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    Occlusion Occlusion Presentation Transcript

    • OCCLUSION IN OPERATIVE DENTISTRY INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
    • CONTENTS  INTRODUCTION  GENERAL DESCRIPTION  GOALS FOR COMPLETE DENTISTRY  RESPONSE TO HIGH RESTORATION  OCCLUSAL DISEASE  TMJ  MASTICATORY MUSCULATURE  MANDIBULAR MOVEMENT  POSSELT'S MOTION  OCCLUSAL SCHEMES  CENTRIC OCCLUSION  CENTRIC RELATION  DETERMINING CENTRIC RELATION  LOAD TESTING OF TMJ‟S  RECORDING CENTRIC RELATION  CLASSIFICATION OF OCCLUSION  DETERMINANTS OF OCCLUSION  THE PLANE OF OCCLUSION  POSTERIOR OCCLUSION  ROLE OF CONTACT AREAS  ROLE OF CONTOUR  ROLE OF MARGINAL RIDGES  SIGNS OF INSTABILITY OF OCCLUSION  REQUIREMENTS FOR EQILIBRIUM OF THE MASTICATORY SYTEM  REQUIREMENTS FOR OCCLUSAL STABILITY  OCCLUSAL EQUILIBRATION  VERIFICATION OF COMPLETION  COMPUTER ASSISTED DYNAMIC OCCLUSALANALYSIS  DENTITION – OCCLUSAL EXAMINATION  TREATMENT PLANNING CONFORMATIVE APPROACH  CONCLUSION  REFERENCES www.indiandentalacademy.com
    • INTRODUCTION  Occlusion literally means “closing”.  When the jaws are closed and teeth are in contact, this is termed as “static” occlusion.  However, occlusion mainly occurs as momentary contacts during mandibular movements and is termed as “Dynamic occlusion”.  “The contact of teeth in opposing dental arches, when they are in contact (static) and during various jaw movements (dynamic)” – STURDEVANT. www.indiandentalacademy.com
    • GENERAL DESCRIPTION  Blunt, rounded or pointed projections of the crowns of the tooth - Cusps  Cusps are separated by distinct Developmental grooves  The facial cusps are separated from lingual cusps by a deep groove - central groove  If a tooth has multiple facial or lingual cusps, the cusps are separated by facial or lingual Developmental grooves  Depressions between the cusps - Fossae  Grooves having noncoalesced enamel – Fissures  Noncoalesced enamel at the deepest point of awww.indiandentalacademy.com
    • • Operative Dentistry follows the concept of functional or physiologic occlusion. • The functional occlusion is one which can function efficiently without pain & remains in a state of health regardless of the relationship between the maxillary and mandibular teeth. • A dental examination is complete if it identifies all factors that are capable of causing or contributing to deterioration of oral health or function. www.indiandentalacademy.com
    • GOALS FOR COMPLETE DENTISRTY  Freedom from disease in all masticatory system structures  Maintaining healthy periodontium  Stable TMJ‟s  Stable occlusion  Maintaining healthy teeth  Optimum esthetics www.indiandentalacademy.com
    • RESPONSE TO HIGH RESTORATION  Tooth ache  Tooth tender on biting  Tooth wear  Spastic masticatory muscles  Muscle tension headache  Condyle / disk derangement  Degenerative arthritic changes in the TMJ‟s www.indiandentalacademy.com
    • OCCLUSAL DISEASE  Occlusal disease is deformation or disturbance of function of any structures within the masticatory system that are in disequilibrium with a harmonious interrelationship between the TMJ’s, the masticatory musculature & the occluding surfaces of the teeth  Abrasion : wear due to friction between a tooth and an exogenous agent  Erosion : tooth surface loss due to chemical or electrochemical action  Abfraction : stress induced non-carious cervicalwww.indiandentalacademy.com
    • ATTRITIONAL WEAR  Attrition : wear due to tooth-to-tooth friction  Mostly in the lower anterior teeth  Causes : 1. Deflective incline interferences of posterior teeth to centric relation forward slide of mandible during closure collision of lower anteriors with upper anteriors.2. Improper restorations on anterior teeth 3. Direct interference of the anterior teeth to complete closure in centric relationwww.indiandentalacademy.com
    • SPLAYED TEETH  Forward movement of upper anteriors  Cause : Improperly contoured restorations that are too thick on the lingual of upper anteriors or overcontoured lower restorations. SENSITIVE TEETHTOOTH • Cause : occlusal overload pulp hyperemia / noncarious cervical cracks www.indiandentalacademy.com
    • SPLIT TEETH / FRACTURED CUSPS  Cause : interference of cusp incline with strong occlusal force PAINFUL MUSCULATURE • Cause : Deflective occlusal interference Disharmony between the occlusion &TMJ’s www.indiandentalacademy.com
    • TMJ  All occlusal analysis starts at the TMJ www.indiandentalacademy.com
