basics of complete denture occlusion

04/08/23 Dr Mohammed M Fuad 1

الرحمن الله الرحمن بسم الله بسمالرحيمالرحيم


BASICS OF COMPLETE BASICS OF COMPLETE DENTURE OCCLUSION DENTURE OCCLUSION


DEFINITIONSDEFINITIONS


Occlusion“The static relationship between the

incising or masticating surfaces of the maxillary and mandibular teeth when they are in contact in either centric or eccentric jaw relation.”

“Static tooth contact”


Centric occlusion • It is the maximum intercuspation

between upper and lower teeth (cusp to fossa relation)

• It is a tooth‑to‑tooth relation.

• In complete dentures, ideally, CR=CO.


Articulation

“The contacting of teeth as the mandible moved to and from centric and eccentric relation (dynamic)”.

“Dynamic tooth contact”


Centric relation • Most posterior retruded unstrained

position of mandible in relation to maxilla at established vertical dimension from which any eccentric movement can be done at a given degree of jaw separation.

• Called horizontal jaw relation. • It is bone to bone relation.


Eccentric occlusion • “It is the occlusion of opposing

teeth when the mandible is in any other relation than centric relation”.

• The contacting of teeth on eccentric occlusion can occur with the jaws in a static relation .


Gliding occlusion

• “ It is the contacting of teeth in motion”.

• It occurs when the occlusal surfaces of the teeth make contact when the mandible is moving to and from eccentric and centric jaw relations.


Basic mandibular Basic mandibular movements. movements.

1) Hinge axis movement2) "Translation" • The max opening in hinge

movement=25 mm (measured from incisal edges).

• The average opening of hinge and translation together is in the area of 50mm.

• The three main categories of mandibular positions:

1. MI2. CR3. Eccentric positions or movements• Condylar guidance refers to

angulations and curvature of the bony structures of TMJ (fixed ).


What happens if you have a greater degree of condylar guidance? Lesser?

• The greater/lesser degree of posterior tooth disocclusion


What happens with an overbite?

• That is a greater

vertical overlap,

therefore the

greater the amount

of disengagement


What happens with a greater horizontal overlap (overjet)?

• The further the lower

incisors will have to

travel before contacting

the lingual surfaces of

the upper incisors

• A later and lesser

disocclusion of the

posterior teeth.


What is vertical dimension?

1) the height of the

lower third of the

face

2) 2) the distance

between the upper

and the lower

arches.


what are the types of vertical dimension?

1)Vertical dimension of Occlusion: Distance between maxilla and mandible when teeth are in MI

2)Vertical Dimension at Rest: Distance between the maxilla and mandible when in physiological rest position.


What is physiological rest position?

• PR represents the normally relaxed state of the lower jaw. It hangs open 2-3 mm.

• Force of gravity is equal to the neuromascular tonality of muscles of mastication


What is "Freeway space"?

• That is the difference in distance between VDO and VDR

2-4 mm


What is Canine guidance?

• The canines will guide the lateral protrusive movement and DISOCCLUDE all other teeth and guide the teeth back into occlusion


Differences between natural and artificial

occlusion


Natural occlusionNatural occlusion Artificial occlusionArtificial occlusion

1.1. Periodontal Periodontal tissuestissues

• The teeth are retained by periodontal tissues.

• All the teeth are on bases seated on slippery tissues

2.2. MalocclusionMalocclusion • May be uneventful. • Evokes an immediate response and involves all of the teeth and the base.

3.3. Nonvertical forcesNonvertical forces • Affect only the teeth involved • and are usually well tolerated,

• The effect involves all of the teeth on the base. It is usually traumatic to the supporting structures.

4.4. IncisingIncising • Does not affect the posterior teeth. • Affects all of the teeth on the base.

5.5. The favored area The favored area for masticating for masticating hard foods.hard foods.

• The second molar region. • Heavy pressures of mastication in the second molar region with artificial dentition will tilt the base and ship it, if it is on an inclined foundation.

6.6. Bilateral balanceBilateral balance • Rarely found; if present it is considered balancing side interference.

• Considered necessary for base stability.

7.7. ProperioceptionProperioception • Gives the neuromuscular system control during function.

• Not present and the mandible in function will end its chewing stroke in the most favorable physiologic position, which is very close to centric relation.


Objectives of restored occlusion


Objectives of restored occlusion:

1. An acceptable interocclusal distance.

2. A stable jaw relationship with bilateral tooth contacts in retruded closure.

3. Stable tooth quadrant relationships, providing axially directed forces.

4. Multidirectional freedom of tooth contacts throughout a small range of mandibular movements.


Requirements of complete denture occlusion


Requirements of complete denture occlusion:

1. Stability of occlusion at centric relation position and in an area forward and lateral to it.

2. Balanced occlusal contacts bilaterally for all eccentric mandibular movements.

3. Unlocking the cusps mesiodistally to allow for gradual settling of



4. Control of horizontal force by buccolingual cusp height reduction according to residual ridge resistance form and interarch distance.

