Lecture 4

Question 1

4 principles of preventing restoration wear

Answer 1

1. minimize sliding contacts
2. establish anterior guidance
3. having opposing contacts in same material
4. control parafunction

Question 2

the occlusal contact should be at least ____mm from metal-porcelain junction

Answer 2

1.5

Question 3

glass will adhere to metal when?

Answer 3

if the metal is clean and gas-free and if it is covered with adherent oxide and temperature raised to where oxide is partially dissolved into the glass

Question 4

what is the reason if there is adhesive failure at the porcelain-metal interface

Answer 4

oxide layer is missing

Question 5

what is the reason if there is adhesive failure at metal oxide-metal interface

Answer 5

contaminated metal

Question 6

what is the reason if there is adhesive failure at the porcelain-metal oxide interface

Answer 6

contaminated metal oxide

Question 7

what is the reason if there is cohesive failure in porcelain

Answer 7

fracture in porcelain (maximum strength)

Question 8

what is the reason if there is cohesive failure in metal oxide

Answer 8

excessive oxidation (fracture in oxide layer)

Question 9

what is the reason if there is cohesive failure in metal

Answer 9

trick question (this does not actually happen)

Question 10

insufficient porcelain thickness may cause ____ problems and may be due to what?

Answer 10

• esthetics

- due to under-reduced prep or excessive metal thickness

Question 11

the metal thickness of a metal-porcelain FPD needs to be what?

Answer 11

0.3mm thick

Question 12

the metal-porcelain junction should be ___ degrees

Answer 12

90