Normal occlusion (2)

NORMAL OCCLUSIONNORMAL OCCLUSION
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Normal occlusionNormal occlusion
OcclusionOcclusion
Oc-upOc-up
Clusion: closingClusion: closing
Thus occlusion means closingThus occlusion means closing
up.up.
The definition of the termThe definition of the term
occlusion in many dictionariesocclusion in many dictionaries
only states that it is the act ofonly states that it is the act of
closure or being closedclosure or being closed..

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.

Occlusion is a complex phenomenon involvingOcclusion is a complex phenomenon involving
the teeth, periodontal ligaments the jaws thethe teeth, periodontal ligaments the jaws the
temporomandibular joint, the muscles and thetemporomandibular joint, the muscles and the
nervous system.nervous system.
When the jaws are closed and the heads of theWhen the jaws are closed and the heads of the
condyles are in the resting position in thecondyles are in the resting position in the
glenoid fossa the cusps , fossae and incisalglenoid fossa the cusps , fossae and incisal
edges of individual teeth of the upper andedges of individual teeth of the upper and
lower arches comes into contact with onelower arches comes into contact with one
another, the sum of these relations make upanother, the sum of these relations make up
the occlusion of the dentition.the occlusion of the dentition.

AspectsAspects
of occlusionof 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.teeth to their supporting structure.
 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.

TerminologyTerminology
1.Gnathology1.Gnathology::
It is the science of mandibular movementsIt is the science of mandibular movements
and resultant occlusal contacts.and resultant occlusal contacts.

2. Ideal Occlusion2. Ideal 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.

3. Physiologic occlusion3. Physiologic occlusion:-:-
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.

4. Balanced occlusion4. Balanced 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 , in the anterior and posteriorand left , in the anterior and posterior
occlusal areas when the jaws are either inocclusal areas when the jaws are either in
centric or eccentric occlusion.centric or eccentric occlusion.

5. Functional occlusion5. Functional 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.

6.Therapeutic occlusion6.Therapeutic 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.

7.Traumatic occlusion7.Traumatic 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

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

Supporting cusps /Centric holding cups/stamp cupsSupporting cusps /Centric holding cups/stamp cups
The buccal cusps of mandibular and palatal cups ofThe buccal cusps of mandibular and palatal cups of
maxillary posterior teeth are called stamp cusps.maxillary posterior teeth are called stamp cusps.
They occlude into the central fossae and marginalThey occlude into the central fossae and marginal
ridges of opposing teeth.ridges of opposing teeth.
Non-supporting cusps/Shearing cusps or guidingNon-supporting cusps/Shearing cusps or guiding
cuspscusps
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. They contact and guide the mandiblecusps. They contact and guide the mandible
during lateral excursion and shear food duringduring lateral excursion and shear food during
mastication.mastication.

Imaginary occlusal planesImaginary occlusal planes
and curvesand curves
1. Curve of Spee1. Curve of Spee:-:-
It refers to the anterior-It refers to the anterior-
posterior curvature of theposterior curvature of the
occlusal surface beginningocclusal surface beginning
at the tip of the lowerat the tip of the lower
cuspid and following thecuspid and following the
cusps tip of the bicuspidscusps tip of the bicuspids
and molars continuing asand molars continuing as
an arc through thean arc through the
condyle. If the curve iscondyle. If the curve is
extended, it would form aextended, it would form a
circle of about 4 inchcircle of about 4 inch
diameter.diameter.

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.

2. Curve of Wilson2. Curve of Wilson:-:-
This is a curve thatThis is a curve that
contacts the buccal andcontacts the buccal and
lingual cusps tips oflingual cusps tips of
the mandibularthe mandibular
posterior teeth. Theposterior teeth. The
curve of Wilson iscurve of Wilson is
medio-lateral on eachmedio-lateral on each
side of the arch. Itside of the arch. It
results from the inwardresults from the inward
inclination of lowerinclination of lower
posterior teeth.posterior teeth.

