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7/31/2019 Establishing Jaw Relation

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Establishing jaw relation andocclusal relationships for

removable partial denture

BYDR SALAH HEGAZY


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::


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The desired occlusal scheme of the

removable partial denture may vary fromthat of a complete denture( bilateralbalanced occlusion) to that of a fixedbridge.

The decision is made upon: A) The number and distribution of

remaining teeth.

B ) The existing periodontal conditions C) The type of occlusion in the opposing

arch.


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Establishing the jaw relation is necessaryif the opposing casts cannot be accuratelyhand articulated or if the denture is being

constructed at the centric jaw relationposition. It must be needed following thecorrected cast impression procedurebecause the lack of posterior occlusion in

class I & II partial edentulous arches.

When occlusal relationships areestablished to position the artificial teethcorrectly, the vertical and horizontalcomponents of the jaw relation are equallyimportant.


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Components: V.R.& H.R .

Methods ofEstablishing occlusal relationship:

1.Function generating path tech.

2.Articulator or static Tech.;

a. Direct opposition of casts( handarticulation)

b. Occlusal relations using occlusal rims

c. Jaw relation record by using frame workd. Complete upper and class I lower RPD


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Adequate toothnumber vs.

Inadequate tooth

number InterocclusalRecord to support

the bite registrationmaterials


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[C] Establishing vertical dimension of

occlusion:

Indications:

1- complete denture opposed RPD.

2- lost all posterior teeth in one or both

arches.

Procedure:

by measuring V.D of rest and then

subtracting 3 mm (amount of free-way

space).


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I -Vertical jaw relation:

[A] Vertical dimension:

Two vertical dimensions are recognized for each patient:

-Vertical dimension of rest is taken when the patient is inan upright position and is completely at rest.

-Vertical dimension of occlusion V.D is measured whenthe teeth contact in maximum intercuspal relationship.

- Free-way space the space between the teeth when themandible is in its resting stated, it's about 2-4 mm.


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[B] Altering the existing vertical dimension ofocclusion:

- The prosthesis should be constructed at

vertical dimension of occlusion, if the

natural teeth in opposing arch contact incentric occlusion.

-Changing the V.D of occlusion should be

considered only if the vertical dimension of

occlusion has been diminished.


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Signs and symptoms of diminished V.Dof occlusion:

Symptoms such as:1- Severe tooth wear

2- Tired aching muscle.

3-Unexplained pain in the head and neck.

4-Appearance of premature aging caused by

a shortened nose-chin distance.

Objective sign indicates loss of V.D in

excessive free-way space (i.e. more

than 4 mm).


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Signs:

1- If the occlusal surfaces of the teeth have beenworn excessively, it will not indicate that the V.D ofocclusion is lessened because a compensatingeruption of the teeth usually maintains the properV.D.

2- Also extreme anterior vertical overlap in which themandibular teeth strike the soft tissue of thepalate.

In these cases, no treatment needed to correct the

V.D of occlusion without more definite proof thatthe loss of V.D has occurred.

Cephalometric examination confirming migrationof condyles and greater than 4 mm free-way

space indicate loss of V.D.


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Prosthetic management for increase theexisting V.D:

-Increase in interocclusal height must beaccomplished with a temporary removableappliance (occlusal overlay). It's normally moreconvenient to construct the appliance to cover themaxillary teeth (to avoid interference with thetongue movement if cover mandibular teeth).

-All remaining teeth in both arches must becontacted by the prosthesis otherwise:

1- Teeth which do not contact by appliance tend to

erupt.2- If sufficient number of remaining teeth do not

contact, the appliance, the supporting teeth will besubmerged to an infraocclusal position .


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-Encroaching (obliteration) the free-way

space by prosthesis the person may

refuse to wear the appliance.

Or if he wears the appliance either

depressing the supporting teeth to

reestablish the free-way space.

or destruction of supporting alveolar

bone with loss of teeth.


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-Temporary appliance is used several months(usually 3 months) followed by permanent RPD.

-When permanent treatment is begun, it must be

planned so that all occlusal-dimension restoringprosthesis, fixed and removable are inserted atthe same time. Crown and fixed partial dentureshould never be inserted before the construction

of RPD to avoid destruction of the supportingtissue of teeth that maintain the V.D by crown orfixed restoration.


