Porcelain/ceramics

Question 1

why do you add metal oxides to porcelain?

Answer 1

mimic natural tooth shades

Question 2

Ir/Ni

Answer 2

brown

Question 3

Cu

Answer 3

green

Question 4

titanium

Answer 4

yellow brown

Question 5

cobalt

Answer 5

blue

Question 6

manganese

Answer 6

lavender

Question 7

low fusing porcelain has – glass modifiers

Answer 7

a lot

Question 8

low fusing porcelain: a lot of glass modifiers reduce –

Answer 8

crosslink with silicate

Question 9

what is the melting temp of low fusing porcelain

Answer 9

low (850-1100C)

Question 10

compare low fusing and high fusing porcelain strength

Answer 10

low fusing is weaker and less stable

Question 11

which fusing type is more soluble in oral environment

Answer 11

low fusing

Question 12

what is the thermal expansion for low fusing porcelain?

Answer 12

higher than high fusing

Question 13

when would you use a low fusing porcelain?

Answer 13

veneer for a metal in PFM restorations

Question 14

– is through porcelain layer which is a metal oxide

Answer 14

chemical bonding

Question 15

chemical bonding is ionic bond bond between ceramic and –

Answer 15

oxide layer on metal

Question 16

chemical bonding: – before you add porcelain

Answer 16

heat metal in furnace

Question 17

thermally induced stress for –

Answer 17

compression fit

Question 18

describe thermal expansion for compression fit

Answer 18

thermal expansion of ceramic < metal

Question 19

metal –more during cooling

Answer 19

contracts

Question 20

ceramic more attracted to metal –

Answer 20

irregularities

Question 21

metal ceramic combination: coefficient of – of ceramic slightly lower than metal

Answer 21

expansion

Question 22

development of residual compressive stresses reduces – and – by neutralizing developing tensile stress

Answer 22

ceramic crack potential

tensile stresses

Question 23

mismatch of coefficient of expansion –>

Answer 23

crazing, ceramic fracture, debond from metal

Question 24

requirements of porcelain in PFM

Answer 24

• lower firing temp than melting temp of metal coping

- slightly lower thermal expansion coefficient than metal

Question 25

lower firing temp than melting temp of metal coping –>

Answer 25

avoid overheating metal framework

Question 26

slightly lower thermal expansion coefficient than metal –>

Answer 26

provide compressive stress

Question 27

add – to provide compressive stress

Answer 27

glass modifiers

Question 28

– is much stronger than conventional ceramic

Answer 28

core ceramic

Question 29

alumina reinforced porcelain is – embedded with alumina particles

Answer 29

feldspathic porcelain

Question 30

alumina reinforced porcelain prevents –

Answer 30

crack propagation

Question 31

alumina reinforced – strength than feldspathic

Answer 31

higher

Question 32

– is opaque and needs dentine and enamel shades

Answer 32

alumina reinforced porcelain

Question 33

development of residual compressive stresses –> residual tensile stresses in metal = no – due to their high tensile strength

Answer 33

danger of metal failing

Question 34

the difference of 0.5 X 10^-6 in thermal expansion develops – within porcelain

Answer 34

residual compressive stress

Question 35

the difference of 0.5 X 10^-6 in thermal expansion develops – within metal

Answer 35

residual tensile stress

Question 36

feldspathic porcelain is used to construct –

Answer 36

conventional PJC

Question 37

types of ceramic

Answer 37

feldspathic, alumina-reinforced, glass-infiltrated

Question 38

alumina content of alumina-reinforced porcelain

Answer 38

40-50%

Question 39

compare strength of alumina-reinforced and feldspathic

Answer 39

alumina = 120 MPa
feldspathic = 60 MPa

Question 40

applications of alumina reinforced

Answer 40

inlays, onlays, low stress crown

Question 41

add glass modifiers –> thermal coefficient

Answer 41

lower

Question 42

development of residual compressive stress –> Residual tensile stresses in metals: No danger of metal failing due to their–

Answer 42

high tensile strength