This curve helps in twoThis curve helps in two
ways:-ways:-
A) Teeth are alignedA) Teeth are aligned
parallel to the directionparallel to the direction
of medial pterygoid forof medial pterygoid for
optimum resistance tooptimum resistance to
masticatory forces.masticatory forces.
B) The elevated buccalB) The elevated buccal
cusps prevent food fromcusps prevent food from
going past the occlusalgoing past the occlusal
table.table.

3. Curve of Monson3. Curve of Monson:-:-
It is obtained by extending the Curve ofIt is obtained by extending the Curve of
Spee and Curve of Wilson to all cuspsSpee and Curve of Wilson to all cusps
and incisal edges.and incisal edges.

Centric RelationCentric Relation
Centric relationCentric relation is the relationis the relation
of the mandible to theof the mandible to the
maxilla when themaxilla when the
mandibular condyles are inmandibular condyles are in
most superior and retrudedmost superior and retruded
position in their glenoidposition in their glenoid
fossa with the articular discfossa with the articular disc
properly interposed. Centricproperly interposed. Centric
relation is also called asrelation is also called as
ligamentous positionligamentous position oror
terminal hinge position.terminal hinge position.

Centric OcclusionCentric Occlusion
Centric occlusionCentric occlusion is thatis that
position of mandibularposition of mandibular
condyle when jaws arecondyle when jaws are
closed and the teeth areclosed and the teeth are
in maximumin maximum
intercuspation. Centricintercuspation. Centric
occlusion is also calledocclusion is also called
asas Inter-cuspal positionInter-cuspal position
oror convenienceconvenience
occlusionocclusion..

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. Studies have shownand neuromuscular system. Studies have shown
that majority of the population have a maximumthat majority of the population have a maximum
intercuspation 1-2 mm forwards of centricintercuspation 1-2 mm forwards of centric
relation.relation.
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
This position is obtained when all the jaw musclesThis position is obtained when all the jaw muscles
are at rest. This position depends on restingare at rest. This position depends on resting
muscle tone, in this position the upper and lowermuscle tone, in this position the upper and lower
jaws are not in contact and the space betweenjaws are not in contact and the space between
the upper and lower teeth is called as thethe upper and lower teeth is called as the
freeway spacefreeway space . This measures on average 2-5. This measures on average 2-5
mm at the incisal area. The lips are generallymm at the incisal area. The lips are generally
closed during this position. It is constantclosed during this position. It is constant
throughout life and is not dependent on thethroughout life and is not dependent on the
presence or absence of teeth. All functionalpresence or absence of teeth. All functional
movements begin and end with rest position.movements begin and end with rest position.

Centric ContactCentric Contact
They are the areas of the teeth that contact theThey are the areas of the teeth that contact the
opposing teeth.opposing teeth.
There are two types of centric contacts:There are two types of centric contacts:
Posterior centric contactsPosterior centric contacts:-:-
Posterior centric contacts consists of the facial range ofPosterior centric contacts consists of the facial range of
contacts and lingual range or contacts.contacts and lingual range or contacts.
 Facial range of posterior centric contactFacial range of posterior centric contact involveinvolve
mandibular facial cusps tips contacting centralmandibular facial cusps tips contacting central
fossae and mesial marginal ridges of the opposingfossae and mesial marginal ridges of the opposing
maxillary teeth.maxillary teeth.
 Lingual range of posterior centric contactLingual range of posterior centric contact involvesinvolves
the maxillary lingual cusps tips contacting thethe maxillary lingual cusps tips contacting the
central fossae and distal marginal ridges of thecentral fossae and distal marginal ridges of the
opposing mandibular teeth.opposing mandibular teeth.

Anterior centric contact sAnterior centric contact s:-:-
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.
Centric contacts often occurs on inclines ofCentric contacts often occurs on inclines of
posterior teeth. These contacts that occurs onposterior teeth. These contacts that occurs on
one incline are calledone incline are called poded centric contactpoded centric contact. If. If
contact occurs between two inclines the contactcontact occurs between two inclines the contact
is termed bipoded contact. If contact occurs on 3is termed bipoded contact. If contact occurs on 3
inclines it is called tripoded contacts and Ifinclines it is called tripoded contacts and If
contact occurs on 4 inclines it is calledcontact occurs 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.

