SAS 21 - USES OF DENTAL PORCELAIN

Degassing

Removes impurities from the alloy and forms oxide layer

Sintering

Firing of porcelain paste on metal by heating porcelain in an oven

1. Opaque
2. Gingival
3. Glaze
4. Characterization

Layering of Porcelain:

Opaque

This layer of porcelain hides metallic color

Gingival

This player of porcelain is placed one-half of the crown, this mimics dentin of the tooth

Glaze

Final porcelain layer, provides polished surface

Characterization

This porcelain layer add surface stains/cracks

• Good to excellent esthetics.

• Excellent fit of the metal framework.

• Reliable solder joints on bridges.

• More favorable cost-benefit ratio (durabililty)

• Well-known technology, easy to apply

• It has the strength of cast metal crowns with the esthetics of the all ceramic crowns.

ADVANTAGES OF PFM CROWNS:

• Potential metal allergy.

• Unesthetic metal margin due to metal margin exposure

• Potential for periodontal diseases. (to achieve better esthetics, the facial margin of an anterior restoration is often placed subgingivally which increases the risk for periodontal problems)

• Difficulty of accurate shade selection.

• Their preparation requires more tooth reduction to sufficient space for the restorative materials.

• Problems with translucency.

• Chipping of ceramic margins.

• Wear of the antagonist.

• High cost compared to plastic restorations.

DISADVANTAGES OF PFM CROWNS:

Dark line

Located at the facial margin that is associated with the metal collar or metal margin when gingival recession occur

Ceremic margin

The unesthetic dark line can ve minimized by designing the crown with a _______ or using a knife edge margin or metal that is veneered with opaque shoulder porcelain.

ceremic

Wear of the antagonist is due to the hardness of

inadequate occlusal adjustments

The most damage is because of buying premature occlusal contacts and

All Ceramic Restoration

This restoration does not use any metal substructure

Core Porcelain

All Ceramic Restorations do not use any metal substructure, instead they use what?

1. Aluminous or Magnesia based porcelains
2. Glass-infiltrated aluminous porcelain
3. Castable Porcelain
4. Press Porcelain

Core Porcelain:

ceramming

Castable Porcelain are crystallized after casting in oven in a process called

Glaze material

used to attain specific shade

• Biocompatibility

• Superior esthetic (no metal display)

• Good bonding (cohesion) between the ceramic coping and porcelain veneer.

• Resist the degradation in oral fluids.

• Increased translucency provides improved esthetics when the adjacent teeth or restorations are translucent.

• The tooth-shaded margin, which need not be placed under the gum line will not irritate the gums andprevents gum recession.

• Low thermal conductivity.

ADVANTAGES OF ALL CERAMIC CROWNS:

metal-free crown,

Many patients with PFM experience sensitivity that can be painful, especially with extreme temperature changes when eating or drinking something cold or hot. With ________,these pains are reduced drastically, or are non-existent.

zirconia ceramics

Better strength than other restorations because in these crowns, porcelain is engineered with high strength compounds like

Veeners

A layer of material placed over a tooth, either to improve aesthetics of a tooth or to protect the tooth's surface from damage.

1. Composite
2. Dental Porcelain

The two main types of material used to fabricate Veneers:

Inlay

Is usually an indirect restoration (filling) consisting of a solid substance (gold, porcelain) fitted to a cavity in a tooth and cemented into place.

Onlay

The same as an inlay, except that it incorporates a REPLACEMENT FOR A TOOTH CUSP by covering the area where the missing cusp would be.

Crowns

Cover all surfaces of the anatomical tooth crown