dr keson b c tan bds (hons), msd
TRANSCRIPT
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
Criteria for
Optimum Functional Occlusion
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Dr Keson B C Tan BDS (Hons), MSD
“the act of closure or state of being closed”
Dorland’s Medical Dictionary
OCCLUSION Definition:
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Dr Keson B C Tan BDS (Hons), MSD
Occlusion “relationship of the maxillary
and the mandibular teeth when they are in functional contact during activity of the mandible.”
Okeson, 3rd Ed, 1993
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Dr Keson B C Tan BDS (Hons), MSD
History of Occlusion 1. Balanced Occlusion 2. Gnathology 3. Unilateral Eccentric Contacts 4. Dynamic Individual Occlusion
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Dr Keson B C Tan BDS (Hons), MSD
Balanced Occlusion • Bilateral Balance • All lateral & protrusive movements • Complete dentures
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Dr Keson B C Tan BDS (Hons), MSD
Gnathology • The exact science of mandibular
movement and resultant occlusal contacts.
• Dogmatic treatment goals. All nonconforming occlusions were considered malocclusions and were treated to “ideal”.
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Dr Keson B C Tan BDS (Hons), MSD
Unilateral Eccentric Contacts • Schuyler, Stallard, Stuart • Laterotrusive & Protrusive contacts
only on anterior teeth • Anterior Guidance
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Dr Keson B C Tan BDS (Hons), MSD
Dynamic Individual Occlusion
• No specific occlusal configuration ideal
• Physiologic Occlusion - health & function of the Masticatory System
• Physiologic configuration acceptable regardless of specific tooth contacts.
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Dr Keson B C Tan BDS (Hons), MSD
Stomatognathic Orthopedics • A concept in dentistry concerned with Postural
Relationships of the jaws • Analysis of the harmful effects of improper
craniomandibular relationships on dental and other components of the stomatognathic system;
• The Diagnoses and Correction of such malrelationship; and
• The Treatment and/or Prevention of disturbances resulting therefrom.
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Dr Keson B C Tan BDS (Hons), MSD
Orthopedics • that branch of surgery dealing with
the preservation and restoration of the function of the skeletal system, its articulations and associated structures.
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Dr Keson B C Tan BDS (Hons), MSD
Pathofunction • not only includes the abnormal function but also the pathology and the tissue changes occurring as a result of that abnormality
• a state of morphofunctional
harmony between occlusal morphology and neuromuscular function
• this range of physiologic
response may show a biologic variation from an ideal response to a state of adaptation
Orthofunction
Krough-Poulsen
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Dr Keson B C Tan BDS (Hons), MSD
Somatognathic System
Dento-Alveolar Complex
Musculature CMA
CNS
The careful study of the interactions among the three components
(i.e. the Dento-Alveolar Complex, the Craniomandibular Articulation and
the Neuromusculature).
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Dr Keson B C Tan BDS (Hons), MSD
CRITERIA FOR OPTIMUM FUNCTIONAL OCCLUSION
Which occlusal configuration is most likely to eliminate occlusal pathosis?
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Dr Keson B C Tan BDS (Hons), MSD
Treatment Goal
CRITERIA FOR OPTIMUM FUNCTIONAL OCCLUSION
1. Elimination of occlusal disorders 2. Restoration of the mutilated dentition
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Dr Keson B C Tan BDS (Hons), MSD
OPTIMUM ORTHOPEDICALLY STABLE JOINT POSITION
OPTIMUM FUNCTIONAL TOOTH CONTACTS
CRITERIA FOR OPTIMUM FUNCTIONAL OCCLUSION
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
Somatognathic System
Dento-Alveolar Complex
Musculature CMA
CNS
The careful study of the interactions among the three components
(i.e. the Dento-Alveolar Complex, the Craniomandibular Articulation and
the Neuromusculature).
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Dr Keson B C Tan BDS (Hons), MSD
CRANIOMANDIBULAR ARTICULATION
• 1. Two TMJs • 2. Teeth
Contact and force application in 3 areas
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Dr Keson B C Tan BDS (Hons), MSD
OPTIMUM ORTHOPEDICALLY STABLE JOINT POSITION
• Considered to designate the mandibular position with the condyles in an orthopedically stable position
Centric Relation
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Dr Keson B C Tan BDS (Hons), MSD
Centric Relation
• Early definition of CR • Limited by ligaments • Ligamentous Position • Reproducible - used in Complete
Denture construction
Most Retruded Position
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Dr Keson B C Tan BDS (Hons), MSD
CR (Most retruded) = MI
Ramfjord, 1961 - Most physiologic position ??
