Applied Dental Materials 2 Lecture 9 (Dental Porcelains)

Front 1

The following describes what kind of material?

amorphous, non-crystalline, vitreous, supercooled liquid

Back 1

glass

Front 2

A compound of metallic and nonmetallic elements is a ____

Back 2

ceramic

Front 3

Which of these is considered metallic?

Si
F
B
K
O

Back 3

K

(the rest are NON-metallic)

Front 4

A solid composed of a glassy matrix and one or more crystalline phases produced by controlled nucleation and growth of crystals in glass is called?

Back 4

glass-ceramic

Front 5

A ceramic consisting of glass matrix phase and one or more crystalline phases is called what?

Back 5

porcelain (feldspathic porcelain)

Front 6

True or False, all porcelains are ceramics, but not all ceramics are porcelains

Back 6

True

Front 7

a ceramic composed of a glass matrix and at least 35 vol% Al2O3 is called?

Back 7

aluminous porcelain

Front 8

a ceramic formulated to be sintered at cervical area of a metal-ceramic crown to produce an esthetic and a fracture-resistant butt-joint margin is?

Back 8

shoulder porcelain

Front 9

Which level of dental porcelains is 1300-1370C?

High-fusing
Medium-fusing
Low-fusing
Ultra-low fusing

Back 9

high-fusing

Front 10

Which level of dental porcelains is 1101-1300C?

High-fusing
Medium-fusing
Low-fusing
Ultra-low fusing

Back 10

medium-fusing

Front 11

Which level of dental porcelains is 850-1100?

High-fusing
Medium-fusing
Low-fusing
Ultra-low fusing

Back 11

Low fusing

Front 12

Which level of dental porcelains is < 850C?

High-fusing
Medium-fusing
Low-fusing
Ultra-low fusing

Back 12

ultra-low

Front 13

Which level of dental porcelains is used in porcelain crown and bridges?

High-fusing
Medium-fusing
Low-fusing
Ultra-low fusing

Back 13

low and ultra low

Front 14

Which level of dental porcelains is used in prefabricated pontics?

High-fusing
Medium-fusing
Low-fusing
Ultra-low fusing

Back 14

medium fusing

Front 15

Which level of dental porcelains is used in denture teeth?

High-fusing
Medium-fusing
Low-fusing
Ultra-low fusing

Back 15

high fusing

Front 16

What is the process of fusion of constituent components of a ceramic followed by a rapid COOLING (quenching) of the glass in cold water, resulting in material having extensive CRACKING due to thermal SHOCK?

Back 16

fritting

Front 17

What is a frit?

Back 17

The fine powder that a material is ground into after the fitting process

Front 18

The benefits of fritting porcelain includes:

(increase/decrease) firing time
(lengthen/shorten) firing cycle
(decrease/increase) drying time
(increase/decrease) shrinkage

Back 18

decrease, shorten, decrease, decrease

Front 19

What is the term for when frit is mixed with water or other vehicle and condensed thoroughly into desired shape to obtain dense packing so as to reduce firing shrinkage and porosities; condensation methods used include brush, vibration and spatulation; best condensation possible when powder particles have a range of sizes?

Back 19

condensation

Front 20

What is the term for a process of heating closely packed particles to achieve interparticle bonding and sufficient diffusion to decrease surface area or increase density of structure?

Back 20

Sintering

Front 21

Sintering is also called what?

Back 21

firing

Front 22

True or False, there is no chemical reaction involved in sintering

Back 22

True

Front 23

What type of restoration combines the strength and accuracy of cast metal with the esthetics of porcelain?

Back 23

MCR (metal-ceramic restoration)

Front 24

What are the three alternate names for an MCR?

Back 24

Also known as porcelain-fused-to- metal (PFM), porcelain veneer crown (PVC) or porcelain jacket crown (PJC)

Front 25

True or False, MCRs are stronger than most all-ceramics

Back 25

True

Front 26

"keramos" means what?

Back 26

pottery/potter

Front 27

What is the chemical formula for silica?

