Horizontal Jaw Relation, Horizontal Jaw Relation, Methods Of Recording In Methods Of Recording In

ProsthodonticsProsthodontics

Date: 23Date: 23rdrd Feb,07 Feb,07

Presented by:- Gautam AdhikariPresented by:- Gautam Adhikari

Horizontal jaw relationHorizontal jaw relation

It is the relationship of the mandible to the It is the relationship of the mandible to the maxilla in a horizontal plane.maxilla in a horizontal plane.

It can also be described as the relationship It can also be described as the relationship of the mandible to the maxilla in the of the mandible to the maxilla in the antero-posterior direction.antero-posterior direction.

Horizontal jaw relation can be Horizontal jaw relation can be centriccentric or or eccentriceccentric jaw relations. jaw relations.

To maintain stability of complete dentures, To maintain stability of complete dentures, the opposing teeth must meet evenly on the opposing teeth must meet evenly on both sides of the dental arch when the both sides of the dental arch when the teeth contact anywhere within the normal teeth contact anywhere within the normal functional range of mandibular movement. functional range of mandibular movement.

An occlusion of complete dentures that An occlusion of complete dentures that provides these even contacts can be provides these even contacts can be developed only when developed only when centric occlusion is centric occlusion is in harmony with centric relation.in harmony with centric relation.

Centric Occlusion (CO):Centric Occlusion (CO):

Def. - “The occlusion of opposing teeth Def. - “The occlusion of opposing teeth when the mandible is in centric relation. when the mandible is in centric relation. This This may or may not coincide with the may or may not coincide with the maximal intercuspal positionmaximal intercuspal position”. ”.

(GPT 8(GPT 8thth ed.) ed.)

Centric Relation (CR):Centric Relation (CR):

““The maxillo-mandibular relationship in The maxillo-mandibular relationship in which the condyles articulate with the which the condyles articulate with the thinnest avascular portion of their thinnest avascular portion of their respective disks with the complex in the respective disks with the complex in the anterior-superior position against the anterior-superior position against the slopes of the articular eminences. This slopes of the articular eminences. This position is independent of tooth contact. position is independent of tooth contact. This position is clinically discernible when This position is clinically discernible when the mandible is directed superior and the mandible is directed superior and anteriorly. It is restricted to a purely rotary anteriorly. It is restricted to a purely rotary movement about the transverse horizontal movement about the transverse horizontal axis” (GPT 5axis” (GPT 5 thth ed.). ed.).

The most retruded physiological relation of The most retruded physiological relation of the mandible to the maxillae to and from the mandible to the maxillae to and from which the individual can make lateral which the individual can make lateral movement. It is a condition that can exit at movement. It is a condition that can exit at various degrees of jaw separation. It various degrees of jaw separation. It occurs around the terminal hinge axis. occurs around the terminal hinge axis.

(GPT-3)(GPT-3)

The most retruded relation of the mandible The most retruded relation of the mandible to the maxillae when the condyles are in to the maxillae when the condyles are in the most posterior unstrained position in the most posterior unstrained position in the glenoid fossae from which lateral the glenoid fossae from which lateral movement can be made at any given movement can be made at any given degree of jaw separation.degree of jaw separation.

(GPT-1)(GPT-1)

Centric relation is the most posterior Centric relation is the most posterior relation of the mandible relative to the relation of the mandible relative to the maxillae from which lateral movements maxillae from which lateral movements can be made at a given vertical dimension. can be made at a given vertical dimension. (Boucher)(Boucher)

A maxilla to mandible relationship in which the A maxilla to mandible relationship in which the condyles and disks are thought to be in the condyles and disks are thought to be in the midmost, uppermost position. The position has midmost, uppermost position. The position has been difficult to define anatomically but is been difficult to define anatomically but is determined clinically by assessing when the jaw determined clinically by assessing when the jaw can hinge on a fixed terminal axis (upto 25mm). It can hinge on a fixed terminal axis (upto 25mm). It is a clinically determined relationship of the is a clinically determined relationship of the mandible to the maxilla when the condyle disk mandible to the maxilla when the condyle disk assemblies are positioned in their most superior assemblies are positioned in their most superior position in the mandibular fossae and against the position in the mandibular fossae and against the distal slope of the articular eminence.distal slope of the articular eminence.

(Ash)(Ash)

The relation of the mandible to the maxillae The relation of the mandible to the maxillae when the condyles are in the uppermost and when the condyles are in the uppermost and rear most position in the glenoid fossae. This rear most position in the glenoid fossae. This position may not be able to be recorded in the position may not be able to be recorded in the presence of dysfunction of the masticatory presence of dysfunction of the masticatory function.function.

(Lang)(Lang)

A clinically-determined position of the mandible A clinically-determined position of the mandible placing both condyles into their anterior placing both condyles into their anterior uppermost position. This can be determined in uppermost position. This can be determined in patients without pain or derangement in the TMJpatients without pain or derangement in the TMJ

(Ramsfjord 1993)(Ramsfjord 1993)

The centric relation has the following The centric relation has the following features:features:

It is It is learnablelearnable, , repeatablerepeatable and and recordablerecordable position which remains constant throughout life.position which remains constant throughout life.

It is a definite learned position from which the It is a definite learned position from which the mandible can move to any eccentric position and mandible can move to any eccentric position and return back involuntarilyreturn back involuntarily. It acts as a centre from . It acts as a centre from which all movements can be made.which all movements can be made.