    •  As the TMJ is a stress bearing joint, all of the articular surfaces of the condyle, the fossa & the eminence are covered with avascular layers of dense fibrous connective tissue  TMJ is nourished by synovial fluids that lubricate the joint for smooth gliding function UNDERSTANDING CONDYLE DISK ALIGNMENT Medial & lateral Diskal ligament Posterior ligament Superior elastic stratum Superior lateral Pterygoid musclewww.indiandentalacademy.com
    •  The axial rotation occurs around a true hinge axis when the condyles are fully seated.  Rotation around a fixed horizontal axis seems improbable because of angulation of the condylles in relation to the horizontal axis  The condyles serve as bilateral fulcrum for the mandible & so the joints are always subjected to compressive forces whenever the elevator muscles contract. www.indiandentalacademy.com
    • MASTICATORY MUSCULATURE  Muscles of mastication : Masseter Temporalis Lateral / External pterygoid Medial / Internal pterygoid www.indiandentalacademy.com
    •  Centric relation (CR) is the position of the mandible when the condyles are positioned superiorly in the fossae in healthy TMJs.  This position is independent of tooth contacts.  Rotation with the condyles positioned in CR is termed terminal hinge (TH) movement.  TH is used in dentistry as a reference movement for construction of restorations.  Initial contact between teeth during a TH closure provides a reference point, termed centric occlusion (CO).  Many patients have a small slide from CO to MI, typically in a forward and superior direction. MANDIBULAR MOVEMENT www.indiandentalacademy.com
    •  Maximum rotational opening in TH is 25 mm measured between the incisal edges of the anterior teeth  Simultaneous, direct anterior movement of both condyles, or mandibular forward thrusting, is termed protrusion.  The mandible can protrude approximately 10 mm.  complex motion combines rotation and translation in a single movement.  Most mandibular movement during speech, chewing, and swallowing consists of both rotation and translation.  Maximum opening is approximately 50 mm. www.indiandentalacademy.com
    •  Lateral movement is often described with respect to only one side of the mandible for the purpose of defining the relative motion of the mandibular to the maxillary teeth.  Mandibular pathways directed away from the midline are termed working (laterotrusion & function), and mandibular pathways directed toward the midline are termed nonworking (mediotrusion, nonfunction & balancing).  Lateral movement is approximately 10 mm. www.indiandentalacademy.com
    • Bennet movement :  The rotation of the working side condyle in it‟s articular fossa results in a slight lateral movement of the condyle. This lateral movement of the condyle averages „1 mm‟ in extent and is termed the “Bennet movement” or the „immediate side shift.‟  This movement may be straight lateral, lateral and anterior; lateral and distal; lateral and superior or lateral and inferior. Bennet angle:  The mean angle formed by the sagittal plane and the path of the non-working condyle as viewed in the horizontal plane is termed the “Bennet angle”. www.indiandentalacademy.com
    • POSSELT'S MOTION  In 1952, Posselt described the capacity of motion of the mandible. The resultant diagram has been termed Posselt's motion (known as the “Envelope of motion”).  The path of the mandible during its movement in each of the possible three directions (sagittal, horizontal & vertical) is described to points beyond which the mandible is not capable of further movement.  These points are defined as the border limitation of mandibular movements, and moving the mandible to these points is therefore called “border movements of the mandible”. Centric relation Centric occlusion Protrusion Hinge movement (terminal arc of opening) max. jaw opening www.indiandentalacademy.com
    • OCCLUSAL SCHEMES Three basic schemes of occlusion : Balanced occlusion Canine protected occlusion Group function occlusion  It is defined as “the simultaneous, bilateral contacting of maxillary and mandibular teeth in anterior & posterior occlusal areas in centric and eccentric positions  This concept was applied to restoration of natural dentition by Mc Collum & Schuyler et.al.,  Seen in case of advanced attrition case  In natural teeth, balancing side contacts are inappropriate and potentially harmful as they constitute premature contacts and were proposed to cause occlusal wear, pdl breakdown, & TMJ disturbances. BALANCED OCCLUSION www.indiandentalacademy.com
