failure in removable part denture my ppt

GOOD MORNING

FAILURES IN REMOVABLE

PARTIAL DENTURE

DR ZARIR

CONTENTS

1. Introduction 2. Failures in diagnosis and treatment planning 3. Failures in mouth preparation 4. Failures in framework design 5. Failures in laboratory procedures 6. Failure in support for denture bases 7. Failures in occlusion8. Failure in patient-dentist relationship9. Conclusion 10. Bibliography

INTRODUCTION

Failure of removable partial dentures is due to inadequate

1. Diagnosis and treatment planning2. Mouth preparation procedures3. Design of framework4. Laboratory procedures5. Support for denture bases6. Occlusion7. Patient-dentist relationship

Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part I. J Prosthet dent; 2001;86(3); 251-261

Making RPD’s using a 2 appointment system: one for diagnosis definitive impressions, mouth preparation procedures and second for insertion of partial denture.

FAILURE IN DIAGNOSIS AND TREATMENT PLANNING

A.ERROR:-

1. IMPROPER DIAGNOSIS


SOLUTION:-

1ST appointment:- make an assessment of the patient, diagnosis, take radiographs and make primary impression2nd appointment:- make mouth preparations and impressions for definitive casts and jaw relation can also re carried out.3rd appointment:- try in of the metal framework prosthesis.

4th appointment to deliver the denture and adjust the occlusion. Give the patient instructions essential to successful function and maintenance of the denture

5th mandatory follow up


Failure to a the analyze set ofdiagnostic casts for each patient.

B.ERROR:-

SOLUTION:-

1.After only an intraoral examination, a patient may appear to have a simple problem when, in fact, the situation is very complicated.

2. Always make diagnostic casts and evaluate them thoroughly before committing to treatment


C. ERROR:-

Failing to remove debris and plaque from the teeth before impression is made

Routinely clean the teeth with a lubricating prophylactic paste before making an impression,

In cases of extensive calculus deposition oral prophylaxis has to be carried out

SOLUTION:-


2) SurveyingFailure to use a surveyor during treatment planning

SOLUTIONIt is the responsibility of the dentist to survey and draw the design on the diagnostic cast before sending it to the lab


FAILURES IN MOUTH PREPARATION PROCEDURES

1) Improper guide plane preparations:

Stewart’s Clinical Removable Partial Prosthodontics. 4th edition

2) Improper height of contour:

Improper positioning of the retentive clasp arm and reciprocal clasp arm

Retention and Stability of the prosthesis affected.

3) Rest and Rest Seat Preparation:

Movement of the abutment tooth or sliding of the prosthesis

The forces transmitted from the prosthesis to abutment teeth would occur against the inclined plane.


Occlusal rest Preparation in a multi- surface Amalgam Restoration.

-Amalgam tends to flow when placed under constant pressure or even excess preparation.

ERROR:-

SOLUTION:-

Dentist failing to tripod the designed diagnostic cast

When the dentist designs the cast it has to be tripoded so that the lab technician can easily duplicate the design.


FAILURES IN DESIGN OF FRAMEWORK

1.Tripoding

2. Design transfer to master cast:

1. The design has to be outlined on the refractory cast with minimum pressure.

2. The cast must not be abraded during the transfer of the design

3. The position of individual clasp tips is most important in the

design transfer


3) Incorrectly located RPD components:

Incorrectly located major connector


1. Flexible major connector

2. Impinging on the gingival margins

3. Failure to provide relief where is crosses the gingival margins

Incorrect use of clasp designs

Use of clasps that are too broad in tooth coverage and have too little consideration for esthetics

4) Beading of the cast:

Tissue blanching and inflammation or ulceration seen when the beading on the cast done too deep


5) Block out: Improper

seating of the framework:-

-Block out if not done properly permitting rigid part of the framework to be placed in undercuts.


Framework that does not contact the tooth:-

Block out wax addedabove the height of contour line or on the guiding planes and not removed during

shaping of wax.


6) Contouring of the block out wax:

1. Done with blockout instrument properly positioned, excess wax is carefully removed.

2. The blockout instruments can be electrically heated or warmed over a flame


7) Relief: .