If the mandible has to move from one eccentric If the mandible has to move from one eccentric position to another it should go to the centric position to another it should go to the centric relation before advancing to the target eccentric relation before advancing to the target eccentric position. position.

Functional movements like chewing and Functional movements like chewing and swallowing are performed in this position, swallowing are performed in this position, because it is the most because it is the most unstrained position.unstrained position.The muscles that act on the The muscles that act on the temporo-temporo-mandibular joint are arranged in such a way mandibular joint are arranged in such a way that it is easy to move the mandible to the that it is easy to move the mandible to the centric position from where all movements centric position from where all movements can be made.can be made. The casts should be mounted in centric The casts should be mounted in centric relation because it is the relation because it is the point from which point from which all the movements can be made or all the movements can be made or simulated in the articulator. simulated in the articulator.

It is helpful in adjusting condylar guidance It is helpful in adjusting condylar guidance in an articulator in an articulator toto produce balanced produce balanced occlusion.occlusion.

It is It is definite entitydefinite entity, so it is used as a , so it is used as a reference point in establishing centric reference point in establishing centric occlusion.occlusion.

Harmony Between Centric Relation Harmony Between Centric Relation And Centric Occlusion:And Centric Occlusion:

““Centric” is an adjective and must be used Centric” is an adjective and must be used with either relation or occlusion to be with either relation or occlusion to be specific and meaningful.specific and meaningful.

Centric relation is a Centric relation is a bone-to-bone bone-to-bone relationshiprelationship whereas centric occlusion is a whereas centric occlusion is a relationship of relationship of upper and lower teeth to upper and lower teeth to each other.each other.

In many people, CO of the natural teeth In many people, CO of the natural teeth does not coincide CR of the jaws.does not coincide CR of the jaws.

In natural dentition CO is usually located In natural dentition CO is usually located 0.5 to 1 mm anterior to CR.0.5 to 1 mm anterior to CR.

Natural tooth interferences in CR initiated Natural tooth interferences in CR initiated impulses and responses that direct the impulses and responses that direct the mandible into CO. mandible into CO.

When natural teeth are removed many When natural teeth are removed many receptors that initiated impulses resulting receptors that initiated impulses resulting in positioning of the mandible are lost or in positioning of the mandible are lost or destroyed.destroyed.

Therefore, the edentulous patient cannot Therefore, the edentulous patient cannot control mandibular movements.control mandibular movements.

Deflective occlusal contacts in CR cause Deflective occlusal contacts in CR cause movement of the denture bases and movement of the denture bases and displacement of the supporting tissues or displacement of the supporting tissues or direct the mandible away from the relation.direct the mandible away from the relation.

Therefore, CR must be recorded for Therefore, CR must be recorded for edentulous patients to enable CO to be edentulous patients to enable CO to be established in harmony with it.established in harmony with it.

Form and function of TMJ Form and function of TMJ structures:structures:

Normal functional movement of TMJ Normal functional movement of TMJ entails apposition of the articular surfaces entails apposition of the articular surfaces of the condyle and eminence, with of the condyle and eminence, with consideration of the anatomy and position consideration of the anatomy and position of the interposed intra-articular tissues.of the interposed intra-articular tissues.

A description of centric relation must A description of centric relation must include the functional relationship of the include the functional relationship of the inter articular tissues to be clinically inter articular tissues to be clinically significant. significant.

Components of TMJ: Components of TMJ:

It consists of cranial base, the mandible It consists of cranial base, the mandible and the muscles of mastication with their and the muscles of mastication with their innervation and vascular supply.innervation and vascular supply.

An articular disc separates the mandibular An articular disc separates the mandibular fosse and the articular tubercle of the fosse and the articular tubercle of the temporal bone from the condylar process temporal bone from the condylar process of the mandible.of the mandible.

This soft tissue This soft tissue structure has 4 structure has 4 definable zones, the definable zones, the thinner central bearing thinner central bearing area and the thicker area and the thicker anterior and posterior anterior and posterior bands (disk) and bands (disk) and bilaminar zone (as it bilaminar zone (as it consists of 2 layers : consists of 2 layers : elastic superior layer elastic superior layer and a collagenous and a collagenous inelastic inferior layer). inelastic inferior layer).

Failure of the central bearing area of the Failure of the central bearing area of the intra-articular tissue to remain in intra-articular tissue to remain in apposition to the articular surfaces of the apposition to the articular surfaces of the condyle is associated with joint condyle is associated with joint abnormalities, including displacement, abnormalities, including displacement, clicking or locking and perforation of the clicking or locking and perforation of the disk.disk.

The central bearing area is composed of The central bearing area is composed of densely woven collagen fibrils having no densely woven collagen fibrils having no vascularity or innervation, while indicates vascularity or innervation, while indicates that this zone is adapted to accept that this zone is adapted to accept pressure.pressure.The posterior limit of movement of the The posterior limit of movement of the condyle on the eminence has been condyle on the eminence has been attributed to wedging of the thickened attributed to wedging of the thickened posterior band of the disk between the posterior band of the disk between the distal surface of the condyle and the roof distal surface of the condyle and the roof of the articular fossa.of the articular fossa.

The innervated posterior band possibly The innervated posterior band possibly protects by sensory feed back, the thin protects by sensory feed back, the thin roof of the articular fossa from heavy roof of the articular fossa from heavy pressure and provides a bio-mechanically pressure and provides a bio-mechanically stable relationship.stable relationship.

