Final review Flashcards
A parallel post focuses its stress where?
-Apically
Where does a tapered post focus its stress?
-Coronally
Why would you put a cast post and core on a tooth?
-More than 1/2 of the coronal tooth structure is missing
Would you ever do a pre fabricated post if 3/4 of the coronal crown is missing in other words if 1/4 of the crown remains?
-No
What can you do with a prefabricated post to help give you retention?
-Ferrule (2 mm in the minimum height for an effective ferrule)
Does the surface texture of the intaglio surface have an effect on your retention?
Yes ( its needs to roughened and etched to improve)
Does a roughened tooth preparation have an effect on your retention?
-No
It is absolutely critical that the two members of the half member articulator to be parallel?
-No they can diverge, but you don’t want them to converge
What are the symptoms of a cracked tooth?
- Pressure sensitive teeth
- Cold sensitivity
- Some inconsistentsy with symptoms
What is the ultimate treatment for a partially cracked tooth?
-Full coverage crown
What cusps do you more commonly find cracks in?
More common on non functional cusps than on functional cusps
What is an advantage of using gypsum bonded investments?
-It is a smoother finish, but you can’t heat them up as hot as phosphate investments
What keeps investments from burning up?
-Refractory materials usually quartz
Can you cool your investment molds and heat them up again before you cast them?
-No because the material will break down, it has to be done in one step
What does the addition of palladium do to the color of gold?
-Makes it white
What does that addition of copper do to gold?
-Makes it more yellow
With a broken arm casting machine why are the margins placed to the right or clockwise?
-The flow goes in a clockwise direction because the arm spins in a counter clockwise direction
When an existing crown comes off of a tooth where is the most common failure interface?
-The intaglio surface of the crown (most common failure point on a crown)
What are the three types of cements?
- Esthetic
- Self adhesive
- Adhesive
What is a self adhesive resin cement that is at the UUSOD?
-Rely X unicem
Can you strengthen Rely X unicem by curing it with a light?
-Yes (the light enhances the polymerization linkage it also enhance the compressive strength)
What two properties of cements help improve retention and resistance of cements?
- Increased Compressive strength
- Higher elastic modulus