5. Functional lever balance by favorable tooth‑to‑ridge crest position.

6. Anterior incisal clearance during all posterior masticatory function and bruxing activity.



7. Minimum occlusal contact areas for reduced pressure in comminuting food (lingual contact occlusion).

8. Cutting, penetrating, and shearing efficiency of occlusal surfaces.

9. Sharp ridges or cusps and generous sluice ways to shear and shred food with the minimum of force necessary.


The occlusion of complete denture is divided into three

distinct units:

(a) Incising Units,

(b) Working occlusal Units, and

(c) Balancing occlusal units.


Requirement for Incising Units:

1. These units should be sharp in order to cut efficiently.

2. They should not contact during mastication.3. They should have as flat incisal guidance as

possible considering esthetics and phonetics.

4. They should have horizontal overlap to allow for base settling without interference.

5. They should contact only during protrusive incising function.


Requirements for working occlusal Units:

1. They should be efficient in cutting and grinding.2. They should have decreased buccal‑lingual

width to minimize the work force directed to the denture foundation.

3. They should function as a group with simultaneous harmonious contacts at the end of the chewing cycle and during eccentric excur sions.

4. They should be over the ridge crest in the masticating area for lever


Requirements for working occlusal Units:

5. They should have a surface to receive and transmit the force of occlusion essentially verti cally.

6. They should center the workload near the anteroposterior center of the denture.

7. They should present a plane of occlusion as parallel as possible to the mean foundation plane.


Requirements for balancing occlusal units:

1. They should contact on the second molars when the incising units contact in function.

2. They should contact at the end of the chewing cycle when the working units contact.

3. They should have smooth gliding contacts for lateral and protrusive excursions.


Theories of occlusion:

1. The Bonwill theory of occlusion.

2. The conical theory of occlusion.

3. The spherical theory of occlusion (by Monson in 1918).


The Bonwill theory of occlusion: (The theory of the equilateral triangle)

• Proposed that the teeth move in relation to each other as guided by the condylar controls and the incisal point. There is a 4‑inch (10-cm) distance between the condyles and between each condyle and the incisor point.


The conical theory of occlusion:

• Proposed that the lower teeth move over the surfaces of the upper teeth as over the surface of a Cone, generating an angle of 45 degrees with the central axis of the cone tipped 45 degrees to the occlusal plane.

• It should be noted that teeth having 45‑degree Cusps are necessary when dentures are made on this instrument.


The spherical theory of occlusion (by Monson in 1918):

• showed the lower teeth moving over the surface of the upper teeth as over the surface of a sphere with a diameter of 8 inches (20 cm). The center of the sphere was located in the region of the glabella, and the surface of the sphere passed through the glenoid fossae along or concentric with the articulating eminences.


COMPANSATING CURVES


Definition:• Compensating curves are the artificial curves

introduced into dentures in order to facilitate

the production of balanced occlusion; they

are artificial counterparts of the curves of

Spee (anteroposterior) and Monson (lateral)

which are found in the natural dentition.

• The compensating curves may be increased

or decreased in artificial dentition to help

achieve balanced occlusion.


Curve of Spee

• This curve follows an imaginary line touching the buccal cusps of all the lower teeth from the lower canine backwards. This curve forms an arc of a circle 14 cm in diameter with its center behind the crista lacrimalis.


Curve of Monson

• The curve of occlusion in which each cusp and incisal edge touches or conforms to a segment of the surface of a sphere 20 cm in diameter with its center in the region of the glabella.


All teeth and cusps contact the compensating curve


CONCEPTS OF CONCEPTS OF OCCLUSIONOCCLUSION


• A concept is a general belief

representing a class of ideas or

objects.

• Occlusal scheme for complete

dentures fall into two general

concepts:

1. Balanced occlusion, and

2. Nonbalanced occlusion.


Balanced occlusion


Definition of balanced occlusion • “ It is the bilateral, simultaneous,

anterior, and posterior occlusal contact of teeth in centric and eccentric positions (static positions)”.

• Teeth can be arranged in these static positions and observed on positional, semi adjustable and adjustable articulators; and assuming that the maxillo mandibular relation records are accurate, the contacts will be repeated in the mouth.


Definition of balanced gliding occlusion

• “ It is the even contacting of teeth as the mandible moves to and from eccentric and centric max illomandibular relations (dynamic positions)”.

• The teeth can he arranged in these dynamic positions and observed on positional and adjustable articulators, but the contacting in the mouth will not be the same.


• The concept of balanced occlusion does not occur in the natural dentition.

• A stable base is the ultimate goal.