Muscle involvement in centric Muscle involvement in centric relation:relation:

Centric relation is not a resting or postural Centric relation is not a resting or postural position of mandibleposition of mandible

Contraction and relaxation of muscles is Contraction and relaxation of muscles is necessary to move and fix the mandible in it.necessary to move and fix the mandible in it.

Retrusion:Retrusion: Middle and posterior temporal fibres.Middle and posterior temporal fibres.

Suprehyoid muscles genio-hyoid and digastricSuprehyoid muscles genio-hyoid and digastric

Elevation: Elevation: Anterior temporal fibresAnterior temporal fibres

MasseterMasseterMedial pterygoidMedial pterygoid

Lateral and protrusive:Lateral and protrusive:Lateral pterygoidLateral pterygoid

Williamson studied the pattern of muscle Williamson studied the pattern of muscle contraction in centric.contraction in centric.

He found that the contraction of the He found that the contraction of the superior head of external pterygoid placed superior head of external pterygoid placed the disk in a braced position against the the disk in a braced position against the posterior slope of articular eminence and posterior slope of articular eminence and the contraction of temporalis positioned the contraction of temporalis positioned the condyle superiorly in closed the condyle superiorly in closed approximation to the articular disc.approximation to the articular disc.

This condyle disc assembly was then This condyle disc assembly was then finally seated against the posterior slope of finally seated against the posterior slope of the articular eminence by the contraction the articular eminence by the contraction of masseter and temporalis.of masseter and temporalis.

Retruding the mandible to CR: Retruding the mandible to CR:

The mandible should be in its most The mandible should be in its most posterior position while recording centric posterior position while recording centric relation. relation.

Some patients may show difficulties in Some patients may show difficulties in retruding the mandible due to certain retruding the mandible due to certain biologic, psychologic, and mechanical biologic, psychologic, and mechanical conditioncondition. .

Method of retruding the Method of retruding the mandiblemandible

Relaxing the patient. Making him feel Relaxing the patient. Making him feel comfortable.comfortable.

The patient is asked to try to bring his The patient is asked to try to bring his upper jaw forward while occlusing on the upper jaw forward while occlusing on the posterior teeth.posterior teeth.

The patient should be instructed to touch The patient should be instructed to touch the posterior border of the upper record the posterior border of the upper record base with his tongue. base with his tongue.

The mandible occlusal rim should be The mandible occlusal rim should be tapped gently with a finger. This would tapped gently with a finger. This would automatically make the patient to retrude automatically make the patient to retrude his mandible. his mandible.

The temporalis and the masseter are The temporalis and the masseter are palpated to relax them.palpated to relax them.

Difficulties in retruding Difficulties in retruding mandible:mandible:

Difficulties in retruding the mandible can be Difficulties in retruding the mandible can be classified as:classified as:

Biological Biological

PhysiologicalPhysiological

MechanicalMechanical

Biological causesBiological causes

Lack of coordination between groups of Lack of coordination between groups of opposing muscles when the patient is opposing muscles when the patient is requested to close in the retruded position.requested to close in the retruded position.

Habitual eccentric jaw relation.Habitual eccentric jaw relation.

Physiological causesPhysiological causes

Inability of the patient to follow the dentist’s Inability of the patient to follow the dentist’s instructions is one of the major instructions is one of the major psychophysiological factors, which produce psychophysiological factors, which produce difficulty in retruding the mandible. difficulty in retruding the mandible.

This is overcome by instituting stretch This is overcome by instituting stretch relax exercises, training the patient to relax exercises, training the patient to open and close his mouth. Central bearing open and close his mouth. Central bearing devices can also be used to retrude the devices can also be used to retrude the mandible in these patients.mandible in these patients.

Mechanical causesMechanical causes

Poorly fitting base plates produce difficulty Poorly fitting base plates produce difficulty in retruding the mandible. The base plates in retruding the mandible. The base plates should be checked using a mouth mirror should be checked using a mouth mirror for proper adaptation.for proper adaptation.

Methods Of Recording The Centric Methods Of Recording The Centric Jaw Relation:Jaw Relation:

According to Smith in 1941, Moylar in According to Smith in 1941, Moylar in 1955, and Kapur in 1957 following are the 1955, and Kapur in 1957 following are the methods for recording the centric relation:methods for recording the centric relation:

Direct recording,Direct recording,Graphic recording, Graphic recording, Functional recording and,Functional recording and,Cephalometrics recordingCephalometrics recording

Direct recording:Direct recording:

Oldest technique Oldest technique

CR recording can be recorded by following:CR recording can be recorded by following: Inter-occlusal check record methodInter-occlusal check record method Pressure-less methodPressure-less method Pressure methodPressure method Tripodal method (Akerly WB in 1979)Tripodal method (Akerly WB in 1979)

Inter-occlusal check record Inter-occlusal check record method:method:

Tentative jaw relationTentative jaw relation

The maxillary occlusal rim is inserted into the The maxillary occlusal rim is inserted into the patient’s mouth. patient’s mouth.

A tentative centric relation is recorded by using A tentative centric relation is recorded by using one of the methods to retrude the mandible.one of the methods to retrude the mandible.

The occlusal rims are articulated using the The occlusal rims are articulated using the tentative jaw relations and the artificial teeth are tentative jaw relations and the artificial teeth are arranged.arranged.

Now the trial dentures are ready for making the Now the trial dentures are ready for making the inter-occlusal check record. inter-occlusal check record.