    •  As the muscles move the mandible to the working side, the tip or the distobuccal incline of the lower working side canine glides down the palatal incline of the upper working side canine. This causes the mandible to move laterally, forwards and to open. This is termed „Canine guidance‟ & the concept of occlusion as „Canine protected occlusion‟  On a canine guided working movement the premolars & molars on the working side become separated as the mandible moves away from centric occlusion.  All the teeth on the non-working side also become separated as the mandible moves away from centric occlusion. CANINE PROTECTED OCCLUSION www.indiandentalacademy.com
    •  There is simultaneous gliding contact of teeth on the lateral & protrusive side during lateral & protrusive movement.  Group function is seen on all the working side teeth.  The incisal edges of the' mandibular anterior teeth glide down the palatal surfaces of the maxillary anterior teeth. UNILATERAL BALANCED / GROUP FUNCTION OCCLUSION  The buccal inclines of the buccal cusps of the mandibular premolars and molars glide against the palatal inclines of the buccal cusps of the maxillary premolars and molars.  Tooth guided working guidance continues until the guiding teeth on the working side meet in an edge to edge relation.  Further movement towards the working side is guided by contact of the upper and lower incisors. This is termed 'cross over'. www.indiandentalacademy.com
    • CENTRIC OCCLUSION  It is the position of maximum intercuspation of teeth which is in harmony with the neuromuscular mechanism.  This is not the most retruded position of the mandible www.indiandentalacademy.com
    •  Centric occlusal contacts should be checked in both functional & non-functional occlusion.  Functional occlusion occurs in the segments of arch toward which the mandible moves & is divided into lateral functional & protrusive functional occlusion  Lateral functional occlusion is predominantly guided by canines but involves sharing of contact by other posterior teeth in the functional working segment  Facial range – Mn Facial cusps moving facially & distally across the lingual inclines of Mx Facial cusps  Lingual range – Mx Palatal cusps moving across the facial inclines of Mn lingual cusps  In Protrusive functional occlusion, all Mn anterior teeth will contact along the palatal inclines of Mx anterior teeth with the disclussion of posterior teethwww.indiandentalacademy.com
    •  Non functional occlusion or balancing contacts are undesirable in the natural dentition.  Non functional occlusion is divided into lateral non-functional & protrusive non-functional occlusion  In lateral non-functional occlusion, the Mn facial cusps on the non-functioning side move obliquely, lingually & mesially towards the Mx palatal cusps along their facial inclines  Protrusive non-functional occlusion occurs in facial & lingual range  The facial range of Protrusive non-functional occlusion occurs when the mesial cusp ridges of Mn facial cusps contact the distal slopes of triangular ridges of Mx facial cusps  The lingual range of Protrusive non-functional contact occurs when the distal cusp ridges of Mx palatal cusps contact the mesial slopes of triangular ridges of Mn lingual cusps. www.indiandentalacademy.com
    • POTENTIAL CONTACT AREAS OF OCCLUSAL SURFACES MAXILLARY POSTERIOR MANDIBULAR POSTERIOR ZONE 1 Facial range in Lateral functional contact Lingual inclines of facial cusps Facial inclines of facial cusps ZONE 2 Facial range in Centric contact Central groove area Facial cusp tips ZONE 3 Lateral non-functional contact Facial inclines of palatal cusps Lingual inclines of facial cusps ZONE 4 Lingual range in Centric contact Lingual cusp tips Central groove area ZONE 5 Lingual range in Lateral functional contact Lingual inclines of palatal cusps Facial inclines of lingual cusps www.indiandentalacademy.com
    • CENTRIC RELATION  Centric Relation Is the relationship of the mandible to the maxilla when the properly aligned condyle-disc assemblies are in the most superior position against the eminentiae irrespective of vertical dimension or tooth position  Centric relation refers to both position & condition of the condyle-disk assemblies.  The condyles can freely rotate on a fixed axis in centric relation upto 20 mm of jaw opening with out moving out of fully seated position in their respective fossa.  Centric relation is an interference-free occlusion.  The rotating condyles are free to move down & up the eminence to & from centric relation, permitting the jaw to open or close at any position from centric relation to most protruded. www.indiandentalacademy.com
    • PROCEDURE – BILATERAL MANIPULATION 1 . Recline the patient all the way back DETERMINING CENTRIC RELATION / ADAPTED CENTRIC POSTURE www.indiandentalacademy.com
    • 1 . Recline the patient all the way back 2 . Head stabilization PROCEDURE – BILATERAL MANIPULATION DETERMINING CENTRIC RELATION / ADAPTED CENTRIC POSTURE www.indiandentalacademy.com