Functional occlusionFunctional occlusion:-:-
Functional occlusionFunctional occlusion also called working side occlusionalso called working side occlusion
refers to tooth contact that occur in the segment of therefers to tooth contact that occur in the segment of the
arch towards which the mandible moves.arch towards which the mandible moves.
Two typesTwo types::
I)I) Lateral functional occlusionLateral functional occlusion:-:-
It includes tooth contacts that occur on canine andIt includes tooth contacts that occur on canine and
posterior teeth on the side towards which the mandibleposterior teeth on the side towards which the mandible
moves. It is also of two types:moves. It is also of two types:
i)i) Canine guided occlusionCanine guided occlusion:-:-
During the lateral mandibular movements, the opposingDuring the lateral mandibular movements, the opposing
upper and lower canines of working side contact therebyupper and lower canines of working side contact thereby
causing disclusion of all posterior teeth on the workingcausing disclusion of all posterior teeth on the working
and balancing sides. Canine guided occlusion is usuallyand balancing sides. Canine guided occlusion is usually
seen in young individual with unworn dentition.seen in young individual with unworn dentition.

Canine guidance in right and left
laterotrusion

ii)ii) Grouped lateral occlusionGrouped lateral occlusion:-:-
In addition to canine guidance, certainIn addition to canine guidance, certain
other posterior teeth on the workingother posterior teeth on the working
side also contact during lateralside also contact during lateral
movement of mandible, such type ofmovement of mandible, such type of
contact during lateral movement iscontact during lateral movement is
called grouped lateral occlusion.called grouped lateral occlusion.
II)II) Protrusive functional occlusionProtrusive functional occlusion:-:-
Includes eccentric contacts that occursIncludes eccentric contacts that occurs
when the mandible moves forward.when the mandible moves forward.
Ideally six mandibular anterior teethIdeally six mandibular anterior teeth
contact along the lingual inclines ofcontact along the lingual inclines of
the maxillary anterior teeth while thethe maxillary anterior teeth while the
posterior disocclude.posterior disocclude.
b)b) Non functional occlusionNon functional occlusion:-:-
They are tooth contact that occur in theThey are tooth contact that occur in the
segment away from which thesegment away from which the
mandible moves.mandible moves.

DisclusionDisclusion:-:-
Term is used to describe disocclusion orTerm is used to describe disocclusion or
separation of non functional posteriorseparation of non functional posterior
teeth during eccentric motions of the jaw .teeth during eccentric motions of the jaw .
Disclusion of posterior teeth is broughtDisclusion of posterior teeth is brought
about byabout by condylar guidancecondylar guidance andand incisalincisal
guidance.guidance.

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. In case ofseparation of the posteriors. In case of
lateral movements, the condyles on thelateral movements, the condyles on the
non-functioning side translates forwardnon-functioning side translates forward
along the eminence while the condyle onalong the eminence while the condyle on
the functioning side pivots in its fossathe functioning side pivots in its fossa
leading to disclusion of posterior teeth onleading to disclusion of posterior teeth on
the non-functional side.the non-functional side.

Anterior guidance/IncisalAnterior guidance/Incisal
guidanceguidance refers to anteriorrefers to anterior
tooth functions whichtooth functions which
separates the posteriorseparates the posterior
teeth during eccentricteeth during eccentric
motions of the jaw. Duringmotions of the jaw. During
protrusive and lateralprotrusive and lateral
movement of themovement of the
mandible, the lowermandible, the lower
anterior teeth tracesanterior teeth traces
downward from their areadownward from their area
of centric contact towardsof centric contact towards
the incisal edges ofthe incisal edges of
maxillary teeth whilemaxillary teeth while
disoccluding the non-disoccluding the non-
functional posterior teeth.functional posterior teeth.

Canine and central incisor guidance contacts
in centric relation

Condylar guidance has its greatest influenceCondylar guidance has its greatest influence
on discluding the most distal posterioron discluding the most distal posterior
teeth while incisal guidance providesteeth while incisal guidance provides
discluding effect on the more mesial teeth.discluding effect on the more 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.

