Slide 1

Horizontal jaw relationsVinay PavanKumar . K1st year MDS studentDepartment of ProsthodonticsAECS Maaruti Dental College

Horizontal jaw relationCentric relationClinical protocolEccentric relationProtrusive Lateral TheoriesMethods of recordingFunctional Physiological Graphic

Jaw RelationIt is described as any spatial relationship of the mandible to the maxilla

Horizontal jaw relation

Horizontal Jaw relation is the relationship of the mandible to the maxilla in a horizontal plane or it is the relationship of the mandible to the maxilla in an antero-posterior direction.

Centric relation

Eccentric relation

Protrusive relationLateral relationLeft lateral Right lateral

It can be of two types

Centric relation

The most retruded relation of the mandible to the maxilla when the condyles are in the most posterior unrestrained position in the glenoid fossa from which lateral movements can be made, at any given degree of jaw separation.

GPT-8

A maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anteriorsuperior position against the slopes of the articular eminences. This position is independent of tooth contact. This position is clinically discernible when the mandible is directed superiorly and anteriorly and restricted to a purely rotary movement about a transverse horizontal axis.

Purpose of recording centric relationIt is a bone to bone relation and it is constant

It is repeatable and recordable and thus serves as a reliable guide for developing centric occlusion in complete dentures

It is related to the terminal hinge axis ,in CR condyles exhibit pure rotation without any translation

Functional movements like chewing and swallowing can be carried out since it is the most unstrained position. Final act of masticatory stroke ends in centric relation

Reference relation

It is more definite than vertical relation since it is independent of tooth contact

Criterias for mandible to be in centric

Disk properly aligned on both condylesCondyle-disk assembly at the highest point against the posterior slopes of eminentiaMedial pole of condyle-disk assembly braced by bone

Theories of centric relation

The Muscle theory

The Ligament theory

The Osteofiber theory

The Meniscus theory

Saizer P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent 1971;26(6):581-91.

The Muscle theoryDefense reflex

External pterygoid muscles contracts

Halts the jaw

The Ligament theoryBind the elements of the articulation

Lateral radiographic views

Suspended or Floating condyle

Anatomic arrangement- not well suited to halt retrusive movement

The Osteofiber theoryMeyer

Fibrous stop - buffer

Retroarticular cushion

retrusive terminal stop

The Meniscus theoryThe posterosuperior surface unfolds along the roof of the glenoid fossaDiscs with their retromeniscal fibrous tissues--stop the retrusive condylar movements

Factors influencing centric relation recordsThe resiliency of the supporting tissues

Fit of the denture bases

Residual alveolar arch

Saliva

Tongue

Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. J Prosthet Dent 2005;93:305-10.

The health and cooperation of the patient

The posture of the patient

The temporomandibular joint and its associated neuromuscular mechanisms

The skill of the dentist

Pressure applied in making the recording

The technique used and the recording devices used

Difficulties in obtaining mandibular retrusion

Biologic difficulties

Mechanical difficulties

Psychological difficulties

Methods of assisting the patient to retrude the mandibleLet the jaw relax, pull it back and close slowly on the posterior teeth

Push the upper jaw out and close on the back teeth

Protrude and retrude the mandible repeatedly

Roll the tongue backwards towards the posterior border of upper denture and close the rims until they meetBissasu M. Use of the tongue for recording centric relation for edentulous patients. J Prosthet Dent 1999;82:369-70.

Boos stretch-relax exercises

Tilting the head backwards

Swallow and close

Recording the Centric relation

Primary requirements -

accuracyequalized vertical pressurerecording medium - uniform consistencyretain the record in an undistorted condition

Pressure used while recording the centric relation

Minimum closing pressure Opposing teeth to touch uniformly and simultaneously at their first contact

Heavy closing pressure To produce same displacement of the soft tissues as on the dentures during function

Methods used for recording centric relationTactile or interocclusal check record method

Functional (chew-in) methodsMeyers methodPattersons methodNeedles-House method

Excursive (graphic) methodsIntraoral tracing Extraoral tracing

Terminal hinge axis method

Other methodsDeglutitionPantography

Tactile or interocclusal check record methodPhilip Pfaff biscuit bitePatients proprioception and tactile sense

Indications:abnormally related jawsexcessively displaceable supporting tissues large tongueabnormal mandibular movementsverify occlusion in existing dentures

Interocclusal check record can be made-Between upper and lower rims

Between upper and lower artificial or natural teeth

Between a central bearing plate and pin

Bite registration/recording materials

WaxesQuick setting plasterImpression compoundBite registration paste (ZnO-E)Bite registration silicone

Technique Two steps-

Tentative records using occlusion rims

Interocclusal check records with the teeth arranged for try-in

Anterior try-inPosterior try-in

Seat the patient with head upright

31Soft tissue position affected by posture.

