Ceramics

Question 1

Porcelain

COMPOSITION

Answer 1

feldspar 60-80%, glass phase leucite
quartz 15-25%, stability
kaolin 0-5%, moldability
metaloxides Shade

Question 2

Glass-based porcelains (silica-based)

Answer 2

– Feldspathic porcelains

– Reinforced feldspathic porcelains

Question 3

•Metal oxide ceramics (High-strength)

Answer 3

Aluminum-oxide ceramic (alumina)

Zirconium-oxide ceramic (zirconia)

Question 4

What does Sintering do?

Answer 4

making objects from powder, by heating the material in a sintering furnace below its
melting point (solid state sintering) until its particles adhere to each other

Question 5

Feldspathic porcelain uses

Answer 5

• Veneers

* Veneering porcelain fused to metal (PFM) crowns

Question 6

Reinforced feldspathic porcelain can be reinforced with…

Answer 6

1. Alumina reinforced feldspathic porcelain
2. Leucite reinforced feldspathic porcelain
3. Lithium reinforced feldspathic porcelain
   Lithium disilicate crystals, flexural strength: 340 MPa
4. Fluorapatite reinforced feldspathic porcelain
   Fluorapatite crystals, flexural stregth: 110 MPa
   Al2O3 crystals, flexural strength: 131 MPa
   Leucite crystals, flexural strength: 220 MPa

Question 7

Aluminum-oxide ceramic (alumina), flexural strength:

Answer 7

200 MPa

Question 8

– Zirconium-oxide ceramic – ZrO 3 (zirconia), flexural strength:

Answer 8

1000-1500 MPa

(yttria) added

Question 9

Crystal forms of zirconia:

Answer 9

cubical (high temperature)

tetragonal (while cooling down) monoclinic (room temperature)

Question 10

Non-silica-based ceramics Considerations

high-strength ceramics

Answer 10

– Special silane application (chemical bond to metal-oxides in ceramic and to cement)
– Resin based cement

Question 11

Silica-based ceramics Considerations

glass-ceramics

Answer 11

– Etching with hydrofluoric acid (increases surface roughness for better micromechanical retention)
– Silane application (chemical bond to silica in ceramic and to cement)
– Resin based cement