01 occlusion in prosthodontics introduction - stomatognathic system- definitions

Dr. Amal Fathy Kaddah
Prof. of Prosthodontic,
Faculty of Oral & Dental Medicine,
Cairo University

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• The stomatognathic system
• What 'occlusion' is and why it is important
• Definitions.
• The significance of 'ideal occlusion‘
• Difference between natural and artificial Occ.
• Mandibular Movements.
• Articulators and Facebows.
• Balanced Occlusion and Factors affecting Balanced O.
• Concepts of occlusion (Balanced and Non balanced Occlusion).
• Recording of Occusion for removable prosthodontics.
• Occlusal correction for Removable Prosthesis.
• Occlusion and implant restorations (Loading protocols)
Occlusion
Outline

It is an important factorIt is an important factor
forfor maintaining thethe
stabilitystability of completeof complete
dentures,dentures, with the least
amount of trauma to the

Stomagnathic System
• The movement of the jaw is
orchestrated OR organized by a very
complex set of muscles, which are in
turn controlled by the body's local and
central nervous system
Stoma= mouth
Gnathion = jaws

The
stomatognathic
system= the
masticatory
system =
• Teeth
• Periodontium
• Jaws
• TMJ
• Associated muscles +
tongue & ms of the soft
palate
• Investing tissues
• Neural control

• When opposing teeth are in contact
and mandibular movements are
made, the direction of the
movement is controlled by the
neuromuscular system as limited by
the movement
The stomatognathic systemThe stomatognathic system

Muscles of Mastication:
Neuro Muscular
System:
Masseter
Temporalis
Lateral Pterygoid
Medial Pterygoid
Tempromandibular
Sphenomandibular
Stylomandibular
TMJ Capsule
Associated Ligaments

• The letters TMJ are short
for of 'temporo-mandibular
joint', which is the joint
connecting your lower jaw
and your skull.
The movement in this joint lets you open and
close your mouth and chew from side to side.
Temporalis
Masseter

1.Is the articulation between the mandible and
the cranium .
2.It is a bilateral articulation .

It has 4 anatomical partsIt has 4 anatomical parts::
1- Condyle
2- Articular fossa
3- Articular disc
4- Articular capsule
TMJ: is a bilateral joints permits the mandible
to move as a unit with two functional
patterns:
- Hinge (inferior portion)
- Translation (superior portion)

 Condyle: The rounded
articular surface at the end
of the mandible (lower jaw).
 Glenoid fossa: A deep concavity in the temporal bone at
the root of the zygomatic arch that receives the condyle of
the mandible.
 Tubercle: A slight elevation from the surface of the bone
giving attachment to a muscle or ligament.

Biconcave
articular
disc
C.T. capsule
• Dense fibrous connective tissue
• Lacks blood vessels and nerves
• Able to tolerate forces without damage or pain being produced
• Provides protection to condyle and fossa during movements

The Synovial fluid:Consist of small amounts of a clear,
straw-colored viscous fluid. It is an
infiltrate of the blood diffused out from
the rich capillary network of the
Synovial membrane.
Function:
1- Lubrication
2- Nutrition.
3- Clear the tissue debris.

TMJ LIGAMENTS AND CAPSULE
1-Collateral(discal)
2-Capsular
3-Tempromandibular
4-Sphenomandibular
5-Stylomandibular

Yellow Stylomandibular Ligament
Red Pterygomandibular raphe
Green Sphenomanibular ligament

Muscles of Mastication:
Masseter
Temporalis
Lateral Pterygoid
Medial Pterygoid
Anterior belly of digastric
Mylohyoid muscle
Geniohyiod muscle
Accessory muscles of mastication

 Elevation of mandible (closes the jaw)
to close the mouth, Forceful jaw closing.
MasseterMasseter
Temporalis
 Elevation of the mandible (closes the jaw)
 Assist in Retrusion of mandible
 No activity when mandible is elevated very slowly.
 Assist in protrusion of mandible
• Elevation of the mandible (closes the jaw)
• Minor contribution to protrusion of the mandible
• Right medial pterygoid with left lateral pterygoid turn the chin to left
side
Medial PterygoidMedial Pterygoid
Wikipedia

