Occlusion in prosthodontics (Revision for 5th year students)

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 Occlusion for removable prosthodontics.
• Occlusal correction for Removable Prosthesis.
• Occlusion and implant restorations (Loading protocols)
Occlusion Outline

•Maintaining the stability of
complete dentures.
•Esthetic and function.
•Preservation of the remaining
structure.

It is an important factor for
maintaining the stability of
complete dentures, with the
least amount of trauma to the
supporting tissues.

Is the property of the dentures,
which causes them to resist
displacement during function
and parafunction. It is chiefly
affected by the various
occlusions of the teeth

Is the Resistance of Denture to
Tipping (Rocking, torsional forces)
during function

When you
lose, don't
lose the
lesson

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 system

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

 Elevation of mandible (closes the jaw)
to close the mouth, Forceful jaw closing.
Masseter
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 Pterygoid
Wikipedia

• Protrusion 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 opening (Depresses the mandible) it is
assisted by the digastric, mylohyoid and geniohyoid
muscles..
• SIDE TO SIDE movements GRINDING MOVEMENT
• Unilateral action of a lateral pterygoid produces contralateral
excursion (a form of mastication), usually performed in
concert with the medial pterygoids.
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.

The Lat. Pterygo. advance the
condyles, thereby 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 combined efforts of the Digastrics and Lateral
Pterygoids provide for natural jaw opening
Digastric 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

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.

Working side
Non working (balancing) side
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

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

A common plane established by the incisal
edges and occlusal surfaces of the teeth.
• Aesthetic base.
• Functional base.
• Mechanical base.
Determination of the occlusal plane
[This is usually curved and is therefore not strictly a plane]

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

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)

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 is reproducible,
stable and functional position.
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

Whatever is the definition
of centric relation it is
reproducible, repeatable
stable and functional
position.

MAXIMUM
INTERCUSPATION
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.

CENTRIC
OCCLUSION
The occlusion of opposing teeth when the
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)

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.

MP
MO
ICPRCP
H A
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

VERTICAL DIMENSION OF
OCCLUSION

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

VERTICAL
DIMENSION OF OCCLUSION
The degree of separation
between the maxillae and
the mandible when the teeth
are in centric occlusion.

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

The vertical dimension of the face when
the mandible is in rest (balanced)
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.

VALUE OF VERTICAL DIMENSION
Biological importance of correct registration of
the occlusal vertical dimension; the patient can:
1 - Masticate his food efficiently.
2 - Speak without impediment.
3 - Present a normal facial appearance.
4 - Experience a minimum amount of
discomfort in using his dentures.

1- Inharmonious facial proportions (Appearance).
2- Flexor muscles are in constant strain.
3- The lips are unnaturally separated and have a
strained appearance.
4- The free-way space will be obliterated, inability
to find comfortable resting position.
5- Clicking of teeth may occur during speech and
mastication.
Sequel Of Improper Registration Of V.D.0.
A . High Vertical Dimension Of Occlusion:

Sequel Of Improper Registration Of V.D.0.
6- Generalized soreness of the residual ridge.
7. Difficulty in swallowing and gagging
sensation (Discomfort).
8. Loss of biting power and muscular fatigue.
9. Interference with speech .
10. Pain under the basal seat and trauma to
the supporting structures .
11. Accelerate bone resorption.
A . High Vertical Dimension Of Occlusion:

High Vertical Dimension
Generalized
inflammation
Flabby Tissue
Obliterated
free-way space
High Plane of Occlusion

• Angular cheilitis
• Esthetic
complaints:
•Chin prominent
•Poor lip support
(Insufficient OVD)
Establishing too little V.D.

Cheek Biting
Angular Cheilitis

• Indefinite pain location resembles
neuralgia of cheek
• Lack of chewing power
• Minimal ridge discomfort
• Costen’s syndrome mild deafness,
tenderness in TMJ, burning sensation of
the tongue, throat and nose, dryness of
the mouth.
Insufficient OVD

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

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 habitual intercuspal position).

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

= 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.

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 and the lower rims.
The Transversal Christensen
phenomenon

• 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 tissues.
Differences between natural and
artificial 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 of
the arch does not directly
affect retention and stability
of teeth on the other side of
the arch as each tooth is
anchored independently to
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

*Differences between
condylar and Incisal
Angles are usually
well tolerated.
*Incisal angle should be
less or equal to condylar
angle to avoid
interference of teeth
during mandibular
excursions.