Back 27

SiO2

Front 28

What are the 4 isomorphs of silica?

Back 28

quartz, cristobalite, tridymite (crystalline forms), fused silica (amorphous form, very high melting)

Front 29

Which of the 4 forms of silica is NOT considered crystalline?

Back 29

fused silica

Front 30

What are the three "other" forms of silica?

Back 30

yellow sand
flint
gem stones

Front 31

Fill in the blanks:

____ sand - ____ with iron oxide impurities

flint - ______ silica

gem stones - amethyst, ____

Back 31

yellow sand - quartz with iron oxide impurities

flint - amorphous silica

gem stones - amethyst, opal

Front 32

2 other uses of silica include:

As a ___ agent

In ___ to provide transparent compound, translucent to ultraviolet radiation, resistant to ____ and ____ shock

Back 32

drying

glass, thermal, mechanical

Front 33

Feldspar melts ____ about 1150C to form new solid and liquid

Back 33

incongruently

Front 34

What are the three main components of dental porcelain?

Back 34

Feldspar, glass modifiers, coloring frit and other modifiers

Front 35

When feldspar is melted, it forms a new solid called ___ and the liquid forms a ___ on cooling

Back 35

leucite
glass

Front 36

What is the main difference between potash feldspar and soda feldspar?

Back 36

potash feldspar has K whereas soda feldspar has Na

Front 37

What is imbedded in the glassy matrix after feldspar is melted?

Back 37

leucite

Front 38

True or False, there is no feldspar left in fired porcelain

Back 38

True

Front 39

Feldspar acts as a binding ___ for quartz and clay

Back 39

flux

Front 40

When the ___ is sintered to fabricate an MCR, the (higher/lower) fusing powders flow and fuse the mass together

Back 40

frit, lower

Front 41

In Latin, flux means what?

Back 41

flow

Front 42

___ is fritted with various metal (iodides/oxides/amines) to form the glassy materials that make up dental porcelains

Back 42

feldspar, oxides

Front 43

What component of dental porcelain acts to break up silica network and lower firing temp of porcelain?

Back 43

glass modifiers

Front 44

Glass modifiers act to break up silica network and lower firing temp of porcelain, which means allow is not heated to temperatures causing ___ (known as flexural creep) of alloy

Back 44

sag

Front 45

What is the purpose of the coloring frits in dental porcelain?

Back 45

create different shades

Front 46

Frits produced by the addition of metallic oxides are typically what?

Back 46

coloring frit

Front 47

For coloring frit, Ni oxide is the color ___ and Co oxide is the color ___

Back 47

brown, blue

Front 48

What type of porcelain was originally designed as add on materials (incisal buildup, porcelain margins, repairs, etc.)

high-fusing
medium-fusing
low-fusing
ultra low-fusing

Back 48

low fusing

Front 49

What type of porcelain is used for fusing to gold-colored alloys similar to Type IV gold alloys?

high-fusing
medium-fusing
low-fusing
ultra low-fusing

Back 49

low fusing

Front 50

What type of porcelain is the newest group and us used as ceramic cores or as veneering ceramics for Ti?

high-fusing
medium-fusing
low-fusing
ultra low-fusing

Back 50

ultra low-fusing

Front 51

The oxidation rate of Ti increases markedly above ___C

Back 51

900

Front 52

What type of porcelain contains either well-distributed dispersion of small crystal particles, or few to no crystals, depending on whether the ceramic is to be used as veneer or glaze?

high-fusing
medium-fusing
low-fusing
ultra low-fusing

Back 52

ultra low fusing

Front 53

What type of porcelain typically has lower enamel wear rate than those produced by conventional low-fusing porcelains?

high-fusing
medium-fusing
low-fusing
ultra low-fusing

Back 53

ultra low-fusing

Front 54

What type of porcelain has varying expansion coefficients and may not be thermally compatible with certain ceramic core materials or metal substrates?

high-fusing
medium-fusing
low-fusing
ultra low-fusing

Back 54

ultra low-fusing