Occlusion basics

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

OCCLUSION
• ANGLE defined occlusion as the normal
relation of the occlusal inclined planes of
the teeth when the jaws are closed.
• SHAW defined dental occlusion as the
static,closed contacting position of the
upper teeth to the lower teeth

TERMINOLOGY
• NORMAL OCCLUSION-in orthodontics is
ANGLES CLASS 1 OCCLUSION
The mesiobuccal cusp of the maxillary 1st
molar should occlude in the mesiobuccal
groove of the mandibular 1st
molar.
If this molar relationship existed and the teeth
were arranged on a smoothly curving line of
occlusion normal occlusion would result

• THE LINE OF OCCLUSION-is a
smooth curve passing through the
central fossa of each upper molar
and across the cingulum of the upper
canine and incisor teeth.
• The same line runs along the
buccal cusps and incisal edges of the
lower teeth,thus specifying occlusal
as well as interarch relationships
once the molar relation is
established.

IDEAL OCCLUSION
• Is a preconceived theoretical concept of
occlusal,structural and functional
relationships that includes idealized
principles and characteristics that an
ideal occlusion should have.

PHYSIOLOGIC
OCCLUSION
• This refers to an occlusion that
deviates in one or more ways from
ideal yet is well adapted to that
particular environment,is esthetic and
shows no pathologic manifestations or
dysfunction.

BALANCED OCCLUSION
• An occlusion in which balanced and
equal contacts are maintained
throughout the entire arch during all
excursions of the mandible.
• There is simultaneous contact of
maxillary and mandibular teeth on the
right and left ,in anterior and
posterior occlusal areas when the jaws
are either in centric or eccentric
occlusion.

FUNCTIONAL OCCLUSION
• It is defined as an arrangement of
teeth which will provide the highest
efficiency during all the excursive
movements of the mandible which are
necessary during function.

THERAPEUTIC OCCLUSION
• A n occlusion that has been modified
by appropriate therapeutic
modalities in order to change a non
physiologic occlusion to one that is at
least physiologic if not ideal.

TRAUMATIC OCCLUSION
Is an abnormal occlusal stress which is
capable of producing or has produced
an injury to the periodontium.

TRAUMA FROM OCCLUSION
• It is defined as periodontal tissue
injury caused by occlusal forces
through abnormal tissue contacts.

TYPES OF CUSPS
• CENTRIC HOLDING CUSPS
• The facial cusps of mandibular and palatal
cusps of maxillary posterior teeth are
called the centric holding cusps.They
occlude into the central fossa and marginal
ridges of opposing teeth.They are also
called the STAMP CUSPS.

• NON SUPPORTING CUSPS
• The maxillary buccal and mandibular
lingual cusps are called non
supporting cusps.They contact and
guide the mandible during lateral
excursions and shear food during
mastication.Hence they are called
SHEARING OR GUIDING CUSPS.

CLASSIFICATION OF
0CCLUSION
• BASED ON MANDIBULAR
POSITION
• CENRIC OCCLUSION-Is that
position of the mandibular condyle when
the teeth are in maximum
intercuspation.It is also called
INTERCUSPAL POSITION OR
CONVENIENCE OCCLUSION.

• ECCENTRIC OCCLUSION
• It is defined as the occlusion
other than centric occlusion.It
refers to contact of teeth that
occurs during movement of the
mandible.
• It includes:LATERAL
OCCLUSION RIGHT AND LEFT
LATERAL OCCLUSION

• It is defined as the contact between
opposing teeth(canines and posterior
teeth)when the mandible is moved right or
left of the midsaggital plane.The contacts
occur on the sides towards which the
mandible moves.
• PROTRUDED OCCLUSION:Defined as the
occlusion of the teeth when the mandible is
protruded.The position of the mandible is
anterior to centric relation.Ideally the six
anterior teeth contact along the lingual
inclines of the max. ant. teeth while the
posteriors disocclude.

• RETRUSIVE OCCLUSION
Occlusion of the teeth when the
mandible is retruded.It is the
position of the mandible posterior to
centric relation.

BASED ON THE
RELATIONSHIP OF THE 1ST
MOLAR
• NEUTRO-OCCLUSION/CLASS1
• The anteroposterior relationshipof the
maxillary and mandibular molars is
correct,with the mesiobuccal cusp of the
maxillary 1st
molar occluding in the
mesiobuccal groove of the mandibular ist
molar.

• DISTO OCCLUSION/CLASS2
• The lower dental arch is in a distal or
posterior relation to the upper dental
arch,as reflected by the 1st
permanent
molar relationship.The mesiobuccal groove
of the mandibular 1st
molar contacts the
distobuccal cusp of the maxillary 1st
molar
or it may be farther posterior.