Centric Relation
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Dr Keson B C Tan BDS (Hons), MSD
Recent concepts
• Most superior position (Apex of Force position) - Dawson, 1974
• Anterior-superior position - Glossary of Prosthodontic Terms, 1987
Centric Relation
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Dr Keson B C Tan BDS (Hons), MSD
Positional Stability • Not determined by disc • Like all other joints, determined by
muscles that pull across joint • Masseters & Medial Pterygoids -
superoanterior • Temporalis - superior • Inferior Lateral Pterygoids - anteriorly,
against posterior slopes of the articular eminences
OPTIMUM ORTHOPEDICALLY STABLE JOINT POSITION = CR
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Dr Keson B C Tan BDS (Hons), MSD
Anatomical Situation
(1) Disc of dense fibrous CT, devoid of nerves and blood vessels
(2) Disc to separate, protect and stabilize condyle in mandibular fossa.
OPTIMUM ORTHOPEDICALLY STABLE JOINT POSITION = CR
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Dr Keson B C Tan BDS (Hons), MSD
Articular Disc Position • Disc morphology • Interarticular pressure • Tonus of superior lateral pterygoids • Disc rotated anteriorly on condyles as
far as allowed by: • discal spaces (determined by interarticular
pressures) • posterior border thickness
OPTIMUM ORTHOPEDICALLY STABLE JOINT POSITION = CR
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Dr Keson B C Tan BDS (Hons), MSD
• Traditional “CR” • A border ligamentous position
was considered an optimum functional position?
• Border positions not considered optimum for any other joint in the body.
RETRUDED POSITION
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Dr Keson B C Tan BDS (Hons), MSD
MOST SUPERIOR POSITION • A-P Range
? Superoposterior Most superior (Dawson)
Superoanterior (MS)
• Inner horizontal fibres of TM ligament - tight or loose
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Dr Keson B C Tan BDS (Hons), MSD
“Gelb” (4-7) Position
• Condyles halfway down posterior slopes of articular eminences
• Inferior lateral pterygoid must counter constant superior positioning action of elevators.
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Dr Keson B C Tan BDS (Hons), MSD
RETRUDED POSITION • Not physiological • Not anatomically sound • Retrodiscal tissue
– highly vascularised and innervated – not structured to accept loading
• Dry skull exam - thin bone
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Dr Keson B C Tan BDS (Hons), MSD
• Condyles in their most superoanterior position in the articular fossae
• Resting against the posterior slopes of the articular eminences
• Articular discs properly interposed • =CR
OPTIMUM ORTHOPEDICALLY STABLE JOINT POSITION
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Dr Keson B C Tan BDS (Hons), MSD
• Orthopedic joint stability maintained even with heavy elevator contraction
• Most musculoskeletally stable (MS) position of the mandible
• Similar to Dawson’s concept of CR
OPTIMUM ORTHOPEDICALLY STABLE JOINT POSITION
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Dr Keson B C Tan BDS (Hons), MSD
SUPERIOR-ANTERIOR POSITION
1. Most orthopedically sound position 2. Optimal musculoskeletally stable
position 3. Clinically reproducible for Prosthodontic
needs 4. Repeatable THA obtainable
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Dr Keson B C Tan BDS (Hons), MSD
CR LOCATING TECHNIQUES
Mandibular guiding techniques - Passive • Bimanual Manipulation (Dawson)
Muscle Seating techniques - Active • Anterior jig (Lucia) • Leaf gauge (Huffman)
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Dr Keson B C Tan BDS (Hons), MSD
Chewing Cycle Studies • Working condyle moves posterior to
MI during the final closing portion of a cycle
• Functional position? - transient • A-P range in ‘healthy’ joints - < 1 mm ?