    • 1 . Recline the patient all the way back 2 . Head stabilization 3 . Stretch the neck by lifting the patient‟s chin PROCEDURE – BILATERAL MANIPULATION DETERMINING CENTRIC RELATION / ADAPTED CENTRIC POSTURE www.indiandentalacademy.com
    • 1 . Recline the patient all the way back 2 . Head stabilization 3 . Stretch the neck by lifting the patient‟s chin 4 . Place the four fingers on lower border of the mandible PROCEDURE – BILATERAL MANIPULATION DETERMINING CENTRIC RELATION / ADAPTED CENTRIC POSTURE www.indiandentalacademy.com
    • 1 . Recline the patient all the way back 2 . Head stabilization 3 . Stretch the neck by lifting the patient‟s chin 4 . Place the four fingers on lower border of the mandible 5 . Bring the thumbs together to form a „c‟ with each hand PROCEDURE – BILATERAL MANIPULATION DETERMINING CENTRIC RELATION / ADAPTED CENTRIC POSTURE www.indiandentalacademy.com
    • 1 . Recline the patient all the way back 2 . Head stabilization 3 . Stretch the neck by lifting the patient‟s chin 4 . Place the four fingers on lower border of the mandible 5 . Bring the thumbs together to form a „c‟ with each hand 6 . With a very gentle touch, manipulate the jaw so it slowly hinges open and PROCEDURE – BILATERAL MANIPULATION DETERMINING CENTRIC RELATION / ADAPTED CENTRIC POSTURE www.indiandentalacademy.com
    • DIRECTLY FABRICATED ANTERIOR DEPROGRAMMING DEVICE www.indiandentalacademy.com
    • DIRECTLY FABRICATED ANTERIOR DEPROGRAMMING DEVICE THE PANKEY JIG Dr. Keith Thornton www.indiandentalacademy.com
    • DIRECTLY FABRICATED ANTERIOR DEPROGRAMMING DEVICE THE PANKEY JIG Dr. Keith Thornton THE BEST-BITE APPLIANCE www.indiandentalacademy.com
    • DIRECTLY FABRICATED ANTERIOR DEPROGRAMMING DEVICE THE PANKEY JIG Dr. Keith Thornton THE BEST-BITE APPLIANCE THE LUCIA JIG Lucia, Dr.Peter Neff www.indiandentalacademy.com
    • DIRECTLY FABRICATED ANTERIOR DEPROGRAMMING DEVICE THE PANKEY JIG Dr. Keith Thornton THE BEST-BITE APPLIANCE THE LUCIA JIG Lucia, Dr.Peter Neff Leaf Gauge Dr.Hart www.indiandentalacademy.com
    • LOAD TESTING OF TMJ‟S  Not done to force the condyle into centric relation done to check centric relation  Done in increments  Any sign of pain – condyle on affected side is not fully seated  Reasons for tenderness : Intracapsular disorder Occlusal interferences  Mistakes done during load testing : Applying too much pressure too soon Not applying enough upward loading force www.indiandentalacademy.com
    • RECORDING CENTRIC RELATION CRITERIA FOR ACCURACY IN MAKING AN INTEROCCLUSAL BITE RECORD  The bite record must not cause any movement of teeth or displacement of soft tissue.  It must be possible to verify the accuracy of the interocclusal record in the mouth  The bite record must fit the casts as accurately as it fits the mouth  It must be possible to verify the accuracy of the bite record on the casts.  The bite record must not distort during storage or transportation to the laboratorywww.indiandentalacademy.com
    • WAX BITE RECORD  Most popular method.  Delar wax – thick at front  Technique : www.indiandentalacademy.com
    • WAX BITE RECORD  Most popular method.  Delar wax – thick at front  Technique : www.indiandentalacademy.com
    • WAX BITE RECORD  Most popular method.  Delar wax – thick at front  Technique : www.indiandentalacademy.com
    • WAX BITE RECORD  Most popular method.  Delar wax – thick at front  Technique : www.indiandentalacademy.com
    • WAX BITE RECORD  Most popular method.  Delar wax – thick at front  Technique : www.indiandentalacademy.com
    • ANTERIOR STOP TECHNIQUE www.indiandentalacademy.com
    • ANTERIOR STOP TECHNIQUE www.indiandentalacademy.com
    • CLASSIFICATION OF OCCLUSIONS ANGLE‟S CLASSIFICATION www.indiandentalacademy.com
    •  In normal Class I occlusion, the mandibular facial cusp contacts the maxillary premolar mesial marginal ridge and the maxillary premolar lingual cusp contacts the mandibular distal marginal ridge. Because only one antagonist is contacted, this is termed a tooth-to-tooth relationship.  The most stable relationship results from the contact of the supporting cusp tips against the two marginal ridges, termed a tooth-to-two-tooth contact.  In Class II occlusion, each supporting cusp tip will occlude in a stable relationship with the opposing mesial or distal fossa; this relationship is a cusp fossa contact. INTERARCH TOOTH RELATIONSHIPS www.indiandentalacademy.com