Making the inter-occlusal check recordMaking the inter-occlusal check recordThe upper and lower trial dentures are The upper and lower trial dentures are inserted into the patient’s mouth.inserted into the patient’s mouth.The artificial teeth are prevented from The artificial teeth are prevented from contacting the opposing members by contacting the opposing members by keeping a piece of cotton inter-occlusally.keeping a piece of cotton inter-occlusally.Alu-wax is loaded on to the occlusal Alu-wax is loaded on to the occlusal surface of teeth in the mandibular occlusal surface of teeth in the mandibular occlusal rim. rim. The patient is asked to slowly retrude the The patient is asked to slowly retrude the mandible and close on the wax till tooth mandible and close on the wax till tooth contact occurs. contact occurs.

The trial dentures are removed and the wax is The trial dentures are removed and the wax is allowed to cool.allowed to cool.

Both the maxillary and mandibular trial dentures Both the maxillary and mandibular trial dentures are placed on their articulated casts. are placed on their articulated casts.

Before placing the trial dentures, the horizontal Before placing the trial dentures, the horizontal condylar guide locks in the articulator are condylar guide locks in the articulator are unlocked to allow free horizontal movement of the unlocked to allow free horizontal movement of the casts. casts.

The Aluwax on the buccal aspect of mandibular The Aluwax on the buccal aspect of mandibular teeth is scraped off and the articulated casts teeth is scraped off and the articulated casts (which are free to move horizontally) are adjusted (which are free to move horizontally) are adjusted to fit into the Aluwax check record.to fit into the Aluwax check record.

If the tentative relation record is accurate and is If the tentative relation record is accurate and is the same as the check record then both the the same as the check record then both the condylar elements of the articulator will contact condylar elements of the articulator will contact against the centric stops i.e. the articulated casts against the centric stops i.e. the articulated casts need not move to fit into the check records.need not move to fit into the check records.If anyone of the condylar elements (condylar If anyone of the condylar elements (condylar element represents the condyle in the element represents the condyle in the articulator) do not contact on the centric stops articulator) do not contact on the centric stops (centric stop represents the centric position of (centric stop represents the centric position of the condyle in the glenoid fossa) it indicates that the condyle in the glenoid fossa) it indicates that the tentative recording is inaccurate.the tentative recording is inaccurate.Occlusal indicator wax can be used instead of Occlusal indicator wax can be used instead of Aluwax for recording trial dentures with non-Aluwax for recording trial dentures with non-anatomical (cuspless) teeth.anatomical (cuspless) teeth.

If the tentative CR is accurate and same If the tentative CR is accurate and same as the check record then both the condylar as the check record then both the condylar elements of the articulator will contact elements of the articulator will contact against the centric stops against the centric stops

If any of the condylar elements do not If any of the condylar elements do not contact on the centric stops, it indicates contact on the centric stops, it indicates that the tentative record is inaccurate. that the tentative record is inaccurate.

Pressure-less method:Pressure-less method:

Occlusal rims are inserted.Occlusal rims are inserted.

Patient is trained to close the mouth at Patient is trained to close the mouth at centric relation positioncentric relation position

After attaining the centric relation, rims are After attaining the centric relation, rims are sealed.sealed.

Nick and notch method or stapler pin can Nick and notch method or stapler pin can be used to seal the rims. be used to seal the rims.

Nick and notch method:Nick and notch method:Patient is seated in a upright position, as it Patient is seated in a upright position, as it is easier to retrude the mandible in CR.is easier to retrude the mandible in CR.

Upto 3 mm wax is removed from the Upto 3 mm wax is removed from the mandibular rims, known as mandibular rims, known as ‘tough’‘tough’ (from (from premolar region till the distal end)premolar region till the distal end)

‘‘v’ shaped notches are cut from the v’ shaped notches are cut from the maxillary rim, running totally across the maxillary rim, running totally across the width of the occlusal rimwidth of the occlusal rim

‘‘V’ shaped nick from the maxillary rims is V’ shaped nick from the maxillary rims is cut anterior to the notch, but do not extend cut anterior to the notch, but do not extend throughout the width of the rims throughout the width of the rims

Nick and notch on the upper rim Nick and notch on the upper rim lubricated.lubricated.

Both he rims are inserted in the mouth and Both he rims are inserted in the mouth and patient is taught to close his mouth at the patient is taught to close his mouth at the maximum retruded position.maximum retruded position.

Mandibular rim is removed from the Mandibular rim is removed from the mouth.mouth.

Alu wax is placed on the troughs, 1.5 mm Alu wax is placed on the troughs, 1.5 mm of wax is projected above the rim.of wax is projected above the rim.

Then the rim is placed in the mouth and Then the rim is placed in the mouth and ask patient to close the mouth in CR.ask patient to close the mouth in CR.

Pressure method:Pressure method:

Here, after establishing the vertical Here, after establishing the vertical dimension, the upper occlusal rim is dimension, the upper occlusal rim is inserted into the patient’s mouth. inserted into the patient’s mouth. The lower occlusal rim if fabricated to be The lower occlusal rim if fabricated to be of excess height. of excess height. The entire lower occlusal rim is softened in The entire lower occlusal rim is softened in a water bath and inserted carefully into the a water bath and inserted carefully into the patient’s mouth.patient’s mouth.The patient is guided to close his mouth in The patient is guided to close his mouth in centric relation. centric relation.

The dentist should gently guide the The dentist should gently guide the mandible. The patient is asked to close on mandible. The patient is asked to close on the soft wax.the soft wax.