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 occlusion theIn this type of occlusion the
stamp cusp of one toothstamp cusp of one tooth
occludes in a single fossaoccludes in a single fossa
of a single opponent. Theof a single opponent. The
upper stamp cusps fit intoupper stamp cusps fit into
all except the mesialall except the mesial
fossa of the lower teethfossa of the lower teeth
while lower stamp cuspswhile lower stamp cusps
fit into all the upper fossafit into all the upper fossa
except the distal ones ofexcept the distal ones of
bicuspids.bicuspids.
This kind of arrangementThis kind of arrangement
where contact occurswhere contact occurs
between single opposingbetween single opposing
teeth is calledteeth is called a cuspa cusp
fossa occlusion or a toothfossa occlusion or a tooth
to tooth arrangementto 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

Normal occlusionNormal occlusion
““ Normal” means absence of any disease withNormal” means absence of any disease with
functional adaptability and capability of thefunctional adaptability and capability of the
masticatory system to compensate for anymasticatory system to compensate for any
deviation within the range of tolerance.deviation within the range of tolerance.
AA normal occlusionnormal occlusion considers occlusal contacts,considers occlusal contacts,
alignment of teeth, overbite , overjet,alignment of teeth, overbite , overjet,
arrangement and relationship of teeth withinarrangement and relationship of teeth within
and between the arches, relationship of theand between the arches, relationship of the
teeth to osseous structures and relations of theteeth to osseous structures and relations of the
neuromuscular mechanism to the occlusion.neuromuscular mechanism to the occlusion.

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

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.

Permanent occlusionPermanent occlusion
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 tooth in one6. Facial and lingual relations of each tooth in one
arch to its antagonist or antagonists in thearch to its antagonist or antagonists in the
opposing arch in centric occlusion.opposing arch in centric occlusion.
7. Occlusal contacts and intercuspal relations of all7. Occlusal contacts and intercuspal relations of all
the teeth of one arch with those in thethe teeth of one arch with those in the
opposing arch in centric occlusion.opposing arch in centric occlusion.
8. Occlusal contacts and intercuspal relations of all8. Occlusal contacts and intercuspal relations of all
the teeth of one arch with those in thethe teeth of one arch with those in the
opposing arch in various mandibularopposing arch in various mandibular
movements.movements.
9. Neuromuscular aspect of occlusion.9. Neuromuscular aspect of occlusion.

Dental arch formDental arch form
 From occlusal aspect theFrom occlusal aspect the
dental arches aredental arches are
parabolic in shape. Theparabolic in shape. The
shape is determined byshape is determined by
underlying basal bone.underlying basal bone.
 Maxillary arch >Maxillary arch >
Mandibular arch.Mandibular arch.
 AdvantagesAdvantages::
1.1. Protects lips , cheek andProtects lips , cheek and
tongue during the openingtongue during the opening
and closing movements.and closing movements.
2.2. Provides stability therebyProvides stability thereby
preventing tooth migration.preventing tooth migration.

Compensating curvatures of dentalCompensating curvatures of dental
archesarches
 Mandibular archMandibular arch
conforms to aconforms to a
curved plane whichcurved plane which
appears concaveappears concave
and maxillary archand maxillary arch
appears convex.appears convex.
i)i) Curve of Spee.Curve of Spee.
ii)ii) Curve of Wilson.Curve of Wilson.
iii)iii) Curve of Manson.Curve of Manson.

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 teethAngulations and inclination of teeth
in relation to various planesin relation to various planes
 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 axes of aterms of the angles between the long axes 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

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 arch except mandibularin the opposing arch except mandibular
central incisor and maxillary third molar.central incisor and maxillary third molar.
This helps to equalize the forces of impact inThis helps to equalize the forces of impact in
occlusion and to distribute the work ofocclusion 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 that supportingThe areas of occlusal contact that supporting
cusps make with opposing teeth in centriccusps make with opposing teeth in centric
occlusion are called centric stops. The areas ofocclusion are called centric stops. The areas of
occlusal contact on the supporting cusps thatocclusal contact on the supporting cusps that
makes contact with opposing tooth in centricmakes contact with opposing tooth in centric
occlusion is also called centric stops. It providesocclusion is also called centric stops. It provides
occlusal stability.occlusal stability.