• Protrusion of the mandibleProtrusion of the mandible:: The primary
function of the lateral pterygoid muscle is to pull the head of
the condyle out of the mandibular fossa along the articular
eminence to protrude the mandible.
• Jaw openingJaw opening (Depresses the mandible(Depresses the mandible))
it is assisted by the digastric, mylohyoid and geniohyoid
muscles..
• SIDE TO SIDESIDE TO SIDE movements GRINDING
MOVEMENT
• Unilateral action of a lateral pterygoid produces contralateral
excursion (a form of mastication), usually performed in concert
Lateral Pterygoid
Wikipedia

In normal chewing
function, the
mandible opens,
and then, while
initiating closing,
there is a shift
slightly to the side
of the bolus, due to
the orientation of
the masseter and
medial pterygoid.

opening the mouth
(depressing the
mandible), with the
assistance of the
Digastric.
The oblique orientation of
the Masseters and Med.
Pterygo. create a sling.
The non-working side
Med. Pterygo. contacts
simultaneously with the
opposite side working
Masseter
normal reciprocal functioning of the Lateral Pterygoids
and Masseters/Med.Pteygoids/Temporalis

The combinded efforts of the Digastrics and
Lateral Pterygoids provide for natural jaw
openingDigastric muscles is not a muscle
of mastication but it play an
important role in mandibular
function

Due to the orientation of the Lateral Pterygoids and
the oblique alignment of the condyles in relation to
each other, contraction of the Lat. Pt. initiates an
instantaneous translation of the condyles. The slope
of the
eminence provides for immediate mandibular
depression and disclusion of the teeth

The Lateral Pterygoid muscles
move the condyles laterally (from
side to side)

The closure of the mandible does not occur in a
straight upward movement but rather in a curve

In the edentulous patients,
use the posterior border
position
At the accepted VD
(Centric occluding relation)

Centric Occlusion made to
coincide with CR

The static relationship between the incising
or masticating surfaces of the maxillary and
mandibular teeth, or tooth analogues.

The contact relationship
between the occlusal
surfaces of teeth during
function.
It is the DYNAMIC contacts relationship
of the teeth as the mandible moved to
and from eccentric relation.

EXCURSIVE MOVEMENT
Movement occurring when mandible
moves away from maximum
intercuspation
OCCLUSAL
INTERFERENCESUndesirable contacts
occurring during
lateral movements

Working side
Non working (balancing)Non working (balancing)
sideside
Side that side of the mandible that moves toward
the median line in a lateral excursion.
The side toward which the mandible
moves in a lateral excursion

The most retruded relation of the
mandible to the maxillae when the
condyles are in the most posterior
unstrained position in the glenoid
fossae from which lateral movement
can be made, (within hinge movement).

The relation of the
mandible to the maxilla
with the mandible in its
most retruded position.
(GPT) 2005(GPT) 2005

A maxillomandibular relationship,
independent of tooth contact, in which
the condyles articulate in the anterior-
superior position against the posterior
slopes of the articular eminences; in this
position, the mandible is restricted to a
purely rotary movements; from this
unstrained, physiologic,
maxillomandibular relationship, the
patient can make vertical, lateral or
protrusive movements, it is a clinically
useful, repeatable reference position
(within functional range of movement).
(GPT 9)(GPT 9)

Dawson has defined this
position as the rearmost,
uppermost, midmost (RUM)
position of the condyle in the
fossa at which the medial
pole of the condyle disc
assembly is braced against
the bony wall of the
eminentia.

Whatever is the definition of centric relation it isWhatever is the definition of centric relation it is
reproducible,reproducible,
The rearmost, uppermost, midmost (RUM)
position of the condyle in the fossa
the most posterior unstrained position in
the glenoid fossae
in the uppermost and rearmost
position in the glenoid fossae
in the anterior-superior position
against the articular eminences

Is the only constant
repeatable position
within the functional
limit to start
constructing a stable
occlusion

MAXIMUMMAXIMUM
INTERCUSPATIONINTERCUSPATION
The complete
intercuspation of
the opposing teeth
independent
of condylar position
GPT8

Maximum Intercuspation:
It is the most closed complete
interdigitation of mandibular and
maxillary teeth irrespective of
condylar centricity.