After the patient closes his mouth till the After the patient closes his mouth till the predetermined vertical dimension, both the predetermined vertical dimension, both the occlusal rims are removed, cooled and occlusal rims are removed, cooled and articulated.articulated.

Tripodal method:Tripodal method:

Tripodal is a direct method of recording Tripodal is a direct method of recording centric relation.centric relation.

The advantages are:The advantages are:

It offers a stable relationship with minimum It offers a stable relationship with minimum contact and maximum visibilitycontact and maximum visibility

Registration is made with minimum Registration is made with minimum pressurepressure

Registration is instantaneous Registration is instantaneous

Registration can be quickly and accurately Registration can be quickly and accurately verifiedverified

Patient’s habitual pattern of occlusion can Patient’s habitual pattern of occlusion can be recorded and compared with centric be recorded and compared with centric relation before posterior teeth are selected relation before posterior teeth are selected or arrangedor arranged

Method:-Method:-Fabricate rigid and stabilized record basesFabricate rigid and stabilized record bases

Construct maxillary rim to average Construct maxillary rim to average dimensiondimension

Construct the mandibular rim in 3 widely Construct the mandibular rim in 3 widely separated segments, 1 anterior and 2 separated segments, 1 anterior and 2 posterior segmentsposterior segments

Contour the maxillary occlusal rim for Contour the maxillary occlusal rim for esthetics and locate the occlusal planeesthetics and locate the occlusal plane

Establish the V.D of occlusionEstablish the V.D of occlusion

Determine intra orally the most desirable Determine intra orally the most desirable location for the registration tacks. The location for the registration tacks. The tacks should be widely separated to tacks should be widely separated to provide stability. They should be directed provide stability. They should be directed toward the maxillary rim. Mark the wax to toward the maxillary rim. Mark the wax to indicate the optimum linguo-facial and indicate the optimum linguo-facial and antero-posterior positions for the tacks antero-posterior positions for the tacks Make the face bow registration and mount Make the face bow registration and mount the maxillary cast on the articulator.the maxillary cast on the articulator.

Trim the mandibular rim according to the Trim the mandibular rim according to the marks to provide the best visibility and marks to provide the best visibility and remove excess wax to facilitate placement remove excess wax to facilitate placement of the tacksof the tacksPick up a metal tack with a forceps and Pick up a metal tack with a forceps and heat it on flame.heat it on flame.Press the hot tack into the wax. Locate the Press the hot tack into the wax. Locate the apex of the point 0.5 mm above the wax apex of the point 0.5 mm above the wax rim to allow for a 0.5 mm depression into rim to allow for a 0.5 mm depression into the maxillary rim at the vertical dimension the maxillary rim at the vertical dimension of occlusion. of occlusion.

Trim the wax away from each tack to Trim the wax away from each tack to provide better visibility.provide better visibility.

Recline the dental chair approx. 45Recline the dental chair approx. 4500

Stabilize the record base lightly on the Stabilize the record base lightly on the mandibular residual ridge with the index mandibular residual ridge with the index fingers on the record base and thumbs on fingers on the record base and thumbs on the inferior border of the mandible. the inferior border of the mandible.

Guide the closure of the patient’s jaw in Guide the closure of the patient’s jaw in centric relation to the 1centric relation to the 1stst contact of one or contact of one or more tacksmore tacks

Trim or add wax to provide simultaneous Trim or add wax to provide simultaneous contact of the 3 tracks at the desired contact of the 3 tracks at the desired vertical dimension of occlusion. The depth vertical dimension of occlusion. The depth of acceptable registrations should be 0.5 of acceptable registrations should be 0.5 mm at the apex of the indentation.mm at the apex of the indentation.

Soften the hard wax with a hot spatula in Soften the hard wax with a hot spatula in the 3 registration areas.the 3 registration areas.

While the wax is congealing, seat the maxillary While the wax is congealing, seat the maxillary record base with firm pressure and guide the record base with firm pressure and guide the mandible into centric relation closuremandible into centric relation closure

Chill the wax rim, color the indentation with a Chill the wax rim, color the indentation with a fine tipped marker. Trim the wax until only the fine tipped marker. Trim the wax until only the apex of indentation is visibleapex of indentation is visible

Confirm the accuracy of the C.R record by Confirm the accuracy of the C.R record by observing the relationship of tacks to the marks observing the relationship of tacks to the marks when the jaw is closed just short of contact in when the jaw is closed just short of contact in C.R. a registration is inaccurate if a vertical or C.R. a registration is inaccurate if a vertical or horizontal discrepancy is observed between the horizontal discrepancy is observed between the apex of any tack and the colored indentation. apex of any tack and the colored indentation.

Detach the maxillary cast and mounting Detach the maxillary cast and mounting from the articulator and place the record from the articulator and place the record bases on the casts. Chill the hard wax in bases on the casts. Chill the hard wax in cold watercold waterRelate the casts by seating the apices of Relate the casts by seating the apices of the tacks into the marked indentation the tacks into the marked indentation without pressure. The posterior part of the without pressure. The posterior part of the casts may need to be trimmed to prevent casts may need to be trimmed to prevent interference.interference.Repeat the registration procedure to Repeat the registration procedure to confirm the accuracy of the registration and confirm the accuracy of the registration and mounting. mounting.

Invert the articulator and note Invert the articulator and note discrepancies between the tacks and discrepancies between the tacks and indentations. If 2 or more identical indentations. If 2 or more identical discrepancies are noted the mandibular discrepancies are noted the mandibular cast is separated and remounted.cast is separated and remounted.

