Complete Denture

Occlusion

Rola M. Shadid, BDS, MSc

Occlusion the static relationship between

the incising or masticating surfaces of the maxillary and mandibular teeth, or tooth analogs

Articulationthe contact relationship between

the occlusal surfaces of teeth during function

• Centric occlusion

• Eccentric occlusion *

Protrusive occlusion Lateral occlusion

Working side the side toward which the

mandible moves in a lateral excursion

Non working (balancing) side that side of the mandible that

moves toward the median line in a lateral excursion.

Occlusal Schemes For CD

Balanced articulationNonbalanced articulation (linear or monoplane articulation)Lingualized articulationFunctionally generated occlusal scheme

Balanced Occlusion/Articulation

• Bilateral simultaneous contact betw. anterior & posterior teeth during all centric and eccentric positions

• There should be no interferences during movement from centric position to eccentric positions

• The movements should be in harmony with TMJ & neuromuscular control

Advantages of Balanced Occlusion

• To improve stability & retention

• To decrease soreness & resorption of residual ridge

• To improve oral comfort of the patient

Mechanics Of Balanced Occlusion

Christensen’s phenomenon*

How Could You Achieve Balanced Occlusion In CD?

Factors That Affect Occlusal Balance

Factors Affecting Balanced Occlusion (Hanau’s Quint) *

1. Condylar Guidance2.  Incisal Guidance3.  Plane of occlusion4. Cuspal inclination5. Compensating curve.

Condylar Guidance*

Mandibular guidance generated by the

condyle and articular disc traversing the contour of the glenoid fossae

The posterior determinent of mandibular movement

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

Incisal Guidance *

It’s the influence of the contacting surfaces of the mandibular & maxillary anterior teeth on mandibular movement

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

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

↓↓ Incisal Guidance Angle by ↑↑ horizontal overlap

Incisal Guidance

• For CD, the incisal guidance

should be as shallow as esthetics and phonetics will permit when arrangement of anterior teeth to reduce protrusive displacing forces

Incisal Guidance

↓ Incisal Guidance Angle by either:*

↑ horizontal overlap ↓ vertical overlap

If Increased Incisal Guidance Angle For CD?

During protrusion:

Upper denture drops at the back

Lower denture slides backward

Plane Of Occlusion

Its inclination can be altered slightly *

It is not as important as other factors

Cusp Height & Angulation *

It is the smooth gliding of the cusp tips along the cusp inclines of the opposing teeth to provide balanced articulation

Cusp Height & Angulation

•Anatomic teeth are easier to balance than nonanatomic teeth

•Cuspal inclines should not be too steep as it can increase lateral forces

•It is possible to decrease cuspal height by using compensating curves

Compensating Curves

Artificial curves introduced into complete denture occlusion to achieve balanced occlusion

Are among the most important determinents of occlusal balance

Compensating Curves

The anteroposterior curving (in the median plane) and the mediolateral curving (in the frontal plane) within the alignment of the occluding surfaces and incisal edges of artificial teeth that is used to develop balanced occlusion

The Curvatures In Natural Dentition

Curve of Spee An arc of a circle 65mm

to 70mm radius that touches the tips of all the mandibular teeth when the skull is viewed laterally; when continued it touches the anterior surface of the condyles

The Curvatures In Natural Dentition

Curve Of MonsonA proposed ideal curve of

occlusion in which each cusp and incisal edge touches or conforms to a segment of the surface of a sphere 4 inches (102mm) in radius with its centre in the region of the glabella.

Compensating Curves

Anteroposteri

or curve *

Mediolateral curve ¤

Compensating Curves The steepness of the curve

necessary to achieve balance is the result of guiding influence of angle of condylar guidance and angle of incisal guidance

It is functionally and mechanically advantageous to keep compensating curve as modest as possible → This is accomplished by setting as shallow an incisal guidance as phonetics, esthetics permit

Theilmann’s Formula

IGxCG = CHxOPxCC

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

To achieve balanced occlusion, the steeper the condylar guidance, the greater the cusp height toward the posterior or the steeper the compensating curves

According To The Formula

To achieve balanced occlusion, the steeper the compensating curves, the less the cusp height toward the posterior