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 in natural
dentition. If present, it
is considered balancing
side interference.
* It is generally
considered for base
stability.

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.

. 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.

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 the
natural tooth form artificially
but not it’s attachments
• 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.

Difference between Natural and Artificial Occlusion
Natural teeth Artificial teeth
Periodontal ligament support No Periodontal ligament
Function independently Function as group
Mal occlusion not problematic over year Mal occlusion causes drastic problem
Non vertical forces well tolerated Non vertical forces are damaging to
supporting tissues
Incising doesn’t affect posterior teeth Incising affects all teeth on the base
Second molar is favored position for
mastication
Heavy pressure of mastication in second
molar region; tilt base and shifts it on
inclined surface.
Bilateral balance is rarely found and if
present considered as interference.
Bilateral balance is necessary for base
stability
Proprioceptive impulses give feed back to
avoid prematurities and interferences . So
a habitual occlusion away from centric is
established.
No feed back Proprioceptive impulses
and denture base rest in centric relation.
Any prematurities in this position will
shift the denture base.

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 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

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 adjustments
4- Harmonious balanced occlusion
is lost when settling occurs
5- 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 can not be corrected by occlusal
grinding without impairing their
efficiency.
3- Appear dull and unnatural.

Selection of tooth forms
is 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 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 relationship

Balanced
Occlusion/Articulation

1- Provide maximum denture stability during functional
and parafunctional movements of the mandible
2- Help in distribution of the masticatory pressure
over the supporting tissues and reduce trauma to the
underlying tissues
3- Increased efficiency of mastication
4- Psychologically it is more comfortable to the
patients who enjoy comfort and satisfaction only
when eccentric balance is present

Balanced Occlusion is important to:
Prevent the denture movement during
chewing, produce efficient mastication
and in turn help in stabilizing the denture

Types of Balance as Related
to Complete Denture
1) Lever balance
2) Occlusal balance

1- Lever balance
Dependent on
tooth position as
related to its base

The greater the Lever balance and
the greater the stability of the base
1. The larger ridge.
2. The closer the teeth to ridge.
3. The more lingualized occlusion.
4. The more centered the force of
occlusion anteroposteriorly.
To achieve the lever balance

The better the Lever
balance the greater
the stability of the
denture base during
mastication until
teeth contact.
1- Favorable tooth- to -ridge crest position
Inter bolus exit balance is
compensated by lever balance
To achieve the lever balance

a- The height of occlusal plane should be
1-2 mm. below the lip line.
Aesthetic base.
Leverage action
Functional base
2- Determination of the height
of the occlusal plane

b- The occlusal surface of the teeth should be
below the greatest convexity of the tongue.
This also improves the stability of lower denture.

convenient and at
a level familiar to
the tongue to
perform its action
easily and stop
food escaping to
the floor of the
mouth.
The height of occlusal plane should be

C- Leverage action: The nearer the
occlusal plane to the basal bone of
the jaws, the less the leverage
action and the better the stability.

Unilateral lever balance
Equilibrium of the base on its
supporting structures when a
bolus of food is interposed
between the teeth on one side
and a space exist between the
teeth on the opposite side

1. Placing the teeth over the ridge.
2. Denture base area covers as
wide area on the ridge as
possible.
3. Placing the teeth as close to the
ridge as other factors will permit.
4. Using as narrow a buccolingual
width occlusal food table.
To achieve the unilateral lever balance

2- Occlusal balance
Is dependent on
tooth contact

2- Occlusal balance
1) Unilateral occlusal balance
(Group function) This is not followed for balanced
occlusion of complete denture It is more pertained
to fixed partial dentures
2) Bilateral occlusal balance
3) Protrusive occlusal balance
4) Mutually protected occlusion
(Canine protected) This is not followed for
complete denture

The group function concept
.
It requires teeth on the
working side to be in
contact in lateral
excursion simultaneously
with a smooth,
uninterrupted glide
and teeth on the non-
working side are free of
any contact.
1- Unilateral occlusal balance
This is not followed during
complete denture
construction. It is more
pertained to fixed partial d.