Make additional registrations as necessary Make additional registrations as necessary to verify the accuracy of the mounting or to verify the accuracy of the mounting or registrationregistration

Graphic technique:Graphic technique:

Hesse (1897) first needle point tracing Hesse (1897) first needle point tracing done and introduced the graphic method done and introduced the graphic method of recording centric relation.of recording centric relation.

Gysi (1910) improved and popularized this Gysi (1910) improved and popularized this method. method.

These methods are called so because These methods are called so because they use graphs or tracings to record the they use graphs or tracings to record the centric jaw relation. centric jaw relation.

Graphic methods are of two types namely: Graphic methods are of two types namely: Arrow point tracing and Arrow point tracing and

Pantograph. Pantograph.

Arrow point tracing:Arrow point tracing:

One dimensional graphic tracing made using One dimensional graphic tracing made using gothic arch tracers.gothic arch tracers.

General concept of this technique is that General concept of this technique is that a pen like a pen like pointerpointer is attached to one occlusal rim and is attached to one occlusal rim and a a recording plate recording plate is placed on the other rim.is placed on the other rim.

When the mandible moves, the pointer draws When the mandible moves, the pointer draws characteristic patterns on the recording plate.characteristic patterns on the recording plate.

The pointer is known as the central bearing point The pointer is known as the central bearing point and the recording plate is known as the central and the recording plate is known as the central bearing plate.bearing plate.

Functions of central bearing Functions of central bearing device:device:

Maintains VDMaintains VD

Equalizes the pressure by distributing the Equalizes the pressure by distributing the forces throughout the supporting tissues.forces throughout the supporting tissues.

Allows the mandibular movement to be Allows the mandibular movement to be dictated by the condyles. dictated by the condyles.

Indications of graphic method:Indications of graphic method:

Well healed broad edentulous sides.Well healed broad edentulous sides.

Adequate inter arch spaceAdequate inter arch space

In patients with habitual centric; the use of In patients with habitual centric; the use of the graphic method, allow the patient to the graphic method, allow the patient to record his true centric. record his true centric.

ContraindicationsContraindications::

Severely resorbed ridges.Severely resorbed ridges.

Excessively flabby ridges.Excessively flabby ridges.

Decreased arch space Decreased arch space difficult to place difficult to place central bearing device without raising the central bearing device without raising the VD.VD.

In patient with temporomandibular joint In patient with temporomandibular joint arthropathy.arthropathy.

In patient with abnormal jaw relations. In patient with abnormal jaw relations.

Technique:Technique:

Make a accurate stable maxillary and Make a accurate stable maxillary and mandibular record base, with contoured mandibular record base, with contoured wax occlusal rims.wax occlusal rims.

Establish the vertical dimension of jaw Establish the vertical dimension of jaw separation, with mandible at physiologic separation, with mandible at physiologic restrest

Reduce the mandibular occlusal rim to Reduce the mandibular occlusal rim to provide excessive interocclusal distanceprovide excessive interocclusal distance

Make a facebow transfer and mount the Make a facebow transfer and mount the maxillary cast.maxillary cast.

Make a tentative CR record at a Make a tentative CR record at a predetermined vertical dimension of predetermined vertical dimension of occlusion occlusion

Adjust the articulator with condylar Adjust the articulator with condylar elements secured against the centric stopselements secured against the centric stops

Relate the maxillary occlusal rim in the soft Relate the maxillary occlusal rim in the soft wax record and attached the mandibular wax record and attached the mandibular cast to the articulator with plastercast to the articulator with plaster

Mount the central bearing device. Care Mount the central bearing device. Care has to be taken to centre the central has to be taken to centre the central bearing point in relation to the plate both bearing point in relation to the plate both antero-posteriorly and laterallyantero-posteriorly and laterallyMount the tracing device. Mount the tracing device.

The stylus is attached to the The stylus is attached to the maxillary rim and recording maxillary rim and recording plate to the mandibular rimplate to the mandibular rim

This arrangement develops This arrangement develops an arrow point tracing with apex anteriorly. an arrow point tracing with apex anteriorly.

The reverse placement develops arrow The reverse placement develops arrow point tracing with apex posteriorly.point tracing with apex posteriorly.

Seat the record bases with the recording Seat the record bases with the recording device in the patients mouth. The record device in the patients mouth. The record base should be checked for stability and also base should be checked for stability and also any interferences between the occlusal rims any interferences between the occlusal rims when mandible is movedwhen mandible is movedThe stylus should maintain contact with the The stylus should maintain contact with the recording plate during mandibular movementrecording plate during mandibular movementRetract the stylus and the patient is Retract the stylus and the patient is conducted for training exercise to move the conducted for training exercise to move the mandible right left, forward and backward. A mandible right left, forward and backward. A Ney excursion guide can be used to aid in Ney excursion guide can be used to aid in training the patient.training the patient.

Home is the most retrudedComfortable position

position.

NEY excursion guide

When patient learn’s the mandibular When patient learn’s the mandibular movements, the tracing is made by droping the movements, the tracing is made by droping the stylus on the record plate. Before this the tracing stylus on the record plate. Before this the tracing plate is prepared for tracing by the thin coat of plate is prepared for tracing by the thin coat of chalk in denatured alcohol.chalk in denatured alcohol.When a definite arrow point tracing with a sharp When a definite arrow point tracing with a sharp apex is made, have the patient retrude the apex is made, have the patient retrude the mandible to centric relation. The point of the mandible to centric relation. The point of the stylus should be at the point of the apex of the stylus should be at the point of the apex of the arrow point tracing. Inject quick setting dental arrow point tracing. Inject quick setting dental plaster between the occlusion rims and allow the plaster between the occlusion rims and allow the plaster to harden.plaster to harden.