QuestionQ) Suppose that the incisal guidance is set and the condylar

guidance is steeper than your chosen 20 degree teeth. To obtain balanced occlusion in your complete denture, what should you do?

a. steepen the compensating curves in both sagittal and frontal planes

b. steepen the compensating curves in only sagittal but not frontal plane

c. decrease the inclination of occlusal planed. decrease the steepness of compensating curves in both

sagittal and frontal planese. steepen the condylar guidancef. none of the above

Occlusal Schemes For CD

Philosophies of Denture Occlusion

• Many philosophies of arranging denture occlusion

• No definitive scientific studies prove one occlusal scheme clearly superior

Occlusal Schemes

Balanced articulationNonbalanced articulation (linear or monoplane articulation)Lingualized articulationFunctionally generated occlusal scheme

Max. lingual cusps Max. lingual cusps contact central contact central fossae/marginal ridgefossae/marginal ridge

~ 1mm space ~ 1mm space between buccal between buccal cuspscusps

Max. lingual cusps Max. lingual cusps contact central contact central fossae/marginal ridgefossae/marginal ridge

~ 1mm space ~ 1mm space between buccal between buccal cuspscusps

Lingualized Occlusion

Lingualized Occlusion

• Lingualized occlusion is a type of bilaterally balanced occlusal schemes *

• Anatomic teeth are used in the maxilla opposing a flat-cusped, or shallow cusped mandibular tooth.

Lingualized Occlusion • Forces directed toward lingual side• Maxillary lingual cusps articulate with

the mandibular central fossae• Elimination of contacts on the buccal

cusps in both centric and eccentric• The aim is to provide greater

masticating efficiency and the elimination of lateral interferences

Lingualized Occlusion

• Maxillary anatomic (33°)• Mandibular Teeth

• Steep Condylar Guidance • Shallow cusped

(Anatoline)• Shallow Condylar

Guidance• Non-anatomic

(Portrait 0°)

Lingualized (lingual contact)

Verify centric Verify centric No max. buccal cusp contacts in: No max. buccal cusp contacts in:

• • Centric Centric • • Lateral excursions Lateral excursions

Verify centric Verify centric No max. buccal cusp contacts in: No max. buccal cusp contacts in:

• • Centric Centric • • Lateral excursions Lateral excursions

Lingualized OcclusionLingualized Occlusion

Contraindications Of Balanced Occlusion & Lingualized Occlusion

Extreme cases of the following:

Difficulty in obtaining repeatable centric record (incoordination, jaw malrelations)

Severe ridge resorption (lateral forces displace the denture) may more easily be handled with a monoplane scheme

Monoplane Articulation (Neutrocentric Concept)

• Cuspless teeth (0°) on a flat plane with 1.5-2.0 mm overjet

• No cusp to fossa relationship

• No anterior contacts in centric position

Monoplane Articulation

• Eliminate cusps•lateral forces reduced•improves stability

• Simplifies tooth arrangement

Monoplane Articulation

• No overbite (would cause tilting)

• Overjet of 2 mm is used to create an illusion of overbite

Monoplane Articulation

• Excursions - may or may not contact on balancing sides

• Depends on condylar inclination and other aspects of the tooth arrangement

Monoplane Articulation

• Anterior teeth make contact in excursions

• Modifications have been proposed to minimize the tilting potential:• Compensating curves

Monoplane Occlusionwithout condylar influence

Monoplane Occlusion

Monoplane Articulation

Advantages• Technically easier to achieve• Use when:

–Difficulty obtaining repeatable centric records (muscle incoordination)

–Skeletal malocclusion (Class II, III)–Severe residual ridge resorption

– Reduces horizontal forces

Monoplane Articulation

Disadvantages• Poorer appearance• Can be unstable if condylar

guidance is steep (posterior teeth separate, leaving only the anteriors in contact)

Monoplane Articulation

Contraindications: • The patient has high

expectations for improved appearance

• Very steep condylar guidance may make a monoplane scheme less stable, unless modifying ramps or compensating curves are used.

When 1.5-2.0mm of overjet can be set, a lingualized occlusion (left) can have overbite set. Monplane occlusion (right) should normally have no overbite set.