5. metal ceramic restoration

8/12/2019 5. Metal Ceramic Restoration

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TOOTH PREPARATION FOR METAL

CERAMIC CROWNS



METAL CERAMIC RESTORATION

- Combines the strength and accurate

fit of a cast restoration with the

cosmetic effect of a ceramic crown.

- With the metal understructure,

metal-ceramic restorations

have greater strength than

restorations made ofceramic alone.



Advantages

• Strength and stability provided by the underlying metal

• Esthetic having a nearly natural appearance

• Used in single units to bridges

•High rate of Long Term Success



Disadvantages

• While cosmetic appearance is excellent, they are not asaesthetically pleasing as other types of crowns.

• Gingival inflammation causing gray line (due to metal) compared toporcelain crowns and Porcelain-Fused-to-Gold Crowns.Requires more of the tooth structure to be removed because of its

thickness.• The porcelain crown can chip or break off.

• The porcelain surface of the crown can significantly wear thoseteeth that bite against it.

• In cases where this type of crown has broken, it is generally the

layer of porcelain that has fractured off. This usually reveals themetal tooth substructure underneath, which is often gray inappearance.



INDICATIONS

• The metal-ceramic crown is indicated on teeth that require

complete coverage, where significant esthetic demands are

placed on the dentist (e.g., the anterior teeth).

• It should be recognized, however, that, if esthetic

considerations are paramount, an all-ceramic crown has

distinct cosmetic advantages over the metal-ceramic

restoration; nevertheless, the metal-ceramic crown is more

durable than the all-ceramic crown and generally has superior

marginal fit.

• Furthermore, it can serve as a retainer for a fixed partial

denture because its metal substructure can accommodate

cast or soldered connectors.



• Metal-ceramic crown may be successfully modified to

incorporate occlusal and cingulum rests as well as milled

proximal and reciprocal guide planes in its metal substructure

. Whereas the all-ceramic restoration cannot accommodate a

rest for a removable prosthesis.

• Typical indications - extensive tooth destruction as a result of

caries, trauma, or existing previous restorations that

precludes the use of a more conservative restoration

• Within certain limits this restoration can also be used tocorrect the occlusal plane.



METAL-CERAMIC RESTORATION

Can be used in a wide

variety of situations

including the

replacement of missing

teeth with fpd’s.



CONTRAINDICATIONS

- Contraindications for the metal-ceramic crown, as for all fixed

restorations, include patients with active caries or untreated

periodontal disease.

- In young patients with large pulp chambers, the metal-

ceramic crown is also contraindicated because of the high risk

of pulp exposure. If at all possible, a more conservative

restorative option such as a composite resin or porcelainlaminate veneer is preferred.



- A metal-ceramic restoration should not be considered

whenever a more conservative retainer is feasible, unless

maximum retention is needed-as for a long-span FPD.

- If the facial wall is intact, the practitioner should decide

whether it is truly necessary to involve all axial surfaces of the

tooth in the proposed restoration. Although perhaps

technically more demanding and time consuming, a more

conservative solution usually can be found to satisfy the

patient's needs that may provide superior long-term service.



ARMAMENTARIUM

1. LAB KNIFE WITH NO:25 BLADE

2. SILICONE PUTTY

3. FLAT – END TAPEREDDIAMOND

4. ROUND – END TAPEREDDIAMOND

5. SMALL WHEEL DAIMOND

6. LONG NEEDLE DAIMOND

7. RADIAL FISSURE BUR(ROUNDED SHOULDER)

8. MODIFIED BINANGLE CHISEL



ANTERIOR METAL-CERAMIC CROWNS

Silicone index

made before

tooth

preparation

If the tooth badly is

broken down,

index made on waxed

up diagnostic cast.



ANTERIOR METAL-CERAMIC CROWN

PREPARATION

Step no : 1

Placement of depthorientation grooves -

( 1.2mm ) the labial

grooves cut in two sets

1. one set parallel with thegingival half of labialsurface

2. one set parallel with theincisal half of labialsurface




PREPARATION




To achieve adequatereduction withoutencroaching upon the pulp – facial surface prepared in

two planes that correspondroughly to the twogeometric planes presenton the facial surface of anuncut tooth




PREPARATION

STEP NO : 2

Incisal reduction- (2mm)

with flat –end

tapered daimond.




PREPARATION

Inadequate incisal reduction

results in poor incisal

translucency




PREPARATION

STEP NO : 3

Labial reduction

(incisal half)

with flat - end

tapered daimond.




PREPARATION

STEP NO :4

Labial reduction

(gingival half)

with flat-end

tapered daimond

to create shoulder finish

line.




PREPARATION

STEP NO : 5

Lingual reduction

(0.7 -1mm )

using small wheel

daimond.




PREPARATION

STEP NO :6

Initial proximal reductionUsing long needle

daimond




PREPARATION

STEP NO : 7

Lingual axial

reduction

round - end

tapered daimond

(chamfer finish line)




Adequate reduction is

essential for achieving a

good esthetic

result.




Inadequate space for a

sufficient thickness of

ceramic material-

1. Poorly contoured

restoration affecting

both esthetic and health

of the surrounding

gingiva.




A uniform

reduction of

approximately

1.2- 1.5mm is needed

over the entire

facial surface.




If the facial surface is prepared in a

single plane that is an extension of the

gingival plane

– pulp exposure- overcontoured “block”

- Improper shade




Facial surface prepared in one

plane that has adequate facial

reduction in the incisal aspect

facial surface overtapered

and too close to the pulp.




PREPARATION




PREPARATION

IMPROVED ESTHETICS

ALL CERAMIC LABIAL

MARGIN

THIS ELIMINATES THE

METAL COLLAR AT THE

FACIOGINGIVAL MARGIN

OF THE FINISHED METAL-

CERAMIC RESTORATION



POSTERIOR METAL-CERAMIC CROWNS




STEP NO : 1

OCCLUSAL REDUCTION

FOLLOWED BY

FUNCTIONAL CUSP

BEVEL




STEP NO : 2

DEPTH ORIENTATIONGROOVES




STEP NO :3

FACIAL REDUCTION-

OCCLUSAL HALF



POSTERIOR METAL-CERAMIC CROWN

STEP NO :4

FACIAL REDUCTION

GINGIVAL HALF




STEP NO: 5

PROXIMAL

AXIAL

REDUCTION




STEP NO :6

LINGUAL AXIAL

REDUCTION




STEP NO : 7

AXIAL FINISHING



References

• Contemporary fixed prosthodontics ; Rosensteil,

Lang,Fujimoto;3rd ed.

• Fundamental of fixed prosthodontics ; Shillingburg etal,3rded

5. metal ceramic restoration

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