Remove the assembly Remove the assembly and mount the and mount the mandibular cast with mandibular cast with the new record.the new record.This record is a This record is a tentative record and will tentative record and will be checked with an be checked with an inter-occlusal check inter-occlusal check record when the teeth record when the teeth are arranged and the are arranged and the wax is countoured. wax is countoured.

Based on the location of the tracers, arrow Based on the location of the tracers, arrow point tracers can be classified as:point tracers can be classified as:

intra oralintra oral extra oral extra oral

Intra-oralIntra-oral Extra-oralExtra-oral

1.1.

2.2.

3.3.

4.4.

Tracing not visible when being Tracing not visible when being made.made.

Tracings are small as they are Tracings are small as they are located close to the centre of located close to the centre of rotation. Therefore difficult to rotation. Therefore difficult to locate the apex.locate the apex.

More accurate than extra oral as More accurate than extra oral as it is made closer to the center of it is made closer to the center of rotation of the condyle.rotation of the condyle.

Plate and styles not hindered by Plate and styles not hindered by the position of lips and cheeks.the position of lips and cheeks.

Visible when the tracing is being Visible when the tracing is being

mademade

Larger tracings easier to locate Larger tracings easier to locate

the apex.the apex.

Less accurate than intra oral as Less accurate than intra oral as

made further away from the made further away from the

center of rotation.center of rotation.

The lips and cheek interfere with The lips and cheek interfere with

the position of the plate and the the position of the plate and the

styles. styles.

5.5.

6.6.

7.7.

Lips and cheeks in passive Lips and cheeks in passive relation.relation.

Accuracy of the record cannot Accuracy of the record cannot be assessed as the record be assessed as the record bases may shift during the bases may shift during the recording.recording.

Example: Example:

Seidal tracerSeidal tracer

Ballard tracerBallard tracer

Messermar tracerMessermar tracer

Cobble tracerCobble tracer

Does not keep the lipsDoes not keep the lips

and cheek in passive relation.and cheek in passive relation.

Accuracy can be assessed Accuracy can be assessed

virtually.virtually.

Example:Example:

Hight tracing deviceHight tracing device

Stansberry tracersStansberry tracers

Philips extra-oral tracerPhilips extra-oral tracer

Sears trivet Sears trivet

Pantographic tracing:Pantographic tracing:

It is defined as, “A graphic record of It is defined as, “A graphic record of mandibular movement usually recorded in mandibular movement usually recorded in the horizontal, sagittal and frontal planes the horizontal, sagittal and frontal planes as registered by the styli on the recording as registered by the styli on the recording tables of a pantograph or by means of tables of a pantograph or by means of electronic sensors electronic sensors

(GPT- 8(GPT- 8thth ed) ed)

Pantographic tracer

It is a three-dimensional graphic tracer.It is a three-dimensional graphic tracer.

It is the most accurate method available It is the most accurate method available to record centric jaw relation. to record centric jaw relation.

Even eccentric jaw relation can be Even eccentric jaw relation can be recorded using these instruments. recorded using these instruments.

These equipments are very sophisticated These equipments are very sophisticated and are generally used in for full-mouth and are generally used in for full-mouth rehabilitation of dentulous patients. rehabilitation of dentulous patients.

A pantographic tracer has six flags:A pantographic tracer has six flags:Two flags located perpendicular to one Two flags located perpendicular to one another near the condyles. Totally there another near the condyles. Totally there are four flags adjacent to the right and left are four flags adjacent to the right and left condylar guidances. They locate the true condylar guidances. They locate the true hinge axis.hinge axis.

Two flags are placed in Two flags are placed in

the anterior region. They the anterior region. They

record the anteroposterior record the anteroposterior

movements. movements.

Functional technique:Functional technique:

The records in the functional class include The records in the functional class include the various chew-in techniques suggested the various chew-in techniques suggested by Needles, House, and Essig and by Needles, House, and Essig and Paterson. Paterson. They also include methods that make use They also include methods that make use of of swallowing for positioning and recording swallowing for positioning and recording the relative position of the jaws. the relative position of the jaws. The patient produces a pattern of The patient produces a pattern of mandibular movements by moving the mandibular movements by moving the mandible to protrusion, retrusion, and right mandible to protrusion, retrusion, and right and left lateral.and left lateral.

The following factors are common to all The following factors are common to all functional methods:functional methods:

In a functional method, a tentative centric In a functional method, a tentative centric relation and vertical dimension are relation and vertical dimension are measured for determining an accurate measured for determining an accurate centric relation.centric relation.The occlusal rims for these methods are The occlusal rims for these methods are reduced in excess than that required for reduced in excess than that required for the tentative vertical dimension.the tentative vertical dimension.The exact vertical dimension of occlusion The exact vertical dimension of occlusion is determined only when the patient closes is determined only when the patient closes on the occlusal rims and their attachments on the occlusal rims and their attachments (tracers etc).(tracers etc).

The record bases should be very stable The record bases should be very stable while recording centric jaw relation. If the while recording centric jaw relation. If the record base gets displaced, the mandible record base gets displaced, the mandible will tend to move into an eccentric will tend to move into an eccentric position.position.