Bilateral simultaneous occlusal contact
of teeth, anteriorly and posteriorly, in
both centric and eccentric positions.
Gliding of the teeth across each other
during their movement from one position
to another, without any interferences.
2- Bilateral occlusal balance

Bilateral balance in artificial teeth, is
necessary to stabilize the bases.
Centric occlusion
Balanced
eccentric
occlusion

3- Protrusive occlusal balance
 There should be at least 3
points of contact on the
occlusal plane Two located
posteriorly and one anteriorly.
 The more the number of
contacts the better will be
the balance.
 Absent in natural dentition.

4- Mutually Protected Occlusion
• Also called canine protected occlusion
• Anterior teeth overlap prevents the posterior teeth
from making any contact on either the working or
the nonworking sides during mandibular
excursions.
• Anterior teeth bear all the load and the posterior
teeth are dis-occluded during excursions. Protecting
the posterior teeth
• In CO, posterior teeth direct forces through their
long axis and anterior teeth are slightly in or out of
contact. Protecting the anterior teeth.

When the patient moves to the side during chewing,
there are only one or two tooth contacts, and then the
denture bases will tip up and be very difficult to control.
If they do not tip because the ridges and/or the patient’s
muscle control prevent this, they will create pain,
discomfort, and ulceration.

1. The condylar guidance
2. The incisal guidance
3. The inclination of plane
of occlusion
4. The compensating curve
and
5. Cusp angle of teeth (Cuspal
inclination)

Anterior
determinants of
occlusion
Posterior determinants
of occlusion
The determinants of occlusion

The angle formed by the steepness of the
articulator surface of the Temporal bone as
related to a horizontal plane
The condylar guidance is the only factor
given by the patient
1- Condylar inclination

Condylar Guidance Angle
The angle formed by an
imaginary horizontal line
at the superior head of
the condyle and the path
that the condyle will
pass through during
function
Varies from individual to
individual because of
anatomical differences

1. The shape of the glenoid
fossa.
2. The variation of the
thickness of the articular
disc in its different parts.
3. The relation of the
condyle to the disc during
movement.
4. The extent of mandibular
protrusion
The inclination of the condylar paths varies in
different individuals and from side to side in
the same person. It depends upon

Bennett Angle
The angle formed by the
sagittal plane (assumed
straight protrusive path)
and the path of the
advancing (orbiting)
condyle during lateral
mandibular movements
as viewed in the
horizontal plane.
Balancing side. Working side.

• Working side: (Mandible moving toward
the cheek)
• Balancing side: (Mandible moving
toward the tongue)
• Working side condyle pivots within the
socket and is better supported.
• Balancing side condyle has a downward
orbiting path. It is traveling a greater
distance in ‘space’ and is more prone to
injury or damage.

 Ease of determination
 Used to set condylar
guidance
 Helps setting teeth
for best occlusal
contacts
Protrusive Records
To Set Condylar Inclination

Adjust Protrusive Guide for
Maximal Interdigitation

After protrusive record
making the same procedure is
followed, however the patient
is asked to move his mandible
to left and right and getting
Right and left lateral relation
him to bite on wax wafer, two records are made, one
for left and one for right. These records are used to
adjust the lateral condylar inclination.

In Hauau model
H articulator
Hanau equation
can be used
L = H/ 8+ I2

It is the path taken by the
lower anterior teeth as it move
in protrusive movements
against the palatal surface of
upper anteriors till become
edge to edge.
2-The incisal guidance
It’s the influence of the contacting surfaces
of the mandibular & maxillary anterior teeth
on mandibular movement

Relation
between the
incisal path of
patient and
incisal
guidance of
articulator

Incisal Guidance Angle
The angle formed by the
intersection of the plane of
occlusion and a line within
the sagittal plane
determined by the incisal
edges of the maxillary and
mandibular central incisors
when the teeth are in
maximum intercuspation
HO

The incisal inclination is
called the incisal guide
angle and the influence that
this angle has on mandibular
movements is termed
incisal guidance.

Incisal Guidance Angle
This angle varies directly with the
vertical overbite and inversely with
the horizontal overjet
This angle is set to 10˚ in CD and
not exceeding 20˚

↓ Incisal Guidance Angle
by either:
↑ Horizontal overlap
↓ Vertical overlap
Incisal Guidance

The incisal guide angle can be controlled when
developing a balanced occlusion. With a given amount of
vertical overlap (VO) the incisal guide angle can be made
flatter by increasing the horizontal overlap (HO)

It can also be made less steep by reducing VO
A- Steep incisal guidance
B. Medium incisal guidance
C. Zero incisal guidance
B

•I.G. can be set by the dentist
according to esthetics and
phonetics requirements.
but in no case should
I.G. exceed that
of the C.G.