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Dr Keson B C Tan BDS (Hons), MSD
IATROGENIC SUPERIOR-MEDIAL CLOSE-PACK POSITION OF THE CMA
• ISMCP • Synonymous with Centric Relation (CR) • A NON-Ligamentous Position • A Prosthodontic/Orthodontic CONVENIENCE
during Occlusal Rehabilitation / Reorganisation • Joint areas also loaded at MEDIAL poles once
MAXIMUM INTERCUSPATION is coordinated at that MMR
• BIOLOGICALLY ACCEPTABLE and CLINICALLY USEFUL if TMJs are HEALTHY
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Dr Keson B C Tan BDS (Hons), MSD
SELECTION OF A THERAPEUTIC
CONDYLAR POSITION
• IMSCP • LOOSE-PACK POSITIONS
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Dr Keson B C Tan BDS (Hons), MSD
Optimum Functional Tooth Contacts
Stable Occlusal Condition
Musculoskeletally Stable Joint Position
Harmony ( )
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Dr Keson B C Tan BDS (Hons), MSD
OPTIMUM FUNCTIONAL TOOTH CONTACTS
1. Effective function 2. Minimize damage to Masticatory
system • Joints • Teeth • Supporting structures
3. Accept heavy forces
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Dr Keson B C Tan BDS (Hons), MSD
Coordination of a Cybernetic Occlusal Interface at the prescribed MMR
Functional Considerations • Permissive Occlusal Specification • Directive Occlusal Specification
Parafunctional Considerations • Diurnal Clencher • Nocturnal Bruxer
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
Adaptive Mechanisms / Options Available • Avoidance engrams may be set up • Wear of offending tooth or ‘high’ restoration • Supra-eruption and/or depression
phenomena • Increased mobility due to occlusal trauma • Parafunctional erasure-type patterns may
be triggered? • Joint changes
OCCLUSAL INTERFERENCE
X ??
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Dr Keson B C Tan BDS (Hons), MSD
During Mandibular Closure • Occlusal stops • Bilateral • Even & simultaneous • Maximum no. of teeth to spread load • CR=MI
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
Direction of Forces on Teeth • Pressure vs tension
• Osseous tissue do not tolerate pressure resorption • PDL suspensory CT fibres transform occlusal load into tension
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
OPTIMUM FUNCTIONAL TOOTH CONTACTS
• Contact on: • Cusp tip - Axial • Ridge crest - Axial • Fossa bottom - Axial
• AXIAL FORCE • PDL aligned to accept and dissipate
Direction of Forces on Teeth
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Dr Keson B C Tan BDS (Hons), MSD
Direction of Forces on Teeth • Contact on :
• Incline - Tipping • HORIZONTAL FORCE
• PDL not effective in dissipating forces
• Compression & Elongation
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Axial Loading 1) Cusp tips vs Flat surfaces perpendicular
to long axis 2) Tripodisation
• Cusp vs Fossa • 3 contacts around each cusp tip
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Vertical Loading • Physiologic
Horizontal Loading • Pathologic bone responses • Neuromuscular reflexes to avoid / guard against incline contacts
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Amount of Force on Teeth • Class 3 Lever System
• Fulcrum - TMJ • Force Vector - Masseter / Medial
Pterygoid • Load - Bolus on Teeth
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
• Force on Anterior Teeth << Posterior Teeth • Canines
• Best suited to accept horizontal forces • Longest and largest root • Best crown / root ratio • Dense compact bone • Sensory afferents • Less muscle activity with canine eccentric contact
Amount of Force on Teeth
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Class 3 Lever System
Amount of Force on Teeth
OPTIMUM FUNCTIONAL TOOTH CONTACTS
Posterior Teeth >> Anterior Teeth
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Dr Keson B C Tan BDS (Hons), MSD
Canine Guidance • Disocclude or disarticulate posterior
teeth in eccentric movements
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Group Function • Several WS teeth contact during laterotrusive
movement • Canine, premolars, m-b cusp of 1st molar • Buccal cusp - to - buccal cusp contacts • Posterior WS contacts undesirable - Greater force near fulcrum and force vectors
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Mediotrusive (Balancing) Contacts • Destructive to masticatory system
• Magnitude and direction of forces • Neuromuscular responses -
increased muscle activity ?
OPTIMUM FUNCTIONAL TOOTH CONTACTS
??X
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
Protrusive Contacts • Horizontal forces best received
by anterior teeth • Anterior Guidance - disarticulate posteriors
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
• Posterior protrusive contacts • Destructive to masticatory system • Amount and direction of forces • Neuromuscular responses
Protrusive Contacts
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Posterior Teeth • Stop mandible in Closure • Axial loading
Anterior Teeth • Guide mandible in eccentric movements • Labial inclination - Axial loading not possible • Destruction of supporting structures with
heavy occlusal contacts (eg. Posterior Bite Collapse )
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
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Dr Keson B C Tan BDS (Hons), MSD
Mutually Protected Occlusion
• Occlusal contacts in CR / MI • Posterior Teeth > Anterior
Teeth
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
Postural Considerations • Posterior contacts > Anterior
contacts in all postures • Alert Feeding Posture
• Check in this position after treatment in reclined position
OPTIMUM FUNCTIONAL TOOTH CONTACTS
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Dr Keson B C Tan BDS (Hons), MSD
What is Optimal Occlusion?
