03 Materials Flashcards
What are the three main categories of ceramics?
- Silica based
- Polycrystalline
- Resin-ceramic hybrid
What are the three ways to make ceramics?
- Press
- Stack
- Milled
What three material properties matter the most?
- Fracture toughness
- Flexural strength
- Modulus of elasticity
Thicker ceramics lead to stronger ceramics when:
- There is no lab fabrication error
2. The ceramic is loaded above the center of rotation (not cantilevered)
Lithium disilicate - single units or FPD’s have higher success rates?
Single units have higher (96% at 11 vs 50-89% at 3-6)
Which has a higher Weibull Modulus (zirconia or lithium disilicate)? What does this mean?
Lithium disilicate has higher Weibull modulus (more consistent material strength)
What are the three phases of zirconia? Which is the strongest?
- Monoclinic
- Tetragonal (strongest)
- Cubic (weakest)
Which of the three phases of zirconia is the most esthetic?
Cubic (but also the weakest) Has the highest amount of ytria
Phase transformation of what phases of zirconia help reduce the propagation of cracks?
From tetragonal to monoclinic (4% larger)
What is the biggest complication with PFZ’s?
Veneer chipping
What are three factors to prevent veneer chipping?
- Anatomic framework
- Thermal diffusivity (rate of heating/cooling)
- Coefficient of thermal expansion
Is Zirconia wear a concern?
Not so far
How long do you HF acid etch silica-based ceramics?
- Feldspathic
- Lithium disilicate
- Which one is shorter and why?
- Feldspathic - 60 sec
- Lithium disilicate - 20 sec
- Etch removes glass matrix and lithium disilicate has less glass / more filler
What are the two methods to prepare polycrystallines for cementation?
- Air particle abrasion with aluminum oxide or Rocatec or Coject
- MDP silane/primer
