Fundamentals of occlusion/ cosmetic dentistry training

FUNDAMENTALS OFFUNDAMENTALS OF
OCCLUSIONOCCLUSION
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTSCONTENTS
 INTRODUCTIONINTRODUCTION
 DEFINITIONDEFINITION
 TMJTMJ
 CENTRIC RELATIONCENTRIC RELATION
 MANDIBULAR MOVEMENTSMANDIBULAR MOVEMENTS
 DETERMINENTS OF OCCLUSIONDETERMINENTS OF OCCLUSION
 OCCLUSAL INTERFERENCESOCCLUSAL INTERFERENCES
 NORMAL V/S PATHOLOGIC OCCLUSIONNORMAL V/S PATHOLOGIC OCCLUSION
 VARIOUS OCCLUSAL CONCEPTSVARIOUS OCCLUSAL CONCEPTS
 CONCLUSIONCONCLUSION
 BIBLIOGRAPHYBIBLIOGRAPHY

INTRODUCTIONINTRODUCTION
 Unfortunately the occlusion of teeth isUnfortunately the occlusion of teeth is
frequently overlooked or taken for granted infrequently overlooked or taken for granted in
providing restorative dental treatment forproviding restorative dental treatment for
patients. This may be due in part to the factpatients. This may be due in part to the fact
that the symptoms of occlusal disease are oftenthat the symptoms of occlusal disease are often
hidden from the practitioner not trained tohidden from the practitioner not trained to
recognize them or to appreciate theirrecognize them or to appreciate their
significance..significance..

 The long term successful restorations areThe long term successful restorations are
dependent upon the maintenance of occlusaldependent upon the maintenance of occlusal
harmony. The minimal expectation of theharmony. The minimal expectation of the
competent practitioner is the ability tocompetent practitioner is the ability to
diagnose and treat simple occlusaldiagnose and treat simple occlusal
disharmonies. Practitioners must be able todisharmonies. Practitioners must be able to
produce restorations that will avoid theproduce restorations that will avoid the
creation of iatrogenic occlusal diseasecreation of iatrogenic occlusal disease

DEFINITION:DEFINITION:
 The static relationship between the incising orThe static relationship between the incising or
masticating surfaces of maxillary ormasticating surfaces of maxillary or
mandibular teeth or tooth (GPT-7)mandibular teeth or tooth (GPT-7)

ANATOMY OFANATOMY OF
TEMPOROMANDIBULARTEMPOROMANDIBULAR
JOINTJOINT

Collateral ligamentCollateral ligament

Capsular ligamentCapsular ligament

Temporomandibular ligamentTemporomandibular ligament

Accessory ligamentsAccessory ligaments

CENTRIC RELATIONCENTRIC RELATION
The maxillomandibular relationship in which theThe maxillomandibular relationship in which the
condyles articulate with the thinnest avascular portioncondyles articulate with the thinnest avascular portion
of their respective discs with the complex in theof their respective discs with the complex in the
anterior-superior position against the shapes of theanterior-superior position against the shapes of the
articular eminences. This position is independent ofarticular eminences. This position is independent of
tooth contact. This position is clinically discernibletooth contact. This position is clinically discernible
when the mandible is directed superiorly andwhen the mandible is directed superiorly and
anteriorly. It is restricted to a purely rotary movementanteriorly. It is restricted to a purely rotary movement
about the transverse horizontal axis. (GPT-5)about the transverse horizontal axis. (GPT-5)

MANDIBULAR MOVEMENTSMANDIBULAR MOVEMENTS

SAGITTAL PLANESAGITTAL PLANE

HORIZONTAL PLANEHORIZONTAL PLANE::

FRONTAL PLANEFRONTAL PLANE::

Transverse hinge axisTransverse hinge axis

BENNETT MOVEMENTBENNETT MOVEMENT

BENNETT ANGLEBENNETT ANGLE

 86% of condyle had immediate or early lateral86% of condyle had immediate or early lateral
translation.translation.
 Lundeen and Wirth used mechanicalLundeen and Wirth used mechanical
apparatus, showed a median dimension to beapparatus, showed a median dimension to be
approximately 1.0mm to max of 3mm.approximately 1.0mm to max of 3mm.
 Hobo and Mochizuki used electronicHobo and Mochizuki used electronic
measuring device found 0.4mm to 2.6mm ofmeasuring device found 0.4mm to 2.6mm of
immediate lateral translation.immediate lateral translation.

