INTRODUCTIONJAW RELATION is defined as any relation of themandible to maxilla.Jaw relation is recorded to measure the extensibilityand movements permissible by the patients TMJ.3 DIFFERENT TYPES:1. Orientation jaw relation2. Vertical jaw relation3. Horizontal jaw relation
HORIZONTAL JAW RELATIONHorizontal jaw relation is the maxillomandibularrelation in a horizontal plane.Described as relationship of mandible to maxilla inthe anteroposterior direction. 2 TYPES:1) CENTRIC jaw relation2) ECCENTRIC jaw relation
CENTRIC RELATIONDef :The maxillomandibular relationship in whichcondyles articulate with the thinnest avascularportion of their respective disc with the complex in theanterior superior position against the slopes ofarticular eminences.This position is independent of tooth contact.This position is discernible when the mandible is directedsuperiorly and anteriorly.It is restricted to a purely rotary movement about thetransverse horizontal axis.
3 primary requirements:1. To record the correct horizontal relationship ofmandible to maxilla2. To expert equalized vertical pressure3. To retain record in undistorted condition until thecast have been accurately mounted on articulator
SIGNIFICANCE: In case of dentulous patients proprioceptive impulsesare obtained from PDL. In case of edentulous patients centric relation act asproprioceptive centre to guide occlusal movements.
SALIENT FEATURES:o Is a definite learned positiono Patient can voluntarily and reflexily return to this position.o Can be recorded and repeated.o On mounting the cast on articulator he anteroposterior relation ofmaxillary and mandibular casts becomes a definite entity.o This position can be verified.o Is a reference point in recording maxillomandibular relations and astarting point for developing occlusion.
RETRUDING THE MANDIBLE:Mandible should be in the most posterior position while recording centricrelation.Method:Relax the patientTry to bring his upper jaw forward while occluding on the posterior teeth.Instruct the patient to touch the posterior border of the upper record basewith his tongue.Mandibular occlusal rim should be tapped with a finger gently.this wouldhelp patient automatically to retrude his mandible.
METHODS TO RECORD CENTRIC RELATION:PHYSIOLOGICALtactile or inter occlusal check record methodPressureless methodPressure methodFUNCTIONALNeedle house methodPatterson methodGRAPHICIntra oralExtra oralRADIOGRAPHIC METHOD
Physiologic methodBased on:o Proprioceptive impulse of patiento Kinethetic sense of mandibular movemento Visual acuity and sense of touch of patient1) Tactile sense or inter occlusal check record method.Tentative jaw relation is recorded.Ask the patient to retrude the mandible.Casts are articulated based on this tentative record
INDICATIONS Abnormally related jaws. Displaceable flabby tissue. Large tongue Uncontrolled mandibular movements. In patients already using a complete denture
PROCEDURE:a) Recording tentative jaw relation:) Maxillary occlusal rim inserted to patients mouth.) Vertical dimension at rest is established.mandibularocclusal rim inserted and reduced accordingly,) Tentative centric relation recorded using tentativejaw relations.artificial teeth are arranged.
b) Making the inter occlusal check record.Upper and lower trial dentures are inserted into themouth.keep a piece of cotton to prevent contact ofopposing members.Aluwax is added on the occlusal surface of teeth ofmandibular occlusal rimPatient asked to retrude mandible and close on the waxtill tooth contact occurs.Trial dentures removed and allowed to cool.
2)Static or pressureless method.Nick notch method:Patient asked to retrude mandible in position.Upto 3mm of wax removed from mandibular occlusalrimfrom the premolar region till the distal end1 or 2 notches are cut on the corresponding area of maxillaryocclusal rim.One nick is cut anterior to the notch,a V shaped valleyNick:prevent lateral movementNotch: anteroposterior movement
Nick and notch are lubricated with petroleum.Prepared occlusal rim are inserted into patient’s mouthand taught to close his mandible in maximum retrudedposition.Aluwax is placed on the trough created in mandibularrim.Mandibular occlusal rim is cooled and inserted intopatients mouth and closed in centric relation.
3)Pressure methodEstablish vertical dimension.Upper occlusal rim inserted.lower occlusal rim isfabricated by softening in water bath.Insert it into patients mouth.Patient asked to close mouth in centric relation on softwax in predetermined vertical dimension and thenarticulated.