• Steep I.G. calls for steep cusps,
steep O.P. or a steep C.C. to effect an
occlusal balance.
• This type of occlusion is detrimental
to the stability and equilibrium of the
denture base.
Steep I.G. results in harmful inclined
planes with their harmful risk to the
supporting tissues

O. P. is formed by
lines connecting
tips of incisor
teeth and
distobuccal cusps
of the most
posterior teeth on
each side of arch
3- The Plane of Occlusion
(Plane of Orientations)

The occlusal plane is
parallel to the ear
nose plane
The occlusal plane is
parallel to the
interpupillary line

1- Aesthetic base
2- Functional base (chewing and speech)
3- Physical and mechanical (leverage
action and parallelism).
Factors must be considered:
Determination of the occlusal plane

O.P. At (a) is the ala-
tragus plane obtained
from the patient. At
(b) is a compromise
plane midway
between ridges. At (c)
is a low plane
necessary to favor
weak lower ridges

•The orientation of the occlusal plane
becomes a fixed factor of occlusion
•Any necessary alteration for balancing
the occlusion must therefore be made
on other factors affecting the occlusion
(that is, the cuspal inclination or the
prominence of the compensating curve)

1- Spee’s curve
The anatomic curvature of the occlusal alignment of the
lower teeth beginning at the tip of the lower cuspid and
following the buccal cusps of the natural bicuspids and
molars continuing to the anterior border of the ramus
4- Compensating curves

The buccal cusps of the
lower posterior teeth are
slightly higher than the
lingual cusps, and a line
drawn through the buccal
and lingual cusps of the
teeth on the other side
forms a lateral curve
called the curve of Wilson
2- Wilson’s curve

A proposed ideal curve of occlusion..
the curve of occlusion in which each cusp and
incisal edge of upper and lower teeth of right and
left sides touches or conforms to a segment of the
surface of a sphere eight inches in diameter its
center in the region of the Glabella
3- Monson’s curve

Curve of Monson:
• It is a combination of curve of
Spee and the curve of Wilson.
• Coronal and sagittal planes.
• Concave for the mandibular
arch and convex for the
maxillary arch.
• in centric occlusion form a
segment of a sphere of 4 inches
radius with the center of the
sphere at the glabella

The compensating curve of the
artificial occlusion corresponds
to a combination of these curves
in natural teeth.
It is considered one of the most
important factors in establishing
balanced occlusion

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
4- Cusp Height (inclination of cuspless
teeth)

A steep condylar guidance necessitates teeth with steep cusps.
Cusp height is therefore an important determinant as it modifies
the effect of occlusal plane and compensating curves.

• Steep I.G. calls for steep cusps, steep O.P. or a
steep C.C. to effect an occlusal balance. The
angle of this movement is governed by the
cusp angles and hence the lower incisors will
move at the same angle as the lower molars

Condylar
guidance
Incisal
guidance
Occlusal
Plane
Cusp
Height
Compensating
curve
Theilmann’s Formula
The five factors of balanced occlusion related
to one another on a balance beam. To keep the
occlusion in balance is a simple procedure
once the factors are related to this way

Condylar
guidance
Incisal
guidance
Occlusal
Plane
Cusp
Height
Compensating
curve
Theilmann’s Formula
* The incisal guidance and inclination of the plane of
occlusion: can be altered within a small range according
to esthetic and phonetic and anatomical factors.

The dentist can only control four
of five factors
* The condylar guidance: can be completely fixed
and is not his to change.
* The incisal guidance and inclination of the plane of
occlusion: can be altered within a small range
according to esthetic and physiologic
(phonetic)and anatomical factors.
* Cusps on the teeth and tooth inclination of
cuspless teeth and compensating curve: are the
real working tools of balanced occlusion.