CENTRICCENTRIC
OCCLUSIONOCCLUSION
The occlusion of opposing teeth when theThe occlusion of opposing teeth when the
mandible is in centric relation,mandible is in centric relation, This may
or may not coincide with the centric
relation in natural dentition GPT 9

Centric occlusion
Static contact relationship that exist
after the jaw movement has stopped
and the tooth contact are identified
Eccentric occlusion
An occlusion other than centric
occlusion
Protrusive occlusion
Lateral occlusion

• In 90% of individuals with full
complement of natural teeth, centric
occlusion (maximum intercuspation),
does not coincide with centric
relation of the jaws.
• In most patients centric occlusion is
located anterior to the centric
relation by 0.5-1.5 mm measured in
the horizontal plane.

Centric occlusion with
teeth present is a tooth
to tooth relation
whereas centric
relation, is a bone to
bone relation
(Static positions)

Teeth fully
intercuspated
with the
condyles in
the RUM
position
The condyle in the
RUM position.
Due to a conflict
between the teeth
and the TMJ, only
one tooth can
touch its
opposing contact
The teeth in conflict
with the optimal
condylar position.
Full intercuspation
of the teeth results
in an eccentric,
occlusally
determined condylar
position.

MP
MO
ICP
RCP
HA
MP = Maximal protrusion
ICP = Intercuspal position
RCP= Retruded Contact
position
HA = Hinge axis
MO = Maximum opening
EE=edge to edge
Posselt’s Figure
Habitual Arc of Closure
EE
MO
All the movements of
the mandible occur
within this envelope,
maximum opening is
reached when the
capsular ligament
prevent further
movement at the
condyle.

VERTICALVERTICAL
DIMENSION OFDIMENSION OF
OCCLUSIONOCCLUSION

VERTICAL
DIMENSION OF OCCLUSION
• The distance measured between two selected anatomic or marked points (usually one on
the tip of the nose and the other one on the chin) when occluding members are in maximal
intercuspation.
GPT 9

VERTICALVERTICAL
DIMENSION OF OCCLUSIONDIMENSION OF OCCLUSION
The degree of separationThe degree of separation
between the maxillae andbetween the maxillae and
the mandible when thethe mandible when the
teeth are in centricteeth are in centric

Inter-alveolar distance
inter-ridge distance
• The vertical
distance between
specified positions
on the maxillary and
mandibular alveolar ridges
at the occlusal vertical

The vertical dimension of the face
when the mandible is in rest
position.
VERTICAL
DIMENSION OF REST

Interocclusal distance
(Free way space)
• The space between the maxillary
and mandibular occlusal surfaces
when the mandible is in the rest
position.
when the mandible is in a specified
relaxed position, it ranges from 2-4 mm.

V D R
V D O
V D R - F W S = V D O
2 to 4 mm.

This relation exists
when the jaws are in
centric relation and
the teeth are in
centric occlusion

Three - dimensional record,
Vertical relation,
Antero - posterior relation
and lateral relation,
i.e. to obtain a centric relation
record it is necessary to
determine the vertical dimension
of occlusion.

In the edentulous
patients, use the
posterior border position
(centric relation) which
is repeatable,
reproducible and within
the functional range of
movements

For this reason, the
relation of the mandible
to the maxilla should
be recorded in the most
retruded position (C.R)
and centric occlusion
made to coincide with
it

In the edentulous patients, use the
posterior border position (c.
relation)

Long centric or Freedom in
centric
The occlusal surface of the teeth could
be altered to allow freedom of tooth
movement in harmony with the rotation
of condyle. (from hinge position to

Anterior Contacts in “old” MI
and CRO after Correction
long centric or Freedom inlong centric or Freedom in
centriccentric

= Balance + Occlusion
• BALANCE = When forces act on a
body in such a way that no
motion results, there is balance
or equilibrium.
• OCCLUSION = Relationship
between the occlusal surface of
the maxillary and mandibular
teeth when they are in contact.

State of equilibrium of
the denture bases in
relation to their
supporting structure
when the opposing teeth
contact.

The simultaneous contacting of the
maxillary and mandibular teeth on the
right and left side and in the posterior
and anterior occlusal areas in centric
and eccentric positions, developed to
limit tipping of the denture bases in
relation to the supporting structures”-
(GPT 5)

• The dynamic
movements of the
teeth in relation to
each other
Articulation:

Stable simultaneous contact of the
opposing upper and lower teeth in
centric relation position with a
continuous smooth bilateral gliding
from this position to any eccentric
position within the normal range of
mandibular function

Balanced
Occlusion/Articulation
• The Bilateral simultaneous
contact of the anterior and
posterior teeth in excursive
movements. (GPT 9)

• There should be no interferences
during movement from centric
position to eccentric positions.
• The movements should be in
harmony with TMJ &
neuromuscular control

Christensen’s phenomenon
• A gap occurring in the natural
dentition or between the opposing
posterior flat occlusal rims when
the mandible is protruded
(posterior open bite). It can lead
to instability in full dentures
unless compensating curves are
incorporated into the dentures.