    • DAWSON‟S CLASSIFICATION Type I : Maximal intercuspation is in harmony with centric relation  Centric relation is verifiable with the teeth separated.  Jaw can close to maximal intercuspation without premature tooth contacts Type IA : Maximal intercuspation occurs in harmony with adapted centric posture  Adapted condition to – Intracapsular deformation  TMJ‟s can accept loading with no discomfort www.indiandentalacademy.com
    • TYPE II : Condyles must displace from a verifiable centric relation for maximum intercuspation to occur TYPE IIA : Condyles must displace from an adapted centric posture for maximum intercuspation to occur  The source of pain will be in muscle or in interfering tooth  The occlusal therapy goal is to achieve Type I or IA www.indiandentalacademy.com
    • TYPE III: Centric relation can not be verified  TMJ‟s cannot accept loading without tenderness  Focus should be on correcting the TMD before occlusal treatment can be finalised  The occlusal therapy goal is to achieve Type I or IA TYPE IV : The occlusal relationship is in an active stage of progressive disorder because of pathologically unstable TMJ’s  Actively progressive disorder of the TMJ’s  Signs : progressive anterior open bite progressive asymmetry progressive mandibular retrusion  The goal is to stop the progression of the TMJ’s defprmation www.indiandentalacademy.com
    • DETERMINANTS OF OCCLUSION  FIRST DETERMINANT OF OCCLUSION : Condylar path  SECOND DETERMINANT OF OCCLUSION : Anterior guidance  In a perfected occlusion, the combination of both Condylar guidance & Anterior teeth guidance www.indiandentalacademy.com
    • CONDYLAR GUIDANCE  It refers to the path that the horizontal rotational axis of the condyles travel during normal mandibular opening.  It includes : Translation of condyles Bennett shift Inter-condylar distance  Both the condyles translate simultaneously along their eminences in protrusive functional movement.  In lateral functional movements, the condyles on non- functional side translates forward along the eminence while the condyle on working side rotates in its fossa. TRANSLATION OF CONDYLES www.indiandentalacademy.com
    •  Bennett shift is the lateral bodily shift of the mandible towards the working side in function.  The amount of lateral shift influences the pattern of tooth contact during lateral movement.  The inter-condylar distance affects the path of lateral functional movement of mandible since it determines the location of vertical axis of rotation in relation to mandibular arch.  The farther the condyles are from midsaggital plane, the more anterior is the path of lateral excursion and vice versa. INTER-CONDYLAR DISTANCE BENNETT SHIFT www.indiandentalacademy.com
    •  In Restorative treatment, restriction of the envelope of function is the most problematic.  Restorations must be in hormany with the envelope of function  Incisal edges too far back  Incisal edges too far forward  When restoring upper anterior teeth, the lingual contours must be in harmony with the envelope of function from centric relation contact to incisal edge positions. ANTERIOR GUIDANCE www.indiandentalacademy.com
    • Lower incisal edges definite labio-incisal line angle Determination of horizontal Position for upper incisal edges Determination of horizontal position for lower incisal edges Exact position & contour of incisal edge Determination of contour of the anterior guidance www.indiandentalacademy.com
    • THE PLANE OF OCCLUSION  It is an imaginary surface that theoretically touches the incisal edges of the incisors and the tips of the occluding surfaces of the posterior teeth.  The curvatures of posterior plane of occlusion are divided into : Curve of Spee Curve of Wilson www.indiandentalacademy.com
    • CURVE OF SPEE  Antreroposterior curvature of the occlusal surface, beginning at the tip of lower canine & following the buccal cusp tips of bicuspids & molars and continuing to the anterior border of ramus  If the curved line continues further back, it would follow an arc through the condyle, with a 4 inch radius  The curve results from variations in axial alignment of the lower teeth parallel with its arc of closure. This requires the last molar to be inclined at the greatest angle & the forward tooth to be at the least angle  It is designed to permit protrusive disclusion of thewww.indiandentalacademy.com
    • CURVE OF WILSON  Mediolateral curve that contacts the buccal & lingual cusp tips on each side of the teeth.  Alignment of posterior teeth to parallel the direction of loading from the internal pterygoid muscle results in curve of wilson  Results from inward inclination of lower posterior teeth & outward inclination of upper posterior teeth  The inward inclination of lower occlusal table is designed for direct access from the lingual, with no blockage by lower lingual cusps  The outward inclination of upper occlusal table provides access from the buccal for the food to be tossed directly onto occlusal table by the action of buccinator www.indiandentalacademy.com
