values we need to memorize

Question 1

flexural strength requirement for polymer based type 1 (occlusal, self cure, dual cure) type 2 (occlusal and luted) , type 2 ( other)

Answer 1

type 1 – 80

type 1 - class 2 –> 100

type 2 - 50

Question 2

flexural strength requirement for monolithic ceramic single unit anterior

Answer 2

50

Question 3

flexural strength requirement for monolithic single unit anterior or posterior prosthesis

Answer 3

100

Question 4

flexural strength requirement for three unit NOT involving molar

Answer 4

300

Question 5

flexural strength requirement for three unit involving molar

Answer 5

500

Question 6

flexural strength requirement for monolithic ceramic of FOUR OR MORE UNITS

Answer 6

800

Question 7

which materials are tough? which are low toughness?

Answer 7

high – fiber reinforced material, zirconia

low tough – porcelain glass

Question 8

non-resiliant materials and resiliant

Answer 8

non– pure copper

high resiliance - spring steel

Question 9

units in fracture toughness

Answer 9

MPa * m^1/2

not meters squared but square root

Question 10

K1c?

Answer 10

type 1 shear critical stress intensity factor

higher value correlates to better fracture resistance

Question 11

materials usually test higher with compressive or tensile force?

Answer 11

Compressive

Question 12

tensile and compressive strength of porcelain

Answer 12

tensile - 65

compressive - 149

Question 13

tensile and compressive strength of amalgam

Answer 13

tensile - 124

copressive - 318

Question 14

tensile and compressive strength of composite resin

Answer 14

tensile - 140

compressive 237
*high

Question 15

tensile and compressive strength of dental gypsum

Answer 15

tensile - 60

copressive - 81

Question 16

compressive strength of enamel

Answer 16

384

Question 17

T/F Zirconia has a high mean flexural strength

Answer 17

True – it is resistant to crack propagation

- good for uses in the posterior

Question 18

when doing a PFM if the preparation is too thin will the final product look overcontoured or grey?

Answer 18

BOTH – if dont prep enough the restoration will be too bulky and metal will also shine through - looking grey

Question 19

importance of condensation

Answer 19

water removal and then can have more particle packing - better bonding between

Question 20

vacuum sintering?

Answer 20

gas bubbles escape via grain boundaries and the vacuum will reduce the bubble size

so the vacuum helps to get the remaining air out of porcelain and make it more dense

improves the translucency and strength

Question 21

strength and translucnency are affected by?

Answer 21

1. firing procedures

2. condensation / powder packing

Question 22

three bonds in PFM crown

Answer 22

1. shrinkage stress
   - as shrinks grabs onto metal
2. mechanical interlock
   - rough surface to increase adhesion
3. chemical bonding
   - oxide layer

Question 23

what if there is a thermal coeffiecient mismatch?

Answer 23

failure of the bond

Question 24

major way to improve materials

what is result

Answer 24

through microstructure

prevent crack growth and fracture

Question 25

problems with porcelain

Answer 25

1. brittle and porous 2. shrinkage of 10/15% linearly and 30/40% volumetric - deformation 3. weak - metal framework is required making translucency harder to obtain

Question 26

devitrification?

Answer 26

seen with PFM's porcelain - can turn green color

Question 27

dispersion is a way to?

Answer 27

increase strength

Question 28

dispersion strengthening?

Answer 28

adding a crystalline phase to the glass - glass ceramics - aluminous porcelain to get - crack deflection - energy absorption

Question 29

heat treating?

Answer 29

can do this with glass - increase the compressive strength - with heat you will get separaion and then can fill this with crystals - helping stop craack propagation

Question 30

three major benefits seen with smaller particle size

Answer 30

1. stronger 2. low wear to opposing dentition 3. improved polishing and surface finish

Question 31

factors affecting the ware

Answer 31

1. hardness 2. crystal size 3. surface finish - polish - stain - glaze 4. environment

Question 32

processing of ceramics now (standards)

Answer 32

40-80 icrons powder size colloidal processing

Question 33

T/F polishing can increase flexural strength of veneering porcelains

Answer 33

TRUE -- also increases the fracture resistance of the ceramic

Question 34

toughening does what? general

Answer 34

improves ceramics

Question 35

how does toughening improve ceramics?

Answer 35

Surface compression - work hardening - glazing - ion exchange

Question 36

does staining improve strength?

Answer 36

NOT WHEN DONE ALONE -if you just do this you will be left with a rough surface

Question 37

what is staining?

Answer 37

application of a surface colorant and uses metal oxide and some glass

Question 38

polish - general

Answer 38

smooth surface - defect elimination

Question 39

self glaze?

Answer 39

rely on 'melting glass' in the porcelain

Question 40

over glazing?

Answer 40

apply a separate glass powder, may further improve strength

Question 41

glaze - general

Answer 41

melt glass and can strengthen and can also protect the surface stain but if do not polish this - it can ware away and then left with defects

Question 42

how long would glass glaze last?

Answer 42

2-4 years

Question 43

glazing of the porcelain can improve flexural strength by?

Answer 43

creating comopressive stress on the surface

Question 44

staining is designed for? what do you have to make sure?

Answer 44

designed to fire on a RANGE OF MATERIALS - specific cycle dependent on porcelain materials must make sure to calibrate furnace - misleading firing temps

Question 45

color staining lasts usually?

Answer 45

3 years

Question 46

if you only stain? if you stain and glaze?

Answer 46

only stain - rough stain and glaze -- glaze will ware off and be left with roughness so MUST ALWAYS POLISH FIRST

Question 47

What can the overglaze accomplish?

Answer 47

STRENGHTENING - surface compressive stress - defects filled - lower the CTE - protect color stability