The most retruded relation of the · 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

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