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

 Andrews six keys to normal occlusion:-Andrews six keys to normal occlusion:-
1.1. Molar interarch relationship,Molar interarch relationship,
2.2. Mesio-distal crown angulation,Mesio-distal crown angulation,
3.3. Labio-lingual crown inclination,Labio-lingual crown inclination,
4.4. Absence of rotation,Absence of rotation,
5.5. Tight contacts,Tight contacts,
6.6. Curve of spee.Curve of spee.

 1) MOLAR INTERARCH RELATIONSHIP:-1) MOLAR INTERARCH RELATIONSHIP:-
 Mesio –buccal cusp of upper first molar shouldMesio –buccal cusp of upper first molar should
occlude in the buccal groove between the mesial andocclude in the buccal groove between the mesial and
medial buccal cusp of the lower first molar.medial buccal cusp of the lower first molar.
 The mesio-lingual cusp of the upper first molar shouldThe mesio-lingual cusp of the upper first molar should
occlude In the central fossa of lower first molar.occlude In the central fossa of lower first molar.
 The crown of upper first molar must be angulated soThe crown of upper first molar must be angulated so
that the distal marginal ridge occlude with mesialthat the distal marginal ridge occlude with mesial
marginal ridge of the lower second molar.marginal ridge of the lower second molar.

 2) MESO-DISTAL CROWN ANGULATION:-2) MESO-DISTAL CROWN ANGULATION:-
 A line that passes alonght the long axis of theA line that passes alonght the long axis of the
crown through the most prominent part in thecrown through the most prominent part in the
center of the labial or buccal surface is calledcenter of the labial or buccal surface is called
the long axis of the clinical crown.the long axis of the clinical crown.
 For the normal occlusion the gingival part of theFor the normal occlusion the gingival part of the
long axis the crown must be distal to occlusallong axis the crown must be distal to occlusal
part of the line.part of the line.

 LABIO-LINGUAL CROWN INCLINATION :-LABIO-LINGUAL CROWN INCLINATION :-
 The crown inclination is determined from a Mesial orThe crown inclination is determined from a Mesial or
distal view.distal view.
 If the gingival area of the crown is more linguallyIf the gingival area of the crown is more lingually
placed than the occlusal area, it is referred to asplaced than the occlusal area, it is referred to as
positive crown inclination.positive crown inclination.
 In the case the gingival area of the crown is moreIn the case the gingival area of the crown is more
labially or buccally placed than the occlusal area , itlabially or buccally placed than the occlusal area , it
is referred to asis referred to as negative crown inclination.negative crown inclination.
 The maxillary incisor exhibits a positive crownThe maxillary incisor exhibits a positive crown
inclination, while the mandibular incisors show ainclination, while the mandibular incisors show a
very mild negative crown inclination.very mild negative crown inclination.
 All the maxillary and mandibular posterior have aAll the maxillary and mandibular posterior have a
negative crown inclination.negative crown inclination.

 4)ABSENCE OF ROTATION:-4)ABSENCE OF ROTATION:-
 Normal occlusal is characterized by theNormal occlusal is characterized by the
absence of any rotation.absence of any rotation.
 Rotated posterior teeth occupy more space inRotated posterior teeth occupy more space in
dental arch while rotated incisors occupy lessdental arch while rotated incisors occupy less
space.space.

 5) TIGHT CONTACTS:-5) TIGHT CONTACTS:-
 To consider a occlusion as normal there shouldTo consider a occlusion as normal there should
be tight contacts between adjacent teeth.be tight contacts between adjacent teeth.

 6) CURVE OF SPEE:-6) CURVE OF SPEE:-
 A normal occlusal plane according to Andrew'sA normal occlusal plane according to Andrew's
should be flat , with the curve of SPEE notshould be flat , with the curve of SPEE not
exceeding 1.5mm.exceeding 1.5mm.

Normal occlusion (2)

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