• Steep I.G. calls for steep cusps,
steep O.P. or a steep C.C. to effect an
occlusal balance.
• This type of occlusion is detrimental
to the stability and equilibrium of the
denture base.
Steep I.G. results in harmful inclined
planes with their harmful risk to the
supporting tissues
According To The Formula

• To achieve balanced occlusion: For
high condylar guidance we need to
have high compensating curve,
occlusal plane and cuspal height.
• To achieve balanced occlusion: For
high incisal guidance we need to have
high compensating curve, occlusal
plane and cuspal height.
According To The Formula

I- Concepts Of Occlusion In Centric
Position.
a. Concepts of balanced occlusion
II- Concepts Of Occlusion In
Eccentric Position:
b. Concepts of non-balanced occ.

I-Concepts of Occlusion in
Centric Position
1- Point centric.
2- Long centric.

1- Point centric
Anatomic teeth set in tight interdigitated centric
occlusion with an incisal overlap for esthetics
I-Concepts of Occlusion in Centric Position

The point centric concept is that in
which centric occlusion coincide
with centric relation, such occlusion
is neither stable nor physiologic.
Both function and stability of
complete dentures are well served
by the freedom in centric concept
1- Point centric

Once CR is established, CO can
be built to coincide with it
providing a broad flat area of
tooth contact in this position
(a so called "freedom in centric")
2- Freedom of centric
(Long centric)

• The continuous line denote maximal intercuspal position,
the shaded line denotes the positioned centric relation.

2- Freedom of centric
(Long centric)
This flat area, having a
length of 0.5-1mm,
gives the mandible
freedom to close in
Centric or slightly
anterior to it without
any interference.

In Long Centric, the patient
is given the opportunity to
move on a horizontal plane
from centric relation to
centric occlusion
without any changes in
vertical dimension

When cuspless teeth are used this freedom exists
automatically.
In both situations the anterior teeth are arranged to
allow this freedom of movement i.e. the anterior teeth
are not arranged in contact when the jaws are in
centric relation.

The coincidence of Centric Occlusion & Centric Relation (CO = CR),
when there is freedom for the mandible to move slightly forwards
from that occlusion in the same sagittal and horizontal plane
(Freedom in Centric Occlusion).
“LONG” CENTRIC No Anterior Contacts

Balanced occlusion in eccentric position is
usually associated with cusp form
posterior teeth, with the exception of
organic occlusion, that employs cusp
form posterior teeth that are not arranged
to provide protrusive and bilateral balance
A-Concepts of Balanced Occlusion in
Eccentric Position

Spherical concept of occlusion
Positioning artificial anatomic posterior teeth
to simulate natural occlusion. The teeth, must
be arranged with a compensating curve
running anteroposteriorly and mediolaterally

Spherical concept of occlusion
Teeth make contact in lateral excursion
on the working and balancing sides

Bilateral Balanced Denture Occlusion with
Anatomic Posterior Denture Teeth

Balance with non-anatomic teeth
1. Placing "balancing ramps" behind the
lower second molars.
2. Tilting the second molars to create an
inclined plane.
3. Arranging teeth in a compensating
curves.

Zero Degree Teeth with
Balancing Ramp
Setting up the
teeth in a flat
plane and utilize
a balancing ramp
just distal to the
second molar.

Monoplane with Balancing Ramps

Balanced occlusion Vs Non-Balanced Occ.

Non- Balanced Occlusion
Concepts in Eccentric
Positions

Monoplane Occlusion
•Advantages of monoplane occlusion:
(Non-Anatomic Occlusion)
• Non-Balanced. Does not require
precision with records.
• By removing any inclines, destructive
forces on residual ridges is reduced.
• Easier to adjust.
• Freedom in CR

Position the posterior mandibular
teeth over the crest of the ridge.
they are set to a flat plane and Since
there is no vertical overlap of the
anterior teeth all of the mandibular
teeth are on the plane of occlusion.

Monoplane Occlusion
The posterior limit of the lower posterior teeth is the point
at which the mandibular ridge begins to curve upward,
with elimination of contact between the upper and
lower second molars.

For Crossbite patients, this concept
is more adaptable to class two and
class three malocclusions.

Monoplane Occlusion
•The patients should avoid incising
with their anterior teeth,
X

The steeper the condylar inclination the
greater the posterior discrepancy in
excursion and the greater the need for
balancing ramps, and so in this patient,
balancing ramps were added to improve the
stability of the lower denture.
balancing ramp

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