• But this occlusion could
cause tipping of the denture
in the posterior region.
• Thus simultaneous anterior
& posterior contacts are
required when mandible is
protruded.

Means that when the patient produce a
protrusion with well adapted occlusal rims,
there will be a v- shaped gap between the
rims in the molar region.
Sagittal Christensen phenomenon

Means that when the
patient produce a lateral
excurtion with well
adapted occlusal rims,
there will be a v shaped
gap between the rims in
the molar region on the
balance side. On the
working side there will be
contact between the upper
The Transversal Christensen
phenomenon

Types of posterior
teeth
1- Anatomic teeth
2- Modified or semi-anatomic
tooth
3- Non-anatomic tooth

Denture Occlusion Options
Anatomic
Semi-anatomic
Lingualized
(lingual contact)
Non-anatomic
(balancing ramp)
Non-
anatomic

1- Anatomic teeth1- Anatomic teeth
• Simulate the natural tooth
form.
• It has cusp height of varying
degrees of inclination that
will intercuspate with an
opposing tooth of anatomic
form.
• The standard anatomic tooth
has inclines of approximately
33o

It is measured by
the angle formed
by the
mesiobuccal
cuspal incline to
the horizontal
plan when the
long axis of the
tooth is vertical
to the plane
Cusp Angle

The palatalThe palatal
cusps of thecusps of the
maxillarymaxillary
posterior teethposterior teeth
and the buccaland the buccal
cusps of thecusps of the
SUPPORTING CUSPSSUPPORTING CUSPS
Centric Cusps – ( StampStamp Cusps)
posterior teeth.posterior teeth.

SUPPORTING CUSPSSUPPORTING CUSPS
From a coronal or frontalFrom a coronal or frontal
view, the lingual cuspsview, the lingual cusps
of the upper teeth stampof the upper teeth stamp
into the fossae of theinto the fossae of the
lower teeth and thelower teeth and the
buccal cusps of thebuccal cusps of the
lower teeth stamp intolower teeth stamp into

Non-Centric CuspsNon-Centric Cusps
The buccal cusps of
the maxillary
posterior teeth and
the lingual cusps of
the mandibular
posterior teeth.Help to determine the path of the
supporting cusps during lateral and
protrusive movements.
Non-centric Cusps – (Guiding Cusps)

Problems with anatomic
teeth
1- The presence of cusp
inclines can cause trauma,
discomfort and instability
to the bases because of
the horizontal component
of force that produced
during function.

2- The use of adjustable articulator
is mandatory
3- Various eccentric records must
be made for articulator
adjustments4- Harmonious balanced
occlusion is lost when
settling occurs5- The bases need prompt and
frequent relining to keep the
occlusion stable and
balanced.

6- Mesiodistal interlocking
will not permit settling of
the base without horizontal
force developing. That
acting on thin delicate
mucosa and the underlying
bone creates shearing that
are not well tolerated

Sharp cusped teeth exert less vertical
force for penetration but produce
more lateral force owing to the
inclined plane effect (horizontal
component of force). Flat
teeth exert more vertical force but
produce less lateral force
components

The arrows indicate the
direction and the magnitude of
the force generated by the two
types of teeth as they
penetrate the bolus of food
during masticatory cycle

Problems with
non-anatomic tooth
1- Do not function efficiently unless
the occlusal surface provides
cutting ridges and spillways
2- They can2- They can not be correctednot be corrected byby
occlusal grinding without impairingocclusal grinding without impairing
their efficiency.their efficiency.
3- Appear dull and unnatural.