 Progressive side shift or bennett side shift.Progressive side shift or bennett side shift.
 Lundeen and Wirth found slight variation inLundeen and Wirth found slight variation in
the direction of progressive lateral translationthe direction of progressive lateral translation
or bennett angle with a mean value of 7.5or bennett angle with a mean value of 7.5
degree.degree.
 Hobo and Mochizuki foung a much greaterHobo and Mochizuki foung a much greater
variation ranging from1.5 to 36 degree with avariation ranging from1.5 to 36 degree with a
mean value of 12.8degree.mean value of 12.8degree.

DETERMINENTS OFDETERMINENTS OF
OCCLUSIONOCCLUSION
 Posterior determinentsPosterior determinents
 Anterior determinentsAnterior determinents
 Neuromuscular systemNeuromuscular system

Posterior determinentsPosterior determinents
 Rt and lt temporomandibular joints.Rt and lt temporomandibular joints.
 No control over it.No control over it.
 Condylar path is the basis for the use ofCondylar path is the basis for the use of
articulator.articulator.

Anterior determinantsAnterior determinants
 Teeth.Teeth.
 Posterior teeth – vertical stops for closure.Posterior teeth – vertical stops for closure.
Also guide the mandible to maximumAlso guide the mandible to maximum
inercuspationinercuspation
 Anterior teeth – guide the mandible in lateralAnterior teeth – guide the mandible in lateral
excursive and in protrusive movements.excursive and in protrusive movements.

 Anterior teeth are suited for guidance 1)caninesAnterior teeth are suited for guidance 1)canines
having longest, strongest roots.having longest, strongest roots.
2)the load being reduced by distance from the2)the load being reduced by distance from the
fulcrum.fulcrum.
3)the proprioceptive threshold and concomitant3)the proprioceptive threshold and concomitant
reflexes reducing the load.reflexes reducing the load.
 Dentist have direct control over the toothDentist have direct control over the tooth
determinants by orthodontic movement, restoration ofdeterminants by orthodontic movement, restoration of
anterior lingual or posterior occlusal surfaces,anterior lingual or posterior occlusal surfaces,
selective grinding.selective grinding.

Neuromuscular systemNeuromuscular system
 The neuromuscular system, throughThe neuromuscular system, through
proprioceptive nerve endings in theproprioceptive nerve endings in the
periodontium, muscles and joints monitor theperiodontium, muscles and joints monitor the
position of the mandible and its path ofposition of the mandible and its path of
movement.movement.
 Indirect control over it.Indirect control over it.

Effects of anatomic determinantsEffects of anatomic determinants

Molar disocclusionMolar disocclusion
 Normal occlusions perform repeated lateralNormal occlusions perform repeated lateral
mandibular movements, they will not trace themandibular movements, they will not trace the
same path on electronic recordings due tosame path on electronic recordings due to
flexible nature of articular disc.flexible nature of articular disc.
 The measurement deviation averages 0.2mmThe measurement deviation averages 0.2mm
in centric relation, 0.3mm in working, andin centric relation, 0.3mm in working, and
0.8mm in both protrusive and nonworking0.8mm in both protrusive and nonworking
movementsmovements

 Healthy natural occlusions exhibit clearancesHealthy natural occlusions exhibit clearances
that will accommodate these aberrations.that will accommodate these aberrations.
 Measurement of disocclusions from theMeasurement of disocclusions from the
mesiobuccal cusp tips of the mandibular firstmesiobuccal cusp tips of the mandibular first
molar in asymptomatic test subjects with goodmolar in asymptomatic test subjects with good
occlusions showed separations averagingocclusions showed separations averaging
0.5mm in working , 1.0mm in nonworking and0.5mm in working , 1.0mm in nonworking and
1.1mm in protrusive movement.1.1mm in protrusive movement.