Functional methodMethod utilise the the functional movements of jaws to record the centric relation.Patient asked to perfprm border border movements such as protrusive and lateralexcersion movement.a) Needle house method) Fabrication of occlusal rim made from impression compound) Four metal beads or styli are embedded into premolar and molar areas ofmaxillary occlusal rim.) Occlusal rim inserted into patients mouth and asked to close occlusal rim andmake protrussive,retrussive ,right and left movement of mandible.) When movements are made “diamond shaped marking pattern rather than a lineis formed on the mandibular occlusal rim.
Patient produces mandibular movements by movingmandible to protrusion , retrusion, right and leftlateral
b)Patterson methodOcclusal rim made of modelling wax.In trench or trough is made along the length ofmandibular occlusal rim.A mixture of carborundum and dental plaster is loadedinto the trench.Perform mandibular movement till predeterminedvertical dimension.Movement generates compensative curves in plaster
Graphic methodThe graphic method record a tracing of mandibularmovements in one plane2 types:1) Arrow point tracing2) PantographArrow point tracing is a graphic record measured across singleplanePantogaph is measured three dimensionally.
Factors to be considered while carrying outtracing1. Stability of denture base2. Resistance of rims3. Difficulty in placing central bearing device4. Height of residual alveolar ridge5. Tongue interferance6. Efficiency of recording device7. Lack of coordinated movements
Arrow point tracing or gothic arch tracer Made using gothic arch tracers Recorded in horizontal plane. Consists of central bearing device:a device that provide central point ofbearing or support between the maxillary & mandibular dental arches.consists of contacting point attached to one dental arch and plate attachedto opposing dental archPlate provide surface on which the tracing of mandibular movements isrecorded.Consists of:CENTRAL BEARING POINT & CENTRAL BEARING PLATE.
TYPES OF ARROW POINT TRACERS:1) INTRA ORAL TRACING POINT:) Central bearing device is located intra orally.) Tracer is placed within the mouth.) Central bearing point & plate is inserted into patients mouth.) Central bearing point is adjusted such that it contact the central bearingplate at predetermined vertical dimension.) Ask to make anteroposterior and lateral movements.) Central bearing point will draw the tracing pattern on central bearingplate) Tracing should resemble an arrow point with a sharp apex.
2)EXTRA ORAL POINT TRACER:Concept similar to intra oral tracer.Additionally have an attachment that project outside mouth.Record bases attached to recording devices inserted in patients mouth.Central bearing point is retracted to conduct training exercises.Recording plate which projects extra orally is coated with precipitatedchalk and denatured alcohol.Patient asked to perform all movements.Examine for sharp apex.
Points to be considered while doing graphictracing method1. Displacement of record base may result frompressure if central bearing points is off center whenmandible moves in eccentric relation to maxilla2. If central bearing device is not used the occlusalrims offer more resistance to horizontal movements3. Difficult to stabilize record base against horizontalforces on tissue that are pendulous
4. Difficult to stabilize record base against horizontalforces on residual ridges that have no vertical height5. Difficult to stabilize record base with pt who haveawkward tongues6. Recording device are not usually consideredcompactible with physiologic stimulation inmandibular movements7. Tracing is not accepted unless a pointed apex isdeveloped
8. Double tracing-lack of coordinated movement9. It is made at predetermined vertical dimension ofocclusion.this harmonius centric relation withcentric occlusion and anteroposterior bone –bonerelation with tooth-tooth contact10. Graphic method can reecord eccentric relation ofmandible to maxilla11. Most accurate means
Pantographic tracingA graphic record of mandibular movements in three planesas registered by styli on recordable tables of apantograph,tracing of mandibular movement recorded onplates in horizontal and sagittal planes.Make the rim contact at desired vertical relationship.Strips of celluloid paper are placed between the rim andpulled out.patient is asked to close and restrain the celluloidfrom slipping away,mandible goes to centric relation.Softened wax is placed on mandibular occlusal rim andpatient is asked to bite in centric relation.
ECCENTRIC JAW RELATION“any relationship of mandible to maxilla other thancentric relation”Include protrusive and lateral relations.Help to adjust the lateral and horizontal condylarinclination in the articulator.Thus helps the articulator to reproduce eccentricmovements of mandible and establish balancedocclusion.Recorded using functional or tactile method.
conclusionThe accurate determination , recording, and transferof jaw relation records from edentulous patient toarticulator is essential for restoring function, facialapperance, and maintainance of patients health.Un satisfactory maxillomandibular relations willeventually lead to failure of complete denture
Referances1. Essentials of complete denture prosthodontics 2ndedition: Sheldon Winkler2. Clinical dental prosthetics: H.R.B FENN: 2nd edition3. Syllabus of complete denture : Charles MHeartwell:4th edition4. Textbook of prosthodontics : Deepak Nallaswami