Selection of toothSelection of tooth
formsforms
is based onis based on
1- The capacity of the
ridges
2- Interridge distance
3- The ridge relationship

4. Esthetics.

5. Patient's age and
neuromuscular coor-
dination.

6. Previous denture-
wearing experience.

Strong well-formed
resist horizontal force
1- The capacity of the ridges

A large interridge distance
creates a long lever arm
through which horizontal
forces created by the inclines
of cusps can act.
Therefore, this force can be
controlled by using flat teeth
as the interridge distance
increases.
2- Interridge distance

Non-anatomic posteriorNon-anatomic posterior
teeth used effectively to control
the forces of occlusion and to
stabilize the denture base supported
by compromised weak ridge in
either class II or class III
ridge relationship
3- The ridge relationship3- The ridge relationship

Classification of Relationship
Between Arches
•Skeletal
•Dental
•Posterior teeth
•Anterior teeth
•General rules
•Class 1 – mandibular only slightly back
•Class 2 – mandibular more backwards
•Class 3 – mandibular more forward

Arrows are where
they should be.
Has ideal overjet
and overbite.
Adult Class I
(Lateral view)

Arrows should be
aligned
opposite to each
other.
Class II -
retrognathic
malocclusion

If you don’t
feel shame,
then do as u
wish

• The natural Teeth are retained
by periodontal tissues, which are
uniquely innervated and structured.
When the natural teeth are lost, not
only the occlusion is lost but also
the attachments.
• In complete artificial
occlusion, all the teeth are on
two bases seated on slippery
Differences between natural andDifferences between natural and
artificial occlusionartificial occlusion
Regarding retention and
stability

In the natural teeth, proprioception
gives guidance to the neuromuscular
control during function.

With artificial occlusion, no such
signal system is present, and the
mandible returns at the end of the
chewing stroke to its optimum
power position which, is centric
relation. If cusps interfere or if
there are premature occlusal
contacts, the bases shift to
accommodate them.

 The natural teeth move
independently and can
immigrate slowly to
unfavorable occluding
positions.
• The artificial teeth move as a unit and
are instantly displaced by dislodging
forces.
Regarding retention and
stability

In Natural Occlusion In Artificial Occlusion
Tooth contact on one side ofTooth contact on one side of
the arch does not directlythe arch does not directly
affect retention and stabilityaffect retention and stability
of teeth on the other side ofof teeth on the other side of
the arch as each tooth isthe arch as each tooth is
anchored independently toanchored independently to
its bony alveolus.its bony alveolus.
Tooth contact on one
side of the arch affects
retention and stability of
teeth on the other side
of the arch as each
artificial teeth are
attached to the same
denture base that rests
on compressible
mucosa.

Incising in the
anterior region
of natural teeth
does not affect
the
posterior teeth but it does so in artificial dentitions.
Regarding eccentric
balance
Differences between natural and
artificial occlusion

*DifferencesDifferences
betweenbetween condylar
and Incisal Angles
are usually wellare usually well
tolerated.tolerated.
*Incisal angle shouldshould
be less or equal tobe less or equal to
condylar angle toto
avoid interference ofavoid interference of
teeth duringteeth during
mandibularmandibular
excursions.excursions.
In Natural Occlusion In Artificial Occlusion

In natural teeth, there is rarely,
bilateral balance during
nonfunctional excursions,
whereas in artificial teeth, it
is necessary to stabilize the
bases.
Regarding bilateral
balance

** Bilateral balance
Rarely found inRarely found in
natural dentition. Ifnatural dentition. If
present, it ispresent, it is
consideredconsidered
balancing sidebalancing side
interference.interference.
* It is generally* It is generally
considered forconsidered for
base stability.base stability.
In Natural
Occlusion
In Artificial Occlusion

Bilateral balance in artificial teeth, is
necessary to stabilize the bases.

7. Horizontal thrusts on
one side of the
natural teeth during
mastication affect
only the side involved
and are well
tolerated, whereas,
• In artificial Teeth, the effect is bilateral and
usually traumatic in nature.
Regarding bilateral
balance

. A malocclusion of natural
teeth may be uneventful for
several years and if
symptoms do occur, they are
usually localized to the
involved tooth or teeth.
• A malocclusion of
artificial Teeth creates an
immediate response and
usually involves a large area
of the supporting tissues.
Regarding bilateral
balance

8. Mastication in the
second molar region in
the artificial occlusion
shifts the base if it is on
an inclined foundation,
• whereas, in natural
teeth, it is one of the
power points of
mastication.

Dentists can restore theDentists can restore the
natural tooth formnatural tooth form
artificially but not it’sartificially but not it’s
attachmentsattachments
• The above differences make it
necessary to consider artificial
occlusion as a different problem
with different requirements if it
is to serve efficiently with the
least amount of trauma to the
supporting tissues.

01 occlusion in prosthodontics introduction - stomatognathic system- definitions

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