 Therefore one of the treatment goals in placingTherefore one of the treatment goals in placing
occlusal restorations should be to produce aocclusal restorations should be to produce a
posterior occlusion with buffer space thatposterior occlusion with buffer space that
equals or surpasses the deviations resultingequals or surpasses the deviations resulting
from natural variations found in thefrom natural variations found in the
temporomandibular joint.temporomandibular joint.

Condylar guidanceCondylar guidance
*Protrusive condylar inclination – average 30.4*Protrusive condylar inclination – average 30.4
degree.degree.
- steep- steep
- shallow- shallow
*mandibular lateral translation*mandibular lateral translation

Immediate lateral translationImmediate lateral translation

 Ridge and groove directions are affected byRidge and groove directions are affected by
the condylar path, particularly lateralthe condylar path, particularly lateral
translation. The effect was observed on thetranslation. The effect was observed on the
occlusal surface of a mandibular molar andocclusal surface of a mandibular molar and
premolar.premolar.
 The working path is traced on the mandibularThe working path is traced on the mandibular
tooth in lingual direction and nonworking pathtooth in lingual direction and nonworking path
is in a distobuccal direction.is in a distobuccal direction.

 Nearer the tooth is to the working side condyleNearer the tooth is to the working side condyle
anteroposteriorly, the smaller the angleanteroposteriorly, the smaller the angle
between the working and nonworking pathsbetween the working and nonworking paths

Anterior guidanceAnterior guidance
 Protrusive incisal path inclination – 50 to 70Protrusive incisal path inclination – 50 to 70
degrees.degrees.

FactorFactor ConditionCondition EffectEffect
CondylarCondylar
guidanceguidance
SteeperSteeper TallerTaller
AnteriorAnterior
guidanceguidance
More overbiteMore overbite
More OverjetMore Overjet
TallerTaller
ShorterShorter
Plane ofPlane of
occlusionocclusion
More parallelMore parallel ShorterShorter
Curve ofCurve of
SpeeSpee
More acuteMore acute ShorterShorter
LateralLateral
translationtranslation
Greater movementGreater movement ShorterShorter

FactorFactor ConditionCondition EffectEffect
Distance fromDistance from
rotating condylerotating condyle
GreaterGreater Wider the angleWider the angle
Distance fromDistance from
midsagittal planemidsagittal plane
GreaterGreater Wider the angleWider the angle
Lateral translationLateral translation GreaterGreater Wider the angleWider the angle
IntercondylarIntercondylar
distancedistance
GreaterGreater Smaller the angleSmaller the angle

Occlusal interferencesOcclusal interferences
 CentricCentric
 WorkingWorking
 NonworkingNonworking
 protrusiveprotrusive

Centric interferenceCentric interference

Working interferenceWorking interference

Nonworking interferenceNonworking interference

Protrusive interferenceProtrusive interference

NORMAL V/S PATHOLOGICNORMAL V/S PATHOLOGIC
OCCLUSIONOCCLUSION
 10% population with complete hormony according to10% population with complete hormony according to
old conceptold concept
 In majority of population, the maximumIn majority of population, the maximum
intercuspation causes the mandible to be deflectedintercuspation causes the mandible to be deflected
away from its optimum position.away from its optimum position.
 In the absence of symptoms, this is consideredIn the absence of symptoms, this is considered
physiologic or normal .physiologic or normal .
 So in physiologic occlusion teeth will be in theSo in physiologic occlusion teeth will be in the
maximum intercuspation and condyle in the lessmaximum intercuspation and condyle in the less
optimal position.optimal position.

 Patient ability to adapt may be influenced byPatient ability to adapt may be influenced by
the effects of psychic stress and emotionalthe effects of psychic stress and emotional
tensions on CNS.tensions on CNS.
 Lowering the threshold, leads toLowering the threshold, leads to
parafunctional activity.parafunctional activity.
 Normal occlusion becomes the pathologic one.Normal occlusion becomes the pathologic one.