• It is further subdivided into:
• DIV1:Bilateral distal retrusion with a
narrow maxillary arch and protruding
maxillary incisors.Increased overjet.
• DIV2:Bilateral distal retrusion with a
normal or square shaped maxillary
arch,retruded maxillary
centrals,labially malposed maxillary
laterals and an excessive overbite.

• MESIO-OCCLUSION/CLASS-3
• The mandibular 1st
molar is mesial to
the maxillary 1st
molar and the
mandibular incisors are in anterior
crossbite.

BASED ON THE ORGANIZATION
OF OCCLUSION
• A) CANINE GUIDED OR PROTECTED
OCCLUSION
• During lateral mandibular movements,the
opposing upper and lower canines of the
working side contact thereby causing
disclusion of all posterior teeth on the
working and balancing sides.This is because
the mandible moves away from centric
occlusion.

MUTUALLY PROTECTED
OCCLUSION
Occlusal scheme in which the posterior
teeth prevent excessive contact of
the anterior teeth in maximum
intercuspation.
Also,the anterior teeth
disengage the posterior
teeth in all mandibular
excursive movements.

GROUP FUNCTION
OCCLUSION
• Is defined as the multiple contact
relationship between maxillary and
mandibular teeth,in lateral
movements of the working side,where
by simultaneous contacts of several
teeth is achieved and they act as a
group to distribute forces.

BASED ON PATTERN OF
OCCLUSION
• A)CUSP TO EMBRASURE/MARGINAL
RIDGE
• Development of occlusion can result in fitting of
one stamp cusp into a fossa and the fitting of
another cusp of the same tooth into the embrasure
area of two opposing teeth.
• This is TOOTH-TO-
• TWO-TEETH
• relation occlusion.

• B)CUSP-FOSSA OCCLUSION
• In this type of occlusion,the stamp cusp of
one tooth occludes in a single fossa of a
single opponent.
• This is a tooth to one tooth relation.
• Has advantages over the cusp-embrasure
arrangement:
• A)Forces are directed more towards the
long axis.

• B)Arrangement leads to greater
stability of the arch,decreasing the
tendency towards tooth movement.
• C)The chances of food impaction in
the embrasure is less.

IMAGINARY CURVES
• A)CURVE OF SPEE-BY VON SPEE
• It refers to the anteroposterior curvature
of the occlusal surface,beginning at the tip
of the lower cuspid and following cusp tip
of bicuspids and molars continuing as an
arc through the condyle.
• If the curvature were extended,it would
form a circle about
• 4inches in dia.

• B)CURVE OF WILSON-
• It is a curve that contacts the buccal and
lingual cusp tips of mandibular posterior
teeth.
• It is mediolateral on each side of the arch
• It results from the inward inclination of
the lower posterior teeth.

CURVE OF MONSON
It is obtained by the extension of the
curve of spee and the curve of wilson
to all cusps and incisal edges.

CENTRIC RELATION
• Is the relation of the mandible to the
maxilla when the mandibular condyles
are in the most superior and retruded
position in their glenoid fossa with the
articular disc properly interposed.
• Also called LIGAMENTOUS OR
TERMINAL HINGE POSITION.
• Is a bone to bone relation.

ANDREWS KEYS OF
OCCLUSION
• A)MOLAR INTERARCH
RELATIONSHIP
• The mesiobuccal cusp of the upper first
molar should occlude in the groove between
the mesial and the medial buccal cusp of
the lower first molar.
• The mesiolingual cusp of the upper 1st
molar
should occlude in the central fossa of the
lower 1st
molar

• The crown of the upper first molar
must be angulated so that the distal
marginal ridge occludes with mesial
marginal ridge of the lower second
molar.

• MESIO DISTAL CROWN ANGULATION
• The 2nd
key makes use of a line that passes along
the long axis of the crown through the most
prominent part in the centre of the labial or
buccal surface.This is called the long axis of the
crown.
• The gingival part of the long axis of the crown
must be distal to the occlusal part of the line.

• LABIOLINGUAL CROWN
INCLINATION
• Determined from the mesial or the
distal view.
• If the gingival area of the crown is
more lingually placed than the occlusal
area,it is referred to as POSITIVE
CROWN INCLINATION.The maxillary
incisors exhibit this inclination.

• Incase the gingival area of the crown is
more labialy or buccally placed than the
occlusal area it is referred to as
NEGATIVE CROWN INCLINATION.
• Mandibular incisors exhibit mild –ve
inclination.
• Maxillary and mandibular posteriors
exhibit the same.

• CURVE OF SPEE-Should not
be exceeding 1.5mm.
•ABSENCE OF ROTATION
•TIGHT CONTACTS

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Occlusion basics

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