• Total stability is not possible because of the yielding nature of the supporting structures


PRINCIPLES OF BALANCE AS PRINCIPLES OF BALANCE AS RELATED TO COMPLETE RELATED TO COMPLETE

DENTURE OCCLUSIONDENTURE OCCLUSION


Principles of balance as related to complete denture occlusion :

• The wider and larger the ridge and the closer the teeth are to the ridge, the greater the lever balance.

• Conversely, the narrower and smaller the ridge and the farther the teeth from the ridge, the poorer the lever balance.

• The wider the ridge and the narrower the teeth buccolingually, the greater the balance.



• Conversely, the narrower the ridge and the wider the teeth, the poorer the balance.

• The more lingual (inside) the teeth are placed in relation to the ridge crest, the greater the balance.

• The more buccal (outside) the teeth are positioned, the poorer the balance.


Principles of balance as related to complete denture occlusion :• The more centered the force of occlusion

anteroposteriorly, the greater the stability of the base.

• The smaller the area of occlusal surface acting on food, the smaller will be the crushing force on food transmitted to the supporting structures.

• Vertical force applied to an inclined occlusal surface causes nonvertical force on the denture base.



• Vertical forces applied to inclined-supporting tissues will cause nonvertical forces on the denture base.

• Vertical force applied to a denture base supported by yielding tissue causes the base to teeter when the force is not centered on the base.


Methods of producing occlusal balance:• Adjustable articulator techniques

• Average articulator techniques

• Hinge articulator with generated occlusal curvature techniques

• Hinge articulator and average curve techniques


Adjustable Articulator Techniques

• Sufficient data are obtained to adjust the articulator to the individual condyle paths of the patient. In addition to the usual jaw relation records is an occlusal record of the patient's protrusive position. A face‑bow registration is also taken to relate the casts to the retruded hinge axis.


Average articulator techniques

• These articulators have been designed to produce average mandibular movements, and the teeth are usually set to an average curvature of about a 100-mm radius.

• Their use has the advantage of requiring only the minimum of clinical information.

• The standard of eccentric occlusion achieved is, of course, not perfect, and a certain amount of error must be accepted in the finished denture.


Hinge articulator with generated occlusal curvature techniques

• The objective of 'grind‑in' and 'chew‑in' techniques is to modify the surface form of record blocks to harmonize with the mandibu lar movements.

• For the grind‑in technique, the blocks are made of two parts of powdered pumice and one part of plaster of Paris mixed with water. Soft wax blocks covered with tin foil are used for the chew‑in technique.

• In both techniques a template of the patient's occlusal curvature is produced, the casts are mounted on a hinge articulator, and the technician sets cuspless teeth to duplicate the curved occlusal Surface. The bases that carry the record blocks should be rigid and should fit well, because any movement of the record blocks will spoil the result.

• The degree of balanced articulation depends on the original form of the record blocks and the care given to the grinding in techniques at the chairside.

• In general, it is best to start with an occlusal surface that repre sents a segment of a 100-mm radius sphere. This is then modified by the mandibular movements of the patient.


Hinge Articulator and 'Average Curve’ 'Techniques

• These techniques do not give such good results as the other methods and their only virtue is their simplicity. All that is necessary is to supply the technician with a metal template of an average occlusal curvature to which he sets the teeth after the retruded contact registration has been made. Several different 'average' templates are but the 100-mm radius curve based on Monson’s work (1932) is most commonly used.


Factors that affect occlusal balance

1. Condylar guidance.

2. Incisal guidance angle.

3. Angulation of the occlusal plane.

4. Compensating curves.

5. Cusps on teeth or the inclination of cuspless teeth • Under the dentist’s control makes it is possible to

achieve simultaneous gliding occlusal contacts

from centric occlusion to eccentric occlusal

positions both on the articulator and in the

patient's mouth.


Non Balanced occlusion

PhilosophyOcclusal scheme1.Neutrocentric concept2.Reverse lateral curve3.Organized occ.4.Occlusal pivots5.Lingualized occ.


QUESTIONSQUESTIONS


Right or Fault? Correct the fault:1. Centric occlusion is "the static relationship between the

incising or masticating surfaces of the maxillary and mandibular teeth when they are in contact in either cen tric or eccentric jaw relation.”

2. Centric relation is the most posterior retruded unstrained position of mandible in relation to maxilla at established vertical dimension from which any eccentric movement can be done at a given degree of jaw separation.

3. Gliding occlusion is a static contact of teeth.

4. The greater/lesser degree of condylar guidance, the greater/lesser degree of posterior tooth disocclusion

5. The difference in distance between VDO and VDR is called the "interarch space”

6. Incising with the artificial teeth does not affect the posterior teeth.

basics of complete denture occlusion

Documents

posterior teeth

contacting of teeth

mandibular teeth

occlusion of opposing

tooth relation

eccentric occlusion

eccentric jaw relation

lower teeth cusp