ERROR:- Metal framework impinges on the soft tissue

SOLUTION:- 1. The thickness of the relief wax has to be

adequate

2. The wax must not be separated and lifted up from the cast during duplication.

FAILURES IN LABORATORY PROCEDURES

1) Poor cast-forming procedures:

Cast is inaccurate: not a true

reproduction of the anatomy of the

mouth.

2) Duplication:

1. Block out and relief wax melted by reversible hydrocolloid.

2. Mold damaged during

removal of the master

cast.


3) Refractory cast:

ERROR: Abraded refractory castSOLUTION:-1.Surface treatmentof the cast has to be carried out.

2. The cast must not be retrieved until it is completely set.

3. The refractory cast is then trimmed on a dry cast trimmer.


4) Waxing:

ERRORS:- patterns separate from the refractory cast.

SOLUTION:- 1. The plastic patterns have to be

glued properly to the design outline on the refractory cast

2. Mixture of acetone and plastic pattern scraps mixed to watery consistency ( TACKY LIQUID)

3. The liquid has to be applied in a very thin layer


5) Failure of technician to follow the design and written instructions:


6) Spruing

ERROR:- 1. Attaching the sprue lead to a thin section of waxed framework

SOLUTION:- Always sprue to the bulkiest portion of the pattern

Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part II. J Prosthet dent; 2001;86(3); 251-261

Small particles of investment in the casting:-

-Sprue leads joined to main sprue on wax pattern improperly.

-Sprue hole was enlarged by cutting with knife, leaving roughened surface for metal to flow over.


Metal spilled when casting:-

-Sprue hole is too small for Bulk of metal.

-Sprue leads broken during investing

procedure

Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part II J Prosthet dent; 2001;86(3); 251-261

Internal mold deformations:-

-Constriction in the sprue lead

Porosity in casting:-

-Improper spruing procedure

Pattern failed to casting:-

-Pattern separated from crucible former during investment


7) Investing:

If the cast is dried with teeth up,

white materials would be

deposited around the teeth. This is

due to deposition of salts which

form a positive layer that cannot

be removed without scraping and

damaging the cast.

Cracks in the cast

Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part III. J Prosthet dent; 2001;86(3); 251-261

8) CASTING defects:- Pitted casting

If the design is placed on the refractory cast with a graphite pencil….

Contaminates…..

Burn out temperature…..


Metal nodules and rough area on cast framework

-Failing to use surface tension reducer correctly on the waxed patterns would cause air trap, when paint on investment flows

-If the surface tension, reducer is not allowed to dry before applying the paint on investment


Incomplete casting and rough areas or fins in casting

-W: P ratio.

-If paint on investment layer is too thin.

-If the paint on layer is too thick.


Porous cast frame work

If the mold moves in the

casting machine as the

casting arm starts to spin,

molten metal sometimes

may miss the sprue hole

and spill outside the mold.


Incomplete casting

1. If the sprue hole faces

upward during burn out.

2. Casting temperature

of metal….


Warpage of the Frame work

1.The air pressure of the

nozzle of air abrasion

machine is about 100 psi…..

2.If sufficient time is not

allowed for the metal to cool

to room temperature in the

investment (quenching the

mold)…..

Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part III J Prosthet dent; 2001;86(3); 251-261

Nicks on the metal casting

1. Carelessly cutting off the

sprue leads

2. Using the wrong mandrel

in high spread lathe


Framework is too loose

Carelessly grinding the

inside of clasps


Fracture of the clasps

Removing too much metal

from retentive clasps.

An improperly tapered

clasp or one that is thin

or having nicks encourages

breakage by concentrating

the strain….

Electro polishing for a

longer time.


Warpage of the framework

Abrasive rubber wheels and

points can build up heat in the

framework very quickly

Loose frame work

Polishing removes a definitive

layer of metal.


Distorted frame work

1.Clasps and other parts of

the frame work can easily

catch in the polishing

wheel.

