OCCUSAL RELATIONSHIPS IN REMOVABLE PARTIAL DENTURE

INDEX1 Desirable occlusal contact relationship for removable partial denture

2 Method for establishing occlusal relationship

a) Direct apposition of cast.

b) Interocclusal records with posterior teeth remaining on record base.

c) Jaw relations records made entirely on occlusion rims.

d) Occlusal relations using occlusion rims on record base.

e) Establishing occlusion by the recording of occlusal path way.

3 Materials for artificial posterior teeth

4 Arranging teeth to an occluding template

5 Establishing jaw relations for a mandibular removable partial denture opposing a maxillary complete denture.

INTRODUCTION

The Fourth phase -functional and harmonious occlusion.

• Occlusal harmony-health of tissues.

• Attachment of the removable partial denture to the abutment teeth.

• Sustained stress -damaging -transient stress -complete dentures.

INTRODUCTION

Failure to provide and maintain adequate occlusion on the removable partial denture is primarily result of :-

- Lack of support for the denture base

- The fallacy of establishing occlusion to a single static jaw relation record.

- An unacceptable occlusal plane.

INTRODUCTIONThe establishment of satisfactory occlusion for RPD should include-

Occlusion

Occlusal disharmony

Centric relation

Eccentric jaw relations

Occlusal discrepancies

DESIRABLE OCCLUSAL CONTACT RELATIONSHIP FOR REMOVABLE PARTIAL DENTURES

• Following occlusal arrangements -harmonious occlusal relationship of removable partial dentures -stability - RPD

1. Bilateral contacts -opposing posterior teeth -centric occlusion

2. Occlusion for tooth supported RPD-natural dentition

- Direct retainers.

3.Bilateral balanced occlusion in eccentric position.

4. Working side -- mandibular distal extension denture.

5. Simultaneously working and balancing contact- max bilateral distal extension.

6. Only working contacts - maxillary or mandibular unilateral distal extension RPDS.

7. Kennedy Class IV RPDconfiguration

8. Balanced contact of opposing posterior teeth in a straight forward protusive relationship and functional excursive position -complete denture or bilateral distal extension maxillary RPD is placed.

9. Artificial posterior teeth -distally -or over the retromolar pad-shunting anteriorly.

METHODS FOR ESTABLISHING OCCLUSSAL RELATIONSHIP

Five methods…

1. Direct apposition of cast.

2. Interocclusal records with posterior teeth remaining on record base.

3. Jaw relations records made entirely on occlusion rims.

4. Occlusal relations using occlusion rims on record base.

5. Establishing occlusion by the recording of occlusal pathway.

A) Direct apposition of cast

• Sufficient opposing teeth -few teeth- occlusal abnormalities

METHOD-

• Apposing cast may be occlude by hand.

• Rigid supports - articulator.

• Occlusal analysis and the correction of any existing occlusal disharmony should precede the acceptance of such jaw relation record.

• Jaw relation record – inaccurate inter occlusal records-faulty jaw relation.

(B) INTEROCCLUSAL RECORDS WITH POSTERIOR TEETH

REMAINING

INDICATION:- Sufficient natural teeth - RPD - occluding of cast by hand.

• Interocclusal wax record-least accurate.

• A uniformily softened, metal reinforced wafer of base plate or setup wax -centric relation.

Correct closure - rehearsed -deviate into closing.

Wax -chilled -room temperature water.

Replaced a second time to correct the distortion that result from chilling and then again chilled after removal.

All excess wax removed. A wax record -further corrected -occlusal registration material

METHOD:-

• The opposing teeth -petroleum jelly - silicon preparation .

• The occlusal registration material -mixed -metal reinforced wax record.

• Placed -patient -closing in the rehearsed path .

• Occlusal registration material -set - corrected wax record removed - accuracy.

• Any excess wax matrix should be removed with sharp knife.

• Record should seat on accurate cast without discrepancy.

ADVANTAGE OF USING METALLIC OXIDE PASTE:-

1. Uniformity of consistency

2. Ease of displacement on closure

3. Accuracy of occlusal surface reproduction

4. Dimensionally stability

5. Less likelihood of distortion during mounting procedure

(C) OCCLUSAL RELATION USING OCCLUSION RIMS ON RECORD BASES

INDICATION:-

1. When one or more distal extension areas are present

2. When a tooth supported edentulous space is large

3. When opposing teeth do not meet

• In this instance occlusal rims on accurate jaw relation record base must be used .

METHOD:-

• Same as in the second method -occlusion rims - missing teeth .

• It is essential that accurate bases be used to help support the occlusal relationship.

• VLC , autopolymerising resin.

• Jaw relation record bases-same cast or duplicate cast.

METHOD FOR RECORDING CENTRIC RELATION ON RECORD BASE

• Modelling plastic occlusal rims - acceptable occlusal record.

• This method -time proved - equally in accuracy to any other method.

• Occlusal rims used -reduced in height -occlusal contact –VD.

• A single stop -terminal position .

• Quick setting impression plaster, bite registration paste, autopolymerising resin may be used.

(D) JAW RELATION RECORD MADE ENTIRELY ON OCCLUSION RIMS

INDICATION:-

1. When an opposing maxillary complete denture is to be made concurrently with a mandibular removable partial denture.

2. Used in those rare situation in which the few remaining teeth do not occlude and will not influence eccentric jaw movements.

3. Anterior teeth present.

Jaw relation records - occlusal rims.

• The occlusion rims -supported - accurate jaw relation record base.

• Method for recording jaw relation –CD.

• Direct inter occlusal method -stylus tracing.

(5) Establishing Occlusion by the recording of occlusal pathway:

•5 th method-occlusal pathway -occluding template.

•Static jaw relation record used with or without eccentric articulatory movements teeth arranged to occlude -occlusion.

•Movement made more complicated -natural teeth.

• Schyler-first ant tooth and incisal guidance-oral rehabilitation

• According to Thompson “Observing the occlusion with the teeth in static relation and then moving the mandible into various eccentric positions is not sufficient. A dynamic concept is necessary to produce an occlusion that is functional harmony with facial skeleton , the musculature , and the temporomandibular joint”

STEP BY STEP PROCEDURE FOR REGISTRING OCCLUSAL PATHWAY

After the framework has been adjust to fit the mouth, the technique for registration of occlusal pathways is as follow.

1. Support the wax occlusion rim -denture base

2. Occlusal rim -24hours or longer.

3. 3 D occlusion-tooth

4. After 24 hours -Gloss.

Any are of deficient are add this time.

5. After a second 24- 48hours period of wear the registration should be complete and be acceptable.

The remaining teeth that serve as vertical stops should be in contact and the occlusal rim should show an intact glossary surface, representing all each cusp in all extremes of movements.

•The registration of occlusal pathways has additional advantages.

• It makes obtain jaw relation possible under actual working length condition, with the denture framework in its terminal position, the opposing teeth in function, and the opposing denture, if present fully seated- lost VD.

MATERIAL FOR ARTIFICIAL POSTERIOR TEETH:

•Mostly acrylic resin teeth -porcelain teeth.

•Acrylic teeth with gold occlusal surface -natural teeth restored with gold occlusal surface.

• Porcelain teeth are generally used in opposition to other porcelain teeth.

• Acrylic resin tooth surface -abrasive paricles-wearing opposing gold surface.

• Reduced buccolingual width -posterior teeth.

• A acrylic resin teeth -modified -cast gold surface on their occlusal portions.

Arranging teeth to an occluding template

Occlusal surface modified Center of functional range Buccolingually Mesiobuccal cusp- buccal groove

ESTABLISHING JAW RELATION FOR A MANDIBULAR REMOVABLE PARIAL DENTURE OPPOSING A MAXILLARY COMPLETE DENTURE:

Condition: (1) If mandibular removable partial denture occludes with maxillary complete denture-

- If existing denture is satisfactory and occusal plane is oriented to an acceptable anatomic, function and esthetics position then complete denture need not to be replaced and treated as a intact arch.

- A face bow transfer is made of that arch and cast is articulated on the articulator.

- then face bow and complete denture is removed and irreversible hydrocolloid impression of the denture is made.

- A cast is formed from the impression and mount on the articulator.

- Than centric relation recorded and transferred to the articulator.

(2) When the removable partial denture replaces all posterior teeth and the anterior teeth are no interfering.

A central bearing point tracer is used may be mounted in the plate on maxillary denture.

A centric relation are recorded by means of introral stylus tracing against the stable mandibular base.

When a existing complete denture opposing a arch on which removable partial denture is fabricated. A cast of complete denture is used during the fabrication procedure.

(3) If the mandibular removable partial dentures is tooth supported then mandibular arch restored first.

The mandibular arch restored first -jaw relation established - full complement of opposing teeth. Thus maxillary complete denture - occluded with an intact arch.

Mandibular RPD – distal extension-occlusion on both simultaneously.

CONCLUSION

The balanced occlusion is the most important factor for the retention of the prosthesis.

The occlusion must be evaluate before the prosthesis fabrication start.

Preprosthetic mouth preparation must be done for better occlusion reproduction.

Proper method to be used for the record of correct occlusion.

Imbalanced occlusion is the main cause of retention loss of the prosthesis.

REFERENCES

Carr A B, Mc Givney G P, Brown D T, McCraken’s Removable partial Prothodontics. 11th ed, st louis: Mosby; 2008.

Stewart K L, Rudd K D, Kuebker W A, Stewart’s Clinical Removable Partial Prosthodontics. 2nd, Chennai; 2004.

Miller E L, Grasso J E, Removable Partial Prosthodontics. 2nd ed, Baltimore: Williams & Wilkins; 1979.