pros 5 - jaw relation

8/12/2019 PROS 5 - Jaw Relation

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Occlusal Rims and JawRelation

Dr Adam Husein


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Outline

Introduction

Objectives

Terminologies

Materials Procedures

Recording jaw relation


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Introduction

Laboratory stage following secondary

impression is the construction of basesand rims

Secondary impressions master/working

casts bases occlusal rims Bases and rims are then used for

recording jaw relation (JR) or biteregistration or maxillo-mandibularrecording (MMR)


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Introduction

Construction of occlusal rims or bite block

is a laboratory stage Jaw relation record (JR) is the clinical

stage


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Base

Same or different materials

Rim


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Different materials


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Materials for Bases

Acrylic resin

Cold cure Light cure

Thermoplastic material Wax

Do not use not stable


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Bases

Well adapted and conform closely to the

master cast Stable on the cast in situ

Free of voids and surface projections onthe impression surface

No more than 1 mm thick over the residual

ridge to prevent the base interfering withthe placement of the denture teeth


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Bases

2 mm thick in the post dam area of the

maxillary denture (and 2 mm thick in thelingual flange of the mandibular denture)

to impart rigidity

Easily removed from the cast

Smooth and rounded so as to reproduce

the contours of the master cast

Constructed in materials that are stable


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Common materials used as bases


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Summary of stages

Stages

Clinical Laboratory

History and exam

Primary

Secondary

JR

Try in

Issue

review

Study model or primary model

Master cast

Working cast

Bite blocks

Teeth arrangement

Processing

Wax up

Flasking

Trimming and polishing


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Objectives

Creating and outlining the form of the

upper denture Recording of intermaxillary relations

Selection of teeth


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Occlusal registration stage

Three components

Creating and outlining the form of the upperdenture

Recording of inter-maxillary relations

Selection of teeth


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Clinical Procedures

Correct patient

Inspect the prosthesis properly done ornot polishing and finishing

Following prescription Ensure that the rim is well adapted to the

master cast

Disinfection appropriately

Try in patients mouth


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Summary of steps in JR

1. Lip support

2. Incisal plane3. Occlusal plane

4. VDR, VDO and freeway space5. Lower rim

6. Recording JR

7. Midline, smile line and canine line

8. Shade and mould


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1.Lip Support

Restoration of the vermilion border

Restoration of the philtrum

90 vertical naso-labial angle


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Naso-labial Angle

The angle between the columella of the

nose and anterior surface of upper lip inthe sagittal plane (Patnaik et al, 2003)

A preliminary study of determining naso-labial angle for Malay subjects

(Ramasamy and Husein, 2005)

12 males and 12 females

Mean angle for male 73 degrees

Mean angle for female 72 degrees


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Vermilion borderPhiltrum


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2. Incisal Plane

Determine the upper anterior plane

Upper anterior six is usually parallel to the inter-pupillary line

Foxs occlusal plane guide or any device e.g. awooden spatula


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Incisal Show

Determine the position of the incisal point

relative to the resting lip Usually 2 mm below, but should suit individual

case

Younger patients 4-5 mm

Elderly level with the resting lip or 1 mm above

In general, incisal point should correspond tothe vermilion border of the lower lip


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1. Lip support



6. Recording JR


8. Shade and mould


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3. Occlusal Plane

Using the canine points on the upper rim asreference points, the right and left posterior

planes are formed Accepted guideline this plane is parallel to the line

drawn from the inferior border of the alar cartilage to aposition two-thirds of the way up the tragus


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1. Lip support



6. Recording JR


8. Shade and mould

4 VDR VDO and Freeway


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4. VDR, VDO and Freeway

Space VDR/RVD vertical dimension at rest/rest

vertical dimension VDO/OVD vertical dimension of

occlusion/occlusal vertical dimension

Freeway space (FWS) or inter-occlusal

distance (IOD)


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FWS or IOD

Determined by a balance between the

elevator and depressor muscles attachedto the mandible, and the elastic nature of

the surrounding soft tissue in a natural

dentition

Resting vertical dimension vertical

dimension of occlusion (OVD) = FWS


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How to measure RVD

Facial measurements

Swallowing methods Biting force measurements

Phonetic methods Tactile methods

Electromyographic measurements Combinations are recommended


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Excessive OVD

Increased risk of trauma to the underlying

tissuesLack of FWS continuous clenching

Painful mucosa

Muscle soreness (especially masseter)

Clicking

Phonetic problems

TMD may develop


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Reduced OVD

Lack of support of the angles of the mouth

DribblingAngular cheilitis

Reduced masticatory efficiency Poor esthetics

Chin protrusion on closure


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5. Lower Rim

Trim to fit upper rim

Even contact with upper rim Contact at established OVD

Tongue position can be used as a guide


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1. Lip support


4. VDR, VDO and freeway space

5. Lower rim

6. Recording JR


8. Shade and mould


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6. Recording MMR/JR

Retruded contact position (RCP) or centricrelation

Reproducible Present with or without the presence of natural teeth

Curl the tongue back to touch the back of the palate

Methods Wax

Bite registration paste

Tracing

Staples

Methods chosen must be repeatable


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M t i l


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Materials

ZnOE or bite registration paste

S f t i JR


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1. Lip support


4. VDR, VDO and freeway space

5. Lower rim

6. Recording JR


8. Shade and mould

7. Midline, Smile and Canine


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7. Midline, Smile and Canine

lines Determine the positions of the mid points of the

upper canine Extend dental floss from the inner canthus of the eye,

via the lateral border of the alar cartilage (with thepatient smiling) onto the incisal edge of the upper rim

For completion, the following should be clearlymarked on the upper rim Centre line

High smile line

Canine points


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8 T th S l ti


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8. Teeth Selection

Dentists responsibility should not assign thetask to the technician

Categories Shape or mould

Shade

Guide Pre-extraction record

Photographs

Natural teeth or dentures admired by them

Casts

Patients wishes (spacing or crowding)

Teeth selection


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Teeth selection

Guide

Measurement from canine to canineInverted shape of the face

Shape of the edentulous maxillary arch

Both have no scientific credence

Posterior teeth

Teeth with cusps

Teeth without cusps

Hybrid teeth


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Color and Shade


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Color and Shade

Careful and deliberate consultation withpatients

Considerations

Age (teeth tend to become darker with age

although this is not always absolute)Patient preference

Skin color (usually darker skin whiter teeth)

Canine teeth slightly darker than incisors

Summary of Teeth Selection


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Summary of Teeth Selection

Dentists responsibility

Photographs or favored dentures ifpossible

Select lower to complement the upper Fulfill esthetic and functional requirements

Good practice to produce study models

prior to extracting all teeth for FF

Infection Control


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Infection Control

Disinfect properly before sending the work

to the lab

Conclusion


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Conclusion

JR is probably the most critical stage in

denture construction Carefully follow all the steps

Ensure to recheck the recording prior todischarging the patient


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hank Youhank You

pros 5 - jaw relation

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