has a cuspThe maxillary canine has a cusp
embrasure relationship with theembrasure relationship with the
mandibular canine and first premolar. Themandibular canine and first premolar. The
tip of its cusp is slightly mesial to thetip of its cusp is slightly mesial to the
embrasure.embrasure.
• The maxillary incisors overlap theThe maxillary incisors overlap the
mandibular incisors and the midlines of themandibular incisors and the midlines of the
arches matcharches match

KeyII:MesioDistal CrownKeyII:MesioDistal Crown
AngulationAngulation
• Essentially all crowns in the sample haveEssentially all crowns in the sample have
a positive angulations (The gingivala positive angulations (The gingival
portion of the long axis of crown is moreportion of the long axis of crown is more
distal than the incisal portion)distal than the incisal portion)

Key III :LabioLingual CrownKey III :LabioLingual Crown
inclinationinclination
• Most maxillary incisors have a positiveMost maxillary incisors have a positive
inclination; mandibular incisors have ainclination; mandibular incisors have a
slightly negative inclination.slightly negative inclination.
• The inclinations of the maxillary incisorThe inclinations of the maxillary incisor
crowns are generally positive, thecrowns are generally positive, the
centrals more positive than the laterals.centrals more positive than the laterals.

• The Canines and premolars are negativeThe Canines and premolars are negative
and quite similar. The inclinations of theand quite similar. The inclinations of the
maxillary first and second molars are alsomaxillary first and second molars are also
similar and negative, but slightly moresimilar and negative, but slightly more
negative than those of the canines andnegative than those of the canines and
premolars.premolars.
• inclinations of the mandibular crowns areinclinations of the mandibular crowns are
progressively more negative from theprogressively more negative from the
incisors through the second molarsincisors through the second molars

Key IV: RotationsKey IV: Rotations
• Absence of rotations.Absence of rotations.

Key V: Tight ContactsKey V: Tight Contacts
• Contact points should abut unless aContact points should abut unless a
discrepancy exists in mesio-distal crowndiscrepancy exists in mesio-distal crown
diameter.diameter.

Key VI : Curve of SpeeKey VI : Curve of Spee
• The depth of theThe depth of the
curve of Spee rangescurve of Spee ranges
from a flat plane tofrom a flat plane to
slightly concaveslightly concave
surface.surface.

Occlusal principles inOcclusal principles in
orthodonticsorthodontics
Morphological requirements of a treatedMorphological requirements of a treated
case require :-case require :-
• Class I molar and canine.Class I molar and canine.
• Midlines should match.Midlines should match.
• Optimal amount of over jetOptimal amount of over jet
• Optimal amount of overbite.Optimal amount of overbite.
• Arch forms should be coordinated andArch forms should be coordinated and
close to original arch form.close to original arch form.

• Optimal tooth angulations and inclination.Optimal tooth angulations and inclination.
• Absence of malalignment, crowding ,Absence of malalignment, crowding ,
rotations.rotations.
• Absence of spacing.Absence of spacing.
• Absence of marginal ridge discrepancy.Absence of marginal ridge discrepancy.
• Mild curve of Spee and Wilson.Mild curve of Spee and Wilson.
• Roots of teeth should be parallel.Roots of teeth should be parallel.
• Supporting cusps of posterior teeth shouldSupporting cusps of posterior teeth should
occlude with marginal ridge or central fossaocclude with marginal ridge or central fossa
of opposing teeth.of opposing teeth.

• Smooth gliding excursions in all theSmooth gliding excursions in all the
directions.directions.
• Distribution of forces along the long axis.Distribution of forces along the long axis.
• Anterior guidance.Anterior guidance.
• Canine guidance/group function.Canine guidance/group function.
• In lateral movement disclusion of allIn lateral movement disclusion of all
nonworking side teeth.nonworking side teeth.
• CO coincident with CR.CO coincident with CR.

ConclusionConclusion
Attainment of a normal occlusion shouldAttainment of a normal occlusion should
not be an orthodontist’s goal. Rather,not be an orthodontist’s goal. Rather,
proper harmonious inter-relationship withproper harmonious inter-relationship with
surrounding structures must be the endsurrounding structures must be the end
result.result.
Final occlusion should be morphologicallyFinal occlusion should be morphologically
and functionally optimal for the individual.and functionally optimal for the individual.

THANK YOU

FLUSH TERMINALFLUSH TERMINAL
• If the mesiodistal crownIf the mesiodistal crown
Of the mandibular 2Of the mandibular 2ndnd
dec.dec.
Molar is a few mm largerMolar is a few mm larger
Than the opposing max.Than the opposing max.
Molar, the terminal plane isMolar, the terminal plane is
FLUSH.FLUSH.
After emergence the 1After emergence the 1stst
Permanent molars getPermanent molars get
Oriented in anOriented in an END TOEND TO
ENDEND position.position.

Primary occlusionPrimary occlusion
The normal occlusion of theThe normal occlusion of the
primary teeth at the age ofprimary teeth at the age of
three years is as follows:three years is as follows:
1.1. Mesial surfaces of maxillaryMesial surfaces of maxillary
and mandibular centraland mandibular central
incisors are in line with eachincisors are in line with each
other at the median line.other at the median line.
2.2. The maxillary central incisorThe maxillary central incisor
occludes with the mandibularoccludes with the mandibular
central incisor and mesial thirdcentral incisor and mesial third
of the mandibular lateralof the mandibular lateral
incisor. The mandibularincisor. The mandibular
anterior teeth strike theanterior teeth strike the
maxillary anterior teethmaxillary anterior teeth
lingually above the level of thelingually above the level of the
incisal ridges.incisal ridges. www.indiandentalacademy.comwww.indiandentalacademy.com

HOW?HOW?
• 1)Early mesial shift1)Early mesial shift
• 2)Late mesial shift2)Late mesial shift
• 3)Greater forward growth of the mandible3)Greater forward growth of the mandible
than the maxilla.than the maxilla.
• 4)Combination of the above.4)Combination of the above.