Lack of equalized pressure exerted on the Lack of equalized pressure exerted on the record base can result in inaccuracies in record base can result in inaccuracies in recording centric jaw relation.recording centric jaw relation.

A good neuromuscular coordination is A good neuromuscular coordination is required form the patient. required form the patient.

Needles-House method:Needles-House method:

In 1918 Needle and House gave this In 1918 Needle and House gave this method.method.

In this method, compound occlusion rims In this method, compound occlusion rims with four metal styli placed in the maxillary with four metal styli placed in the maxillary rim. When the mandible moves with the rim. When the mandible moves with the styli contacting the mandibular rim, the styli contacting the mandibular rim, the styli cut four diamond shaped tracings. styli cut four diamond shaped tracings.

Maxillary rims with metal styli

Mandibular rims with diamond shaped markings

Patterson method: Patterson method:

In 1923, Patterson uses wax occlusion In 1923, Patterson uses wax occlusion rims. rims.

A trench is made in the mandibular rim A trench is made in the mandibular rim and a mixture of half plaster and half and a mixture of half plaster and half carborundum paste is placed in the trench. carborundum paste is placed in the trench.

The mandibular movements generate The mandibular movements generate compensating curves in the plaster and compensating curves in the plaster and carborundum. carborundum.

When the plaster and carborundum are When the plaster and carborundum are reduced to the predetermined vertical reduced to the predetermined vertical dimension of occlusion, the patient is dimension of occlusion, the patient is instructed to retrude the mandible and the instructed to retrude the mandible and the occlusion rims are joined together with occlusion rims are joined together with metal staples. metal staples.

Trench Carborundum and dentalplaster mixture

Lateral and retruding mandibular movement

Cephalometrics technique: Cephalometrics technique:

Pyott and Schoeffer in 1952 describes the Pyott and Schoeffer in 1952 describes the use of cephalometrics to record centric use of cephalometrics to record centric relation.relation.

Cephalometrics radiographs determined Cephalometrics radiographs determined the proper centric relation and vertical the proper centric relation and vertical dimension of occlusion.dimension of occlusion.

Other methods of Other methods of recording:recording:

M Bissasu in 1999M Bissasu in 1999 describes a simple describes a simple procedure that enables the edentulous procedure that enables the edentulous patient to put the tip of the tongue in the most patient to put the tip of the tongue in the most superior posterior position in the mouth.superior posterior position in the mouth.

Procedure:Procedure:A strip of rectangular shapedA strip of rectangular shaped

baseplate wax (50mm long baseplate wax (50mm long

and 17mm wide) adapted and 17mm wide) adapted

to the palatal surface of theto the palatal surface of the

maxillary record base.maxillary record base.

Cut 4 holes (10mm diameter)Cut 4 holes (10mm diameter)

Then holding the record base in the hand Then holding the record base in the hand demonstrate the patient where they should demonstrate the patient where they should place their tongue by placing an index place their tongue by placing an index finger into the holes.finger into the holes.

Then place the record base in the mouth Then place the record base in the mouth and assist the patient to put the tip of the and assist the patient to put the tip of the tongue into the first hole, then move it into tongue into the first hole, then move it into the second and so on, until it reaches the the second and so on, until it reaches the desired posterior position.desired posterior position.

Complications In Complications In Recording Centric Recording Centric

Relation: Relation:

Yurkstas and kapur (1964) concluded following Yurkstas and kapur (1964) concluded following factors influencing centric relation recordfactors influencing centric relation record::

Resiliency of the supporting tissuesResiliency of the supporting tissues

Stability of the recording basesStability of the recording bases

TMJ and its associated neuromuscular TMJ and its associated neuromuscular mechanismsmechanisms

Character of the pressure applied in making Character of the pressure applied in making the recordingthe recording

Technique used in making the recording and Technique used in making the recording and the associated recording devices usedthe associated recording devices used

Skill of the dentistSkill of the dentist

Health and cooperation of the patientHealth and cooperation of the patient

Posture of the patientPosture of the patient

Character or size of the residual alveolar Character or size of the residual alveolar archarch

Amount and character of the salivaAmount and character of the saliva

Size and position of the tongueSize and position of the tongue

Significance of centric relation:Significance of centric relation:

The correct registration of C.R is essential The correct registration of C.R is essential in construction of complete dentures:in construction of complete dentures:C.R serve as reference relation for C.R serve as reference relation for establishing an occlusion.establishing an occlusion.If C.R and C.O does not coincide in If C.R and C.O does not coincide in artificial teeth the stability of denture bases artificial teeth the stability of denture bases is jeopardized and the edentulous patients is jeopardized and the edentulous patients are subjected to unnecessary pain or are subjected to unnecessary pain or discomfort. So, C.R and C.O should discomfort. So, C.R and C.O should coincide coincide

C.R is used in edentulous patients for C.R is used in edentulous patients for closures during mastication and closures during mastication and swallowing.swallowing.C.R must be accurately recorded and C.R must be accurately recorded and transferred to the articulator to permit transferred to the articulator to permit proper adjustment of the condylar proper adjustment of the condylar guidance for the control of eccentric guidance for the control of eccentric movements of the instrumentmovements of the instrumentAn accurate C.R record properly orients An accurate C.R record properly orients the lower cast to the opening axis of the the lower cast to the opening axis of the articulator and orients the C.R to the hinge articulator and orients the C.R to the hinge axis of the articulator and the mandible. axis of the articulator and the mandible.