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, at any
given degree of jaw separation
(within hinge movement = within the normal
range of mandibular function )
CENTRIC OCCLUSION
The occlusion of opposing teeth when the mandible is in centric relation.
May or may not coincide with MI.
Centric occlusion with
teeth present is a
tooth to tooth relation
whereas centric
relation, is a bone to
bone relation
(Static positions)
MAXIMUM INTERCUSPATION
The complete intercuspation of the opposing teeth independent
of condylar position.
Maximum
Intercuspation:
It is the most closed
complete interdigitation
of mandibular and
maxillary teeth
irrespective of condylar
centricity.
• The distance measured between two points when occluding members are in contact in centric occlusion.
VERTICAL
DIMENSION OF OCCLUSION
.
Balanced Occlusion is important to:
Condylar guidance
Incisal guidance
Occlusal Plane
Cusp Height
Compensating curve
uidance
1- Condylar inclination
The inclination of the condylar paths varies in
different individuals and from side to side in
the same person. It depends upon
The condylar guidance:
movements
2-The incisal guidance
The
2-The incisal angle
HO
The incisal inclination is
called the incisal guide
angle and the influence
that this angle has on
mandibular movements is
termed incisal guidance.
The incisal guide angle
by increasing the
horizontal overlap (HO)
It can also be made less steep
by reducing VO
B
A- The Esthetic Factors Dictated A Steep Vertical
Overlap With Little Horizontal Overlap. Therefore
Steeper Posterior Cuspal Inclines Had To Be selected
B- In eccentric movements the inclinations of the
posterior cusps are sufficient to prevent anterior
interference.
Anterior interference
I.G. GREATER THAN C.G
X
• 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.
effect an occlusal balance.
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
Condylar guidance
Incisal guidance
Occlusal Plane
Cusp Height
Compensating curve
• I.G.
esthetics and phonetics requirements.
but in no case should I.G. exceed
that of the C.G.
effect an occlusal balance.
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
1- The condylar guidance.
2- Prominence of the
compensating curve.
3- The inclination of plane
of occlusion
4- Height of the cusp (cusp
angle)
5- The incisal guidance
O. P. is an imaginary
plane 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)
Condylar guidance
Incisal guidance
Occlusal Plane
Cusp Height
Compensating curve
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
* The incisal guidance and inclination of the plane of
occlusion: can be altered within a small range according
to esthetic and physiologic (phonetic) factors.
3- The Plane 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- 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
The occlusal plane is
parallel to the ear nose
plane (ala tragus line)
The occlusal plane
is parallel to the
interpupillary line
Anterior and Posterior 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
Determination of the occlusal plane
• The Height Of Occlusal Plane
Should Be 1-2 Mm. Below The
Upper Lip.
Anteriorly Is Influenced By:
• The Length Of The Lip,
• Ridge Fullness,
• Ridge Height, The Amount
Of The Maxillomandibular
Space And
• The Incisal Guide Angle.
Aesthetic base.
Chewing
• The tongue works in coordination
with the buccinator muscle to keep
the food on the occlusal surface of the
teeth. When the teeth meet during
the chewing cycle, they mash the
food. The food is pushed away from
the occlusal table to the cheek and
tongue side. Then the tongue and
cheek put the food again on the
occlusal surface of the teeth and
another masticatory cycle starts.
Functional base (chewing and speech)
Chewing
• The height of occlusal plane
should be 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 occlusal surface of the teeth should be below the
greatest convexity of the tongue.
• This also improves the stability of lower denture.
Functional base (chewing and speech)
Speech: • During speech, the tongue pushes
against the sides of the teeth to produce a seal for better pronunciation of words.
Functional base (chewing and speech)
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
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
The compensating curve of the artificial occlusion
corresponds to a combination of these
curves in natural teeth. It is considered one of the more 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 (cuspal inclines of tooth
and 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.
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
Types of posterior teeth
1- Anatomic teeth
2- Modified or semianatomic
tooth
3- Non-anatomic tooth
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
Non-
anatomic
tooth
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
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
Sharp cusped teeth need
less vertical force for
penetration but produce
more lateral force owing to
the inclined plane effect.
Flat teeth more vertical
force but produce less
lateral force components
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
Strong well-formed resist
horizontal force
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
A large 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
1) Lever balance
2) Occlusal balance
"Balanced Occlusion"
1- Lever balance
Dependent on tooth
position as related to
its base
Lever balance the greater
the stability of the base.
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 or slightly lingual to it.
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.
2- Occlusal balance
"Balanced Occlusion"
1) Unilateral occlusal balance
2) Bilateral occlusal balance
3) Protrusive occlusal balance
C. Unbalanced occ.
B-Balanced articulation the mandible moves
essentially forward and the
occlusal contacts are smooth
and simultaneous in the
posterior both on right and left
sides and on the anterior
teeth.
A. Centric occlusion
2- Occlusal balance
"Balanced Occlusion"
Is dependent on tooth contact
"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".
2- Occlusal balance
"Balanced Occlusion"
Bilateral balance in artificial teeth, is
necessary to stabilize the bases.
The objective of occlusal
balance is to create bilateral
contacts from the centric
position to all eccentric
position, that are free from interference, smooth,
uniform and in harmony
with movement of the
mandible
They modify the effect of
the plane of occlusion
and the compensating
curve, and considered an
important factor in
denture stability
The cuspal inclines
for posterior teeth
depend on the plane
of occlusion
selected by the
dentist
if steep vertical overlap
and low posterior tooth
inclines are used, a
spaced horizontal
overlap of the anterior
teeth must be selected
If a flat or nearly horizontal
incisal guidance angle is
chosen, shallow posterior
tooth inclines should be
selected, particularly if the
condylar guidance also is
shallow
In edentulous patients the
incisal guidance angle is
determined by the dentist,
therefore the posterior tooth
inclines are chosen at the time
the horizontal overlap of the
anterior teeth is set
Two figures with the same condylar inclination but
different incisal guide inclinations. A, Steep vertical
overlap, with resultant steep cusp inclines. B, Less
incisal angle, with resultant flatter cusp inclines
The influence of incisal and
condylar guides on steepness of
cusps in protrusive relations
All five factors of balance interact with each other, and changes in any one effect changes in the others. for the final analysis, 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)
factors.
* Cusps, on the teeth and tooth inclination of cuspless
teeth and compensating curve: are the real working
tools of balanced occlusion.
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 tothis way
With the articulator programmed
for the condylar inclination and
the upper and lower anterior
teeth set for a flat incisal
guidance, only the posterior teeth
need be considered for their
position to establish a balanced
occlusion
Condylar guidance
Incisal guidance
Occlusal Plane
Cusp Height
Compensating curve
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