ANTHROPOID/SIMIANANTHROPOID/SIMIAN
SPACESSPACES

EARLYEARLY MESIALMESIAL SHIFTSHIFT
• If the dec. dentition is spaced with a flushIf the dec. dentition is spaced with a flush
terminal relation of the 2terminal relation of the 2ndnd
dec. molar, thendec. molar, then
the eruptive force of the 1the eruptive force of the 1stst
permanentpermanent
molar causes the closing of any existingmolar causes the closing of any existing
spaces.spaces.
• Closure of theClosure of the PRIMATE SPACES.PRIMATE SPACES.
• Mesial to the dec. canine in the max.Mesial to the dec. canine in the max.
arch and distal to the dec. canine inarch and distal to the dec. canine in
the mandiular arch.the mandiular arch.www.indiandentalacademy.comwww.indiandentalacademy.com

LATE MESIALLATE MESIAL SHIFTSHIFT
• When no spaces exist the erupting 1When no spaces exist the erupting 1stst
molar migrates mesially to use upmolar migrates mesially to use up
thethe LEEWAY SPACE.LEEWAY SPACE.
• The difference between theThe difference between the
mesiodistal width of themesiodistal width of the
primary canine,1primary canine,1stst
molar,2molar,2ndnd
molar and their permanentmolar and their permanent
successors.successors.
• Maxilla:1.8mmMaxilla:1.8mm
• Mandible:3.4mmMandible:3.4mm

DIFFERENTIAL GROWTH OFDIFFERENTIAL GROWTH OF
THE MAXILLA AND MANDIBLETHE MAXILLA AND MANDIBLE
• Rate: Growth between the maxilla and theRate: Growth between the maxilla and the
mandible is not the same.mandible is not the same.
• The growth of the mandible is twice that of theThe growth of the mandible is twice that of the
maxilla during development of dentition.maxilla during development of dentition.
• Shift which brings the mandible forward causingShift which brings the mandible forward causing
the END TO END molar relation of the mixedthe END TO END molar relation of the mixed
dentition to change into a class1 in thedentition to change into a class1 in the
permanent dentition.permanent dentition.

DOMINENCE OF SKELETALDOMINENCE OF SKELETAL
PATTERNPATTERN
• MOYERS AND WAINRIGHTMOYERS AND WAINRIGHT
• Eg. FLUSH TERMINAL with a greater verticalEg. FLUSH TERMINAL with a greater vertical
growth of the maxilla.growth of the maxilla.
The mandible would be forced to rotate downwardThe mandible would be forced to rotate downward
and backward. Rotation would prevent attainmentand backward. Rotation would prevent attainment
of normal cuspal interdigitaion.of normal cuspal interdigitaion.

• Occlusal changesOcclusal changes :-:-
• Overbite and over jet decreases throughout theOverbite and over jet decreases throughout the
second decade of life (forward growth ofsecond decade of life (forward growth of
mandible )mandible )
• Posterior occlusal changes are due to the mesialPosterior occlusal changes are due to the mesial
drifting tendency, slight interproximal wear anddrifting tendency, slight interproximal wear and
continuing growth of mandible.continuing growth of mandible.

Characteristics of occlusionCharacteristics of occlusion
• Alignment of teeth :-Alignment of teeth :-
• Alignment of dentition in arch occurs as aAlignment of dentition in arch occurs as a
result of multidirectional forces acting onresult of multidirectional forces acting on
the teeth during and after eruption.the teeth during and after eruption.
• Equilibrium position of opposing forcesEquilibrium position of opposing forces
that are lips and cheeks from outer sidethat are lips and cheeks from outer side
and tongue from inner side determine theand tongue from inner side determine the
(stable) position of the teeth(stable) position of the teeth

Equilibrium position ofEquilibrium position of
dentitiondentition

• Intra arch tooth alignmentIntra arch tooth alignment :-:-
• Relationship of teeth with in the dental arch.Relationship of teeth with in the dental arch.
• Teeth are placed in dental arch in varyingTeeth are placed in dental arch in varying
degree of inclination.degree of inclination.
• In maxillary arch anterior teeth are mesiallyIn maxillary arch anterior teeth are mesially
inclined and most posterior teeth are distallyinclined and most posterior teeth are distally
inclined.inclined.

• Inter arch tooth alignmentInter arch tooth alignment :-:-
• Relationship of teeth in one arch to those inRelationship of teeth in one arch to those in
other arch.other arch.
• Mandibular arch length and width is slightlyMandibular arch length and width is slightly
less than maxillary arch.less than maxillary arch.

• Proximal contact area are generally locatedProximal contact area are generally located
slightly buccal to the CF line allowingslightly buccal to the CF line allowing
greater lingual embrasure area and smallergreater lingual embrasure area and smaller
buccal embrasure area ( spillway for food )buccal embrasure area ( spillway for food )

Normal Occlusion Characteristics

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Normal Occlusion Characteristics