    •  When the curve of wilson is made too flat, ease of masticatory function may be impaired because of increased activity required to get the food onto the occlusal table.  The design of lower posterior teeth moving downward before they shifting medially is made possible by the curve of wilson. www.indiandentalacademy.com
    • POSTERIOR OCCLUSION Posterior teeth (cusp characteristics):  For teeth to remain stable there must be certain barriers against their displacement. These barriers are provided by the vertical overlaps of the teeth (occluso-apically by the opposing teeth) and mesio-distally by the contact areas.  This is achieved by a Holding cusps/supporting cusps/stamp cusp/centric cusps Non-holding cusps/non-centric/non-supporting cusps www.indiandentalacademy.com
    • During fabrication of restorations it is important that supporting cusps do not contact the opposing teeth in manners that result in lateral deflection; rather contacts should be on smoothly concave fossae so that forces are directed approximately parallel to the long axis of the teeth. Supporting cusps : these cusps contact the opposing teeth along the central fossa occlusal line. For upper posterior teeth in normal occlusion, these supporting cusps are usually the lingual cusps occluding in opposing fossae while for lower posterior teeth, they are usually the buccal cusps. www.indiandentalacademy.com
    •  Non-supporting cusps /Guiding cusps: These cusps do not contact the tooth and are usually located in the embrasures or developmental grooves of opposing teeth  They have sharper cusp ridges and form a separation between the soft tissues and occlusal table. www.indiandentalacademy.com
    • Posterior Tooth Contacts :  In idealized occlusal designed for restorative dentistry, the posterior teeth should contact only in MI.  Forceful contact or collisions of individual posterior tooth cusps during chewing and clenching may lead to patient discomfort or damage to the teeth.  During chewing the working-side closures start from a lateral position and are directed medially to MI.  Test movements are used by dentists to assess the occlusal contacts on the working side; for convenience, these movements are started in MI and move laterally.  Thus the working-side test movement follows the same pathway as the working-side chewing closure but occurs in the opposite direction.www.indiandentalacademy.com
    •  The preferred occlusal relationship for restorative purposes is to limit the working-side contact to the canine teeth.  Tooth contact posterior to the canine on the working side may occur naturally in worn dentitions.  Multiple tooth contacts during lateral jaw movement are termed group function.  Group function occurs naturally in a worn dentition; however, group function can be a therapeutic goal when the bony support of the canine teeth is compromised by periodontal disease.  During chewing closures, the mandibular teeth on the nonworking side close from a medial and anterior position and approach MI by moving laterally and posteriorly.  Avoidance of contacts on the nonworking side is an important goal for restorative procedures on the molar teeth.www.indiandentalacademy.com
    • ROLE OF CONTACT AREAS  A break in continuity of the line of contact areas throws additional responsibility on the PDL & alveolar bone.  Creating a contact that is too broad, bucco-lingually or occluso-gingivally in addition to changing the tooth anatomy will change the anatomy of the inter dental col.  The broadened contact produces an inter-dental area that the patient is less able to clean i.e. increases the area susceptible to future decay.  Creating a contact that is too narrow bucco-lingually or occluso-gingivally leads to greater susceptibility for microbial plaque accumulation & predisposes to the periodontal and caries problems. www.indiandentalacademy.com
    •  All tooth crowns exhibit contours in the form of convexities and concavities which should be reproduced in a restoration.  The concavities occlusal to the height of contour, whether they occur on anterior or posterior teeth are involved in the occlusal static and dynamic relations as they determine the pathways for mandibular teeth into and out of centric occlusion.  Deficient or mislocated concavities will lead to premature contacts during mandibular movements, which could inhibit the physiologic capabilities of these movements.  Excessive concavities can invite extrusion, rotation or tilting of occluding cuspal elements into non-physiologic relations with opposing teeth. ROLE OF CONTOUR www.indiandentalacademy.com