Okesons criteria for optimal occlusion;Okesons criteria for optimal occlusion;
1.1. In closure, the condyles are in the mostIn closure, the condyles are in the most
superoanterior position against the discs onsuperoanterior position against the discs on
the posterior slopes of the eminences of thethe posterior slopes of the eminences of the
glenoid fossae. The posterior teeth are inglenoid fossae. The posterior teeth are in
solid and even contact and the anterior teethsolid and even contact and the anterior teeth
are in slightly lighter contact.are in slightly lighter contact.
2.2. Occlusal forces are in the long axes of theOcclusal forces are in the long axes of the
teethteeth

3. In lateral excursions of the mandible, working3. In lateral excursions of the mandible, working
side contacts disocclude or separate theside contacts disocclude or separate the
nonworking teeth instantly.nonworking teeth instantly.
4. In protrusive excursions, anterior tooth4. In protrusive excursions, anterior tooth
contacts will disocclude the posterior teeth.contacts will disocclude the posterior teeth.
5. In an upright posture, posterior teeth contact5. In an upright posture, posterior teeth contact
more heavily than do anterior teeth.more heavily than do anterior teeth.

Occlusal conceptsOcclusal concepts
 Bilateral balanced occlusionBilateral balanced occlusion
 Unilateral balanced occlusionUnilateral balanced occlusion
 Mutually protected occlusionMutually protected occlusion

Bilateral balanced occlusionBilateral balanced occlusion
 Von spee and MonsonVon spee and Monson
 Very difficult to achieve.Very difficult to achieve.
 High rate of failure.High rate of failure.
 Excessive frictional wear.Excessive frictional wear.
 Increased periodontal breakdown andIncreased periodontal breakdown and
neuromuscular disturbance.neuromuscular disturbance.

Unilateral balanced occlusionUnilateral balanced occlusion
 SchuylerSchuyler
 Distributes the occlusal load on working sideDistributes the occlusal load on working side
 Prevents the teeth from oblique directed forcesPrevents the teeth from oblique directed forces
on non-working side.on non-working side.
 Saves centric holding cusps from excessiveSaves centric holding cusps from excessive
wear.wear.
 Maintainance of occlusion.Maintainance of occlusion.

Group function occlusion

Mutually protected occlusionMutually protected occlusion
 D’Amico, stuart and stallard.D’Amico, stuart and stallard.
 Maximum intercuspation coincides with theMaximum intercuspation coincides with the
optimal condylar positionoptimal condylar position
 All posterior teeth are in contact and forcesAll posterior teeth are in contact and forces
directed along the long axes.directed along the long axes.
 Anterior teeth either lightly contact of veryAnterior teeth either lightly contact of very
slight out of contact (25microns)slight out of contact (25microns)

Canine guided occlusion

 Easy of fabrication and greater tolerance byEasy of fabrication and greater tolerance by
the patients.the patients.
 Anterior teeth should be periodontally healthyAnterior teeth should be periodontally healthy
 Depends on the orthodontic relation of theDepends on the orthodontic relation of the
opposing arches.opposing arches.
 Cannot be used in reverse occlusion or crossCannot be used in reverse occlusion or cross
bite.bite.

conclusionconclusion
 Occlusion is the integrated relationship of the toothOcclusion is the integrated relationship of the tooth
periodontium, TMJ and neuromusculature, and notperiodontium, TMJ and neuromusculature, and not
merely the interdigitation of the tooth. There is amerely the interdigitation of the tooth. There is a
complex interaction of many components ofcomplex interaction of many components of
masticatory system. Changes in one component affectmasticatory system. Changes in one component affect
the entire system. The dentist who practice restorativethe entire system. The dentist who practice restorative
dentistry should appreciate their significance for thedentistry should appreciate their significance for the
long term successful restorations by maintaining thelong term successful restorations by maintaining the
occlusal integrity.occlusal integrity.

BibliographyBibliography
 Okeson JP. Management ofOkeson JP. Management of
Temporomandibular Disorders andTemporomandibular Disorders and
Occlusion, ed. 4th, 1998; Mosby .Occlusion, ed. 4th, 1998; Mosby .
 Shillingburg HT. Fundamentals of FixedShillingburg HT. Fundamentals of Fixed
Prosthodontics, ed.3rd.Prosthodontics, ed.3rd.
 Rosenstiel S.F. Contemorary FixedRosenstiel S.F. Contemorary Fixed
Prosthodontics, 3rd edition.Prosthodontics, 3rd edition.
 Glossary of prosthodontics terms – 7thGlossary of prosthodontics terms – 7th
edition, 1999.edition, 1999.

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