Perhaps that occlusion which most provides continuing
Functional Homeostasis (One that best adapts to its changing
functions)
Moyers, 1969
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Dr Keson B C Tan BDS (Hons), MSD
PATHOFUNCTION • not only includes abnormal function but
also the pathology and the tissue changes occurring as a result of that abnormality
• A state of morphofunctional harmony between occlusal morphology and neuromuscular function
• this range of physiologic response may show a biologic variation from an ideal response to a state of adaptation
ORTHOFUNCTION
Krogh-Poulsen
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Dr Keson B C Tan BDS (Hons), MSD
Form & Function
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Dr Keson B C Tan BDS (Hons), MSD
ORTHOFUNCTION
DYSFUNCTION
DEGREE OF ADAPTATION
FORM (Occlusion)
FUNCTION (Neuromuscular
Response)
Ideal Function
Normal Function
No adaptation necessary
Wide zone of adaptation
No occlusal interferences
Occlusal Interferences a. interference with closure (IP, RCP, MCP) b. excursive interferences c. mandibular displacement
No muscular hyperactivity
Minimal muscular activity
SUBLIMINAL SYMPTOMS FUNCTIONAL DISORDERS (tissue lesions)
a. periodontium b. muscles c. joints
Narrow zone of adaptation Uncontrolled adaptation
FUNCTIONAL DISTURBANCES a. decreased function b. spasm with fatigue c. bruxism
Major or minor occlusal interferences
Increased muscle hyperactivity
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Dr Keson B C Tan BDS (Hons), MSD
PATHOLOGIC OCCLUSION
Any occlusion judged to be a causal factor in the formation of traumatic lesions or disturbances in the supporting structures of the teeth, muscles and temporomandibular joints.
DEFINITION:
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Dr Keson B C Tan BDS (Hons), MSD
Pathologic Occlusion
Whether or not an occlusion produces injury. Not how the teeth occlude.
Criterion:
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Dr Keson B C Tan BDS (Hons), MSD
Orthofunction Pathofunction
Zone of Physiologic
Tissue Response
Morphofunctional Disharmony
Zone of Adaptation
or of
Subliminal
Effects
or
Symptoms
Zone of Pathologic
Tissue Response
Morphofunctional Harmony
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Dr Keson B C Tan BDS (Hons), MSD
Asymptomatic “Supernormal”
Adaptive Orthofunction
Dysfunctional Pathofunction Functional Spectrum
All individuals can be located on continuous function spectrum ranging from “supernormal” asymptomatic status to dysfunctional.
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Dr Keson B C Tan BDS (Hons), MSD
Structural and Behavioral Objectives
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Dr Keson B C Tan BDS (Hons), MSD
Stomatognathic Orthopedics • A concept in dentistry concerned with Postural
Relationships of the jaws • Analysis of the harmful effects of improper
craniomandibular relationships on dental and other components of the stomatognathic system;
• The Diagnoses and Correction of such malrelationship; and
• The Treatment and/or Prevention of disturbances resulting therefrom.
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Dr Keson B C Tan BDS (Hons), MSD
Optimum Functional Occlusion
1a). Condyles in most superoanterior position (musculoskeletally stable), resting on the posterior slopes of the articular eminences with the discs properly interposed.
1b). Even, simultaneous contact on all posterior teeth.
1c). Anterior teeth also contact but more lightly than posterior teeth.
Summary
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Dr Keson B C Tan BDS (Hons), MSD
Summary
2. All tooth contacts provide axial loading of occlusal forces.
3. In laterotrusion, adequate tooth-guided contacts on laterotrusive (working) side to disclude mediotrusive (nonworking) side immediately. Canine guidance desirable. Group function acceptable.
Optimum Functional Occlusion
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Dr Keson B C Tan BDS (Hons), MSD
4. In protrusion, adequate tooth-guided contacts on anterior teeth to disclude all posterior teeth immediately.
5. In alert feeding posture, posterior tooth contacts remain heavier than anterior tooth contacts.
Summary
Optimum Functional Occlusion
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Dr Keson B C Tan BDS (Hons), MSD