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II - Horizontal jaw relation:

Two horizontal relationships of the mandible tomaxilla are important in the occlusion of partialdenture.

Centric relation bone to bone relation.

It's repeatable, reliable position. Centric occlusion tooth-to-tooth relation.

It's learned habitual closure.

In more than 90% of all persons, centric relation

and centric occlusion do not coincide. Centricocclusion was always be anterior 1 to 2 mm tocentric relation.


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Factors influencing development of occlusion:

Several factors influence the occlusalscheme for RPD purposed by Hanau known

as Hanau quint:

Condylar guidance X incisal guidance=

Compensatory curves X Inclination of

occlusal plane X Cusp Height


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In complete denture, compensating curve,plane of orientation, incisal guidance and

height of cusp may be changed. The only

factor that cannot be altered is thecondylar guidance; therefore development

of occlusal scheme for C.D is easily

developed (i.e. anatomic or non-anatomic

teeth may be used).


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In partial denture, prominence ofcompensating curve, plane of orientation

and incisal guidance and height of cusp

are determined by the presence of naturalteeth; therefore the form of artificial teeth

is detected by the natural one.


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Methods of establishing occlusion:

There are basically two methods of

establishing the occlusion of RPD:

Functionally generated path technique.

The articulator or static technique.


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A ] Functionally generated path technique:

.All functional movements of the mandible are recordedon hard wax occlusion rim. The record represents thepathways of each tooth opposed to edentulous space.

The artificial tooth is positioned and formed to make

harmonious contact with its antagonist at all times

1. Acrylic record base is attached to framework then

construct hard inlay wax (purple) occlusion rim.

2. If occlusal contact between opposing natural teeth fail

to maintain the vertical dimension of occlusion

record this V.D (V.D of rest 3 mm).


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3. Occlusion rim is constructed so it's slightly

higher (keep the remaining teeth apart about

0.5 mm) and wider than the width of opposingtooth to record full range of functional

motion.

4. Patient continuously wear the framework and

occlusion rim for 24 hours except during

eating and drinking.

5. The framework with function generating path

occlusion rim (wax pattern) reset in mastercast.

6. The wax pattern is poured in hard stone to

produce stone record.


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7. The stone record and master cast with

function generating path occlusion rim ismounted on the articulator, the incisal guidepin is opened 1 mm before the artificial teethare positioned. The increase in V.D will return

to normal by selecting grinding the artificialteeth. Using water-soluble Prussian blue dyepaint the surface of stone record.

8. Selective grinding is made on articulator in

open and close movement only (i.e. articulatoris locked in centric relation). The articulator isnot moved into protrusive and lateral becausethese positions are incorporated in thepathway.


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Limitations to use the generatingpath:

The occlusion in one of the arches must be completed

before the generated path can be developed (one PD

constructed before the other can be made).

PD against complete denture Here complete the

partial denture by articulator method and functional

generating path for CD.


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Disadvantages:

Movement of distal extension base carrying the occlusion

rim is possible produce inaccurate pattern of path.

The pattern (path) developed in the wax is accurate forwax only but not for food stuffs (as masticatory cycledepend on the type and texture of food).

Advantages:

Elimination of the use of tracing device.

Elimination of the use of face-bow transfer

B ] A i l h i


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B ] Articulator technique:

a.Direct apposition of casts [Hand articulation]:

When hand articulation is used, tooth positioncan be determined by occluding the modeltogether (i.e. when sufficient opposing teethremain in contact to make the existing jawrelationship.

It should be used when only a few teeth are to bereplaced.

The occluded casts are secured together with

wooden sticks and sticky wax and mountedarbitrarily on an articulator.

No face bow is used.


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b. Occlusal relation using Occlusion rim:

The mandibular distal extensionocclusion rim may be constructed so that

the height will be even with cusps of theadjacent abutment tooth anteriorly andposteriorly to the height of theretromolar pad.


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Clinical procedure:

[A] When the vertical dimension is maintained byocclusal contact of several standing teeth in bothjaws and the tooth position cannot be determinedby occluding the models together centric

occlusion has been selected as the proper jawrelation.

