Ceramics for PFM-Geraldi

Question 1

What are the indications for PFM restorations?

Answer 1

• Anterior & Posterior teeth requiring complete coverage
• Retainer for FDP (bridges)
• Endo treated tooth (Metal post)
• Esthetics

Question 2

What are the frequency of crowns and fixed prostheses in the United States?

Answer 2

• All ceramic restorations-80%
• PFM: 17%
• Full-cast: 2%
• Resin-based composite(RBC): 1%

Question 3

What are the top 3 choices for materials in anterior crowns?

Answer 3

1. lithium disilicate (54%)
2. Layered Zirconia (17%)
3. Leucite-reinforced glass ceramic (13%)

Question 4

What are the top 3 choices for materials in posterior crowns?

Answer 4

1. All zirconia (32%)
2. PFM (31)
3. Lithium dislocate (21%)

Question 5

What are the requirements for ceramics in metal-ceramic restorations?

Answer 5

• simulate appearance of natural teeth
• Fuse at low temperatures
  
  • Low fusion temperature
• Thermal expansion coefficient compatible le w/alloys used for metal framework
• age well in oral environment
• low abrasiveness

Question 6

What are the 2 phases of Glassy (Felspathic) ceramics?

Answer 6

• Crystal Phase=Leucite
• Glass phase=Silica

Question 7

What are the types of feldspathic ceramics?

Answer 7

Feldspar

quartz or silica

alumina

Question 8

Characterize feldspar ceramic

Answer 8

KAlSi3O8

• Feldspar rocks are gounded
  
  • use strong magnets to remove iron compounds
  • milled for purest powder
• not used for large FDPs
  
  • esthetic

Question 9

Characterize quartz or silica

Answer 9

SiO2

• matrix component (55-65%)
• Function=translucency of restoration

Question 10

Characterize alumina

Answer 10

Al2O3*SiO2*2H2O

• added to reinforce
• Kaolin
  
  • hydrated aluminum silicate
  • used in limited amount (4%)
  • opaque properties
  • used in composition of dental ceramics
    
    • binds loose ceramic particles together

Question 11

Characterize glass modified properties of porcelain

Answer 11

• can be altered to have lower fusion temperature
• alkali metal ions/rare-earth oxides
  
  • disrupt SiO4 network
    
    • break oxygen-silicon bond
    • K, Na, Ca, Mg, Pb

Question 12

Glassy Phase

Answer 12

• Aka Amorphous phase
• Silica
• 80-90% of volume
• Translucency
• Low toughness and strength

Question 13

Leucite

Answer 13

• Controls Thermal Expansion
  
  • match dental alloys

Question 14

Pigment Oxides

Answer 14

• first used w/feldspar
  
  • ground to fine powder
  • blended w/ceramic powder frit
    
    • provide hue and chroma

Question 15

Degassing Treatment