Nick and Notch method

Too shallow2 mm

Bite registration material

Recording centric relation

Mounting of the casts

Stapler pin method

Functional (chew-in) methodsMeyers methodPattersons methodNeedles-House method

Meyers method

Soft wax - generated pathPlaster index - set the teeth

Pattersons method

Wax occlusal rimsMixture of half plaster and half carborundum in the trenchCompensatory curve

Needles-House method

Compound occlusion rims Four metal styli

Diamond-shaped tracings

Excursive (graphic) methodsGothic arch tracingArrow point tracing

Tracing in one planeApex - the most retruded position

Uses-Verify centric relationObtain protrusive and lateral records

Types-

Intraoral tracerExtraoral tracer

Intraoral tracing assembly

Intraoral tracing

Extraoral tracing (Hight tracing device)

Extraoral tracing

Types of arrow point tracingsTypical

Flat

Asymmetric

Absent apex

Miniature tracing

Double arrow point

Dorsally extended arrow point

Interrupted form

Atypical form

Terminal hinge axis methodAn imaginary line around which the mandible may rotate without translatory movement.

In pure hinge movement49

Other methods-Deglutition PantographyDeglutition

Physiologic methodswallow and hold

Physiologic Centric Relation (Shanahan)Swallow and hold

Shanahan TEJ. Physiologic jaw relations and occlusion of complete dentures. J Prosthet Dent 2004;91(3):203-05.

Verification after denture fabrication30-gauge wax

Shanahan TEJ. Physiologic jaw relations and occlusion of complete dentures. J Prosthet Dent 2004;91(3):203-05.

Centric-relation recording techniquesSwallowing or free closure (Shanahan)Chin point guidanceChin-point guidance with anterior jigBilateral manipulation

Kantor ME, Silverman SI and Garfinkel L. Centric-relation recording techniques-a comparative investigation. J Prosthet Dent 1972;28(6):593-600.

Chin point guidance

Chin-point guidance with anterior jig

Bilateral manipulation

Median variability

Swallowing or free-closure records - 0.40 mmChin-point guidance - 0.14 mm Chin-point guidance with an anterior jig - 0.07 mmBilateral manipulation - 0.05 mm

median variability 0.40--these records deviated 0.40 mm from their mean point.55

Pantography Used clinically to measure mandibular movementGraphic record in three planes

Types-Mechanical (by McCollum and Staurt)Electronic

Pantographic tracings

Eccentric relation recordsProtrusive relation

Lateral relation

Left lateral Right lateral

Protrusive jaw relationRegister the influence of the condylar paths over the movements of the mandible

Christensens phenomenon

Protrusive interocclusal record (Whip mix)

Protrusive interocclusal record (Hanau)

Lateral jaw relations

Influence the intercuspation of teeth in working mastication

Used to program the articulator

Lateral interocclusal records (Whip mix) Set side shift guide at 45o

Mark 6mm from centric relation along Left Lateral tracing and centre the hole of plastic piece over it

Right condylar ball is in protrusion

Side shift guide brought in contact with the ball

Lateral interocclusal records (Hanau)

L = H/8 + 12

( H Horizontal condylar inclination L Lateral condylar inclination)

Clinical protocolNair CK. Programming the semiadjustable articulator. Trends in Prosthodontics 2011;2(1):12-14.

Protrusive records made of plaster at 2mm, 4mm, 6mm, 8mm and 10mm

Nair CK et al. Relationship between protrusive record and horizontal condylar guidance angle. Trends in Prosthodontics 2011;2(1):15-16.

Programming the articulator using interocclusal records to note variation in the condylar guidance angleNair CK et al. Relationship between protrusive record and horizontal condylar guidance angle. Trends in Prosthodontics 2011;2(1):15-16.

Nair CK et al. Relationship between protrusive record and horizontal condylar guidance angle. Trends in Prosthodontics 2011;2(1):15-16. Right condyle( Mean SD)Left condyle ( Mean SD) 2mm 7.083o5.42o 10.42o 7.22o4mm 14.17o 6.56o17.08o 10.97o6mm 18.75o 5.28o 22.5o 8.66o8mm18.33o 3.89o 18.75o 5.69o10mm 11.25o 4.33o 14.58o 5.42o

References:Nair KC, A primer on complete denture fabrication, 1st edition, 2013, Ahuja publication, India Pp 67-77

Winkler S, Essentials of Complete Denture Prosthodontics, 2nd edition, India, A.I.B.T.S Publishers and distributors, 2009, pp 192-201.

Sharry JJ, Complete Denture Prosthodontics, 3rd edition, USA, Mcgraw-Hill Book Company, 1974, pp 215-222.

Manappallil JJ, Complete Denture Prosthodontics, 1st edition, India, Arya (Medi) Publishing House, 2006, pp 145-67, 181-83, 194-98.

Saizer P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent 1971;26(6):581-91.

Avant WE. Using the term centric. J Prosthet Dent 1971;25(1):12-15.

Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. J Prosthet Dent 2005;93:305-10.

Shanahan TEJ. Physiologic jaw relations and occlusion of complete dentures. J Prosthet Dent 2004;91(3):203-5.

Kantor ME, Silverman SI and Garfinkel L. Centric-relation recording techniques-a comparative investigation. J Prosthet Dent 1972;28(6):593-600

Kingery RH. A review of sone of the problems associated with centric relation. J Prosthet Dent 1952;2(3):307-19.

Bissasu M. Use of the tongue for recording centric relation for edentulous patients. J Prosthet Dent 1999;82:369-70.

Gothic arch tracing ppt.

Nair CK. Programming the semiadjustable articulator. Trends in Prosthodontics 2011;2(1):12-14.

Nair CK et al. Relationship between protrusive record and horizontal condylar guidance angle. Trends in Prosthodontics 2011;2(1):15-16.