1. The height of the occlusion rims must be

adjusted so that no contact takes placebetween opposing occlusion rims or betweenrim and opposing teeth. A space ofapproximately 1 mm is desired.


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2- If opposing occlusion rim is to be used one ofthese, usually mandibular rim is adjusted to

establish an ideal occlusal plane [because

the landmarks that are normally present.

The posterior height at of retromolar padand anterior height to the height of

remaining teeth] and the opposing maxillary

rim adjusted to short of contact.


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3. If opposing occlusion are to be used. The

recording medium is placed on the mandibular

rim. The maxillary rim should be indexed withseveral v-shaped notches.

4. The surface of occlusion rim that support the

recording medium should be roughened to

ensure that the record will remain attached toit.

5. If any portion of the wax occlusion rim shows

through the recording medium indicates thatincorrect jaw relation as any force occur in the

occlusion rim, the distal extension base will

depress the soft tissue beneath the base

relief the portion of the occlusion rim and the


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Project 1:

Record Bases & Wax Rim

Clinical Implications:

To evaluate and record the proper VDOand CR position when the remaining

dentition is not adequate enough to

support the bite registration material


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Model #1

Model #3*


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Use your eyes to estimate the correct

path of insertion. Then use small amount

of wax to block out the undercut.

Mi i


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Why?

To obtain a stable and

retentive recordbase and

yet avoid the damage

on the cast

Minimum

Wax Block Out

Where?Teeth: marginal gingiva,proximal surfaces, and

embrasures

Soft tissue: gross undercut


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Apply the separatingmedium

Wait for the first coat air dry, then apply

the second coat.


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Round, smooth,

and polish the

record base

Before adding the

wax rim, roughen

the acrylic surface

for mechanical

retention

Record base extension: 2 3 mm short of vestibule


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Record base extension: 2-3 mm short of vestibule



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R

e

Record base extension next to

the teeth:

Avoid the extend toward to

the tooth


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Record base:

2-3 mm thick

Do not overextend


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Extend the record base onto

the proximal, palatal/lingual

surfaces of the teeth to enhance

the retention, stability, and

support of the record base


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Keep the space for the

bite registration material


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Bite registration materials:

ZOE bite registration paste

Wax

Compound

Silicone


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Selectively adding

the wire clasps can

improve the

retention & stability

of the record basefor accurate jaw

record

d b


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Record base & wax

rim

Stable Good support

Rigid

Comfort

Accurate

interocclusalrecord


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c Ja relation record made b sing the


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c. Jaw relation record made by using theframework:

It's used if tooth position cannot be determinedby hand articulation.

If jaw relation appointment follow the

construction of an altered cast.1. It's advisable before removing the framework toexamine the relationship of the framework toteeth on the cast. Be sure that the occlusal rests

and other components of the framework did notmove during pouring the cast. If any change inposition of the framework was evident repeatthe alter impression.


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2. Acrylic tray should be removed from theframework by heating the tray material over a

burner until it starts to smoke and then pulling itby pliers.

Making the record base:

1. If the edentulous space is not too long hard

base plate wax may be used as a record base [itshould be formed over the acrylic resin retentionmetal in contact with edentulous ridge]

Autopolymerized acrylic resin should be used toconstruct the record base if the edentulous ridgeis long or if the interarch space is restricted.


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2. Soft tissue undercuts on the edentulous ridgemust be blocked with baseplate wax to avoid

damaging of the master cast when the acrylicrecord base is used.

2. Tissue stop under acrylic resin retention minor

connector will not contact cast following makingof altered cast to prevent framework frombeing moved during record base construction orprevent the framework from being disturbed

during packing of denture base, bead of autopolymerizing resin is placed between tissue stopand stone ridge and allowed to set before therecord base is adapted.


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Complete upper and class I lower RPD:

The vertical dimension of occlusion is determined by restV.D 3mm.

Establishing the centric relation.

Centric recording medium for seating the occlusion rims

together.

The upper cast mount of the articulator using face-bow and

the lower are using centric interocclusal record.


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Protrusive interocclusal record is used to adjust

horizontal condylar guidance.

Lateral condylar guidance is adjusted by the

following Hanau equation:

L= H/8 +12

The teeth are set in balancing occlusion.


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