    • A marginal ridge should always be formed in two planes bucco- lingually, meeting at a very obtuse angle. This feature is essential when an opposing functional cusp occludes with the marginal ridge. A marginal ridge with these specifications is essential for; 1. The balance of the teeth in the arch. 2. Prevention of food impaction proximally. 3. Protection of the periodontium. 4. Prevention of recurrent and contact decay. 5. For helping in efficient mastication. ROLE OF MARGINAL RIDGES www.indiandentalacademy.com
    • SIGNS OF INSTABILITY OF OCCLUSIION  Excessive wear  Hypermobility of one or more teeth  Migration of one or more teeth – Horizontal shifting Intrusion Supraeruption www.indiandentalacademy.com
    • REQUIREMENTS FOR EQILIBRIUM OF THE MASTICATORY SYTEM  Stable TMJ‟s even when loaded  Anterior guidance in harmony with functional movements of the mandible  Noninterference of posterior teeth in centric occlusion posterior disclusion when condyle leaves CR  All teeth in vertical harmony with the masticatory muscles  All teeth in horizontal harmony with the neutral zone www.indiandentalacademy.com
    • REQUIREMENTS FOR OCCLUSAL STABILITY  Stable stops on all teeth when the condyles are in centric relation  Anterior guidance in harmony with the border movement of the envelope of function  Disclusion of all posterior teeth in protrusive movements  Disclusion of all posterior teeth in nonworking side  Noninterference of all posterior teeth on working side, with either the lateral anterior guidance or the border movements of the condyle.  In lateral movements, supporting cusps preferably should have slight freedom in centric and occlude in a valley like space on opposing teeth (in grooves or embrasures), to facilitate non interfering passage of cusps.  During protrusive movements, there should not be any tooth contact posteriorly. www.indiandentalacademy.com
    • OCCLUSAL EQUILIBRATION  Reduction of all contacting tooth surfaces that interfere with the completely seated condylar position i.e., centric relation  Selective reduction of tooth structure that interferes with lateral excursions  Elimination of the posterior tooth structure that interferes with protrusive excursions.  Harmonization of the anterior guidance www.indiandentalacademy.com
    • VERIFICATION OF COMPLETION  Clench test : Clenching the tooth together & squeezing firmly. Reasons for discomfort : incomplete elimination of occlusal interferences on the posterior teeth www.indiandentalacademy.com
    • COMPUTER ASSISTED DYNAMIC OCCLUSALANALYSIS T – scan  Developed by Maness.  Sensor unit that records occlusal contacts on a thin mylar film & relays the information to a computer www.indiandentalacademy.com
    •  The occlusal contacts on teeth can be located by marking them with articulating paper or ribbon held by Miller‟s forceps.  Shim stock or Mylar strips are also helpful in identifying the presence of occlusal contacts. DENTITION – OCCLUSAL EXAMINATION www.indiandentalacademy.com
    • The examination of the occlusion is performed in three steps: 1. First, the teeth need to be dry and one of the easiest ways of doing this is to ask the patient to close onto folded tissue paper held by Miller forceps. 2. Mark-up the patient's dynamic occlusion, by asking the patient to slide his/her teeth from side-to-side whilst holding the articulating paper (Blue paper) between them. 3. The final stage requires changing the colour of the paper (Red) and asking the patient to tap his/her teeth' together into a normal bite. This will mark the static occlusion. www.indiandentalacademy.com
    •  Before initiating treatment the practitioner must decide whether to provide restorations within the existing occlusal scheme or to change it deliberately.  Conformative approach is defined as the provision of restorations „in harmony with the existing jaw relationships‟.  It is the principle of providing a new restoration that does not alter the patient‟s occlusion  Majority of restorations follow this principle.  “The provision of new restorations to a different occlusion which is defined before the work is started: i.e. „to visualize the end before starting‟ is defined as the re-organized approach.” TREATMENT PLANNING CONFORMATIVE APPROACH www.indiandentalacademy.com
    •  When considering the provision of simple restorative dentistry to the conformative approach, no matter what type of occlusal restoration is being provided the sequence is always the same - THE ‘EDEC PRINCIPLE’.  The EDEC Principle is useful in relation to: - Direct restorations - Indirect restorations TECHNIQUE www.indiandentalacademy.com
    • 1. Examine:  Examine the static and dynamic occlusions before picking up a handpiece.  Mark them pre operatively on teeth, as explained earlier.  Malpositioned opposing supporting cusps, ridges or fossae may be recontoured in order to achieve optimal occlusal contacts in the restored tooth.  Plunger cusps and over erupted teeth are to be reduced.  In anterior restorations, the scheme of incisal guidance must be examined and understood prior to tooth preparation.  Also, an assessment of periodontal condition must be made. THE EDEC PRINCIPLE FOR DIRECT RESTORATIONS www.indiandentalacademy.com
    • 2. Design:  Always visualize the design of the cavity preparation. This is better done after a simple occlusal examination .  The existing occlusal marks will either be preserved by being avoided in the preparation, or they will be involved in the design, but never end preparation margins at these points. 3. Execution:  The execution of the restoration must be to the design (form) of the preparation that the dentist will have decided before starting to cut.  Controlled interproximal cutting and care in restoring axial tooth contour to avoid overcontouring is essential.  Carving of restorations must be harmonious to occlusion and should not introduce premature contacts.www.indiandentalacademy.com
    • 4. Check:  Finally, check the occlusion of the restoration, that it does not prevent all the other teeth from touching in exactly the same way as they did before. This is either done by;  This is done by reversing the colour of the paper or foils used pre-operatively and using the preoperative marks as a reference. www.indiandentalacademy.com
    •  The dentist not only has to examine the occlusion in Indirect restorations but the results of that examination have to be accurately recorded and that record has to be transferred to the technician.  The EDEC principle followed for indirect restorations THE EDEC PRINCIPLE FOR INDIRECT RESTORATIONS www.indiandentalacademy.com
    • 1. Examine:  The examination of the patient‟s pre-existing occlusion is carried out in exactly the same way as described for the direct restoration.  There is a need for this information to be transferred accurately to the laboratory technician; hence a record must be made.  The methods of recording interocclusal records include:  Two dimensional bite records – Intra oral photographs, written records, and/or Occlusal Sketching  Three dimensional bite records – Bite registration materials such as hard wax, acrylic resin, elastomers etc  A combination of both. www.indiandentalacademy.com
    • 2. Design:  Clinically the cavity preparation is designed in exactly the same way as for a direct restoration.  The fundamental difference is that , the technician is going to make the restoration. 3. Execute:  From an occlusal point of view one of the most significant considerations is the provision of a temporary restoration which duplicates the patient's occlusion and is going to maintain it for the duration of the laboratory phase.  For this the temporary restoration should: be a good fit, so that it is not going to move on the tooth; provide the correct occlusion, so that the prepared tooth maintains its relationships; be in the same spatial relationship with adjacent and opposing teeth. www.indiandentalacademy.com
    • 4. Check:  The occlusion of the restoration should be as ideal as possible (preferably not on an incline) and should not prevent all the other teeth from touching in exactly the same way as they did before. This needs to be checked before and after cementation. www.indiandentalacademy.com
    •  Occlusion is fundamental to the practice of dentistry, in providing a biologically functional restoration and for comprehensive patient care.  A dental restoration after being attached to the tooth becomes one of the essential components of the stomatognathic system. Hence, any restoration (from intracoronal direct restoration to complex crown and bridge work) must be planned to conform to the existing occlusal pattern and not to disturb it CONCLUSION www.indiandentalacademy.com
    •  WHEELER‟S Dental Anatomy, Physiology & Occlusion 7th edition  PETER E. DAWSON Functional Occlusion  STURDEVANT‟S Art & Science of Operative Dentistry 5th edition  M.A. MARZOUK Operative Dentistry modern theory and practice  S J Davies et.al., - Occlusion: Good occlusal practice in simple restorative dentistry. British Dental Journal (2001) 191, 365 - 381 REFERENCES www.indiandentalacademy.com
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