Quiz review Flashcards
How is the most efficient way to adjust zirconia?
-Fine diamond (don’t use a course diamond) the coarsest you would use is a medium diamond
How much tooth structure is missing if a build up is necessary?
-1/2 or more coronal tooth structure
What is the most significant factor in long term success when it comes to teeth restored with build ups?
-The amount of coronal tooth structure remaining
What is a strengthening material of ceramics?
-LEucite
Who produces most of the zirconia powder?
-Toso corporation (quality control)
What is transformation toughening?
-When a crack begins to form in zirconia and induces a crystalline phase change at the crack
What is the phase of zirconia used for strength and toughness?
-Tetragonal
The damage of zirconia with a crack changes the zirconia from the tetragonal phase to what phase?
-Monoclinic
Why is it critical that the abrasive to adjust zirconia is harder than the zirconia itself?
-Because it won’t cause the phase transformation from heating it up
Is acufilm thicker or thinner than madam butterfly?
-Thinner
What is the advantage of madam butterfly?
- Shows relative intensities
- You can mark the same spot on the madam butterfly multiple times
When you are adjusting your proximal contacts what is the process?
-Start with a medium at first but don’t adjust it right to the perfect contact because then when you polish it won’t be perfect anymore
What do they used to stabilize ceria zirconia
-Alumina nanocomposite (aluminum oxide)
In the green state how is zirconia machined?
-Soft machined
How is lithium disilicate fabricated?
- Pressed
- Machined (hard machine)
What do build ups accomplish?
- They enhance the connection to the tooth structure
- Minimize the amount of restorative material
- Serve as a thermal insulator
- Serve as a chemical barrier
What is the other factor that determines the success of restorations?
-Occlusion is favorable (eliminate lateral load make the forces axially)
Why don’t we just put pins in all the time?
- Anatomy of the tooth
- Pins can cause iatrogenic failure
What are the disadvantages of using composite as a core material?
- There is higher moisture absorption
- Has a higher coefficient of thermal expansion (when exposed to temperature changes in the mouth it will expand and contract more)
- These can be neggated with a nice restoration over the core
What causes amalgam to expand after it is set?
-zinc
If you do a buildup in a most environment what material would you use?
-Zinc free amalgam
Can you use a chamfer for a lithium disilicate restoration?
-No
Is it easier to put a lip at the margin with a chamfer or a rounded shoulder?
-Rounded shoulder
What cement should you use for a post?
-Rely X unicem
What is the only ceramic that you can use a chamfer margin for?
-Zirconia