2.The force

usually distorts the

framework and injures the

operator.Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part III

J Prosthet dent; 2001;86(3); 251-261

Incomplete Casting of the Metal frame work

1. Metal too cold when cast.

2. Improper spruing.

3. Gas trapped in mold.


9) Mixing and packing acrylic resin:

1. Packing the acrylic material

into the flask before allowing them to cool down at room temperature

2. Packing the resin into the flask before it is ready to pack.

3. Underfiling the mould.Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part III

J Prosthet dent; 2001;86(3); 251-261

10) Deflasking and polishing the removable partial denture:

1. Distorted framework

2. Increase in the vertical dimension

3. Warpage of framework

4. Scratches on the final metal framework

5. Damaged denture teeth


Distorted clasps

-Using a cloth wheel that was not broken properly would result in damaged removable partial denture or injure the operator.

-A new cloth wheel has strings of material protruding from it.


-The strings could tangle in the clasp or other parts of removable partial denture and snaps the removable partial denture from the operator’s hands throwing it out with great force.


Scratches on the denture

-Course pumice leaves scratches.

-It would be difficult to adequately polish around the necks of denture teeth with a cloth wheel or a lathe mounted bristle brush without damaging the contours of the teeth.


Dull appearance of the denture

Detergent alone would not adequately remove polishing compound from the removable partial denture.

The remaining residue would prevent the removable partial denture from achieving the luster.


11) Fitting the framework to the cast and mouth:

1. Framework too retentive on the definitive cast.

2. Frame Work not fitting exactly in the mouth.


12) Finishing and polishing of framework:

Polished surface is dull with fine scratches

-Sequence of finishing steps not followed

Major and minor connector over thinned and

flexible.

-Framework over thinned with abrasive stones

during finishing


Clasps is nicked or notched

Framework distorted

-Frame work caught in lathe during finishing.


13) Fitting and adjusting the removable partial denture to mouth :

Failing to evaluate the denture borders when

placed intra-orally.

Loss of retention and support.

Soreness or Ulceration of soft tissue in the

patient’s mouth


Increase in the vertical dimension of occlusion


Warpage of the RPD -If the patient does not seat the removable partial denture correctly, they may warp the removable partial denture or be injured by it

Inadequate ridge quality and

contour

Complete extent of the

residual ridge not covered by the denture

Inadequate coverage of

basal seat tissues

Failure to record basal seat tissues in supporting form

FAILURE IN SUPPORT OF DENTURE BASE

1) Articulation:

Error in articulation of the cast

FAILURES IN OCCLUSION


2) Face bow transfer:

Alteration in the jaw relation

1. Positioning the face bow on patient’s face.

2. Placement of the fork


3. Rocking of the record

4. Trimming of the record or metal showing through the record.

5. Face bow transfer not done.

3) Correction of occlusal plane:

Sensitivity of teeth or incipient caries- after enameloplasty

4) Selecting and arranging teeth:

Unable to interdigitate artificial teeth with opposing natural dentition

Insufficient space to set posterior tooth replacement

Anterior replacement teeth too short for satisfactory esthetics

Dentists failing to select type, shade and mold of the denture teeth to be used resulting in unaesthetic prosthesis not accepted by patient

FAILURE IN PATIENT-DENTIST RELATIONSHIP

Failing to make a follow up appointment

for the patient

Failure of dentist to provide adequate dental health care information, including care and use of prosthesis

CONCLUSION

REFERENCES

1. Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part I & . J Prosthet dent; 2001;86(3); 251-261

2. Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part II & . J Prosthet dent; 2001;86(3); 262-276

3. Rudd & Rudd, A review of 243 errors possible during the fabrication of a removable partial denture: Part III & . J Prosthet dent; 2001;86(3); 277-286

REFERENCES

4. McCracken’s: Removable partial Prosthodontics. Eleventh edition 2005

5. Stewart’s Clinical Removable Partial Prosthodontics. fourth edition

6. A clinical overview of removable prostheses:3. principles of design for removable partial denture .Dent update 2002;29.

7. A clinical overview of removable prostheses:4 technological consideration when designing removable partial denture. Dent update 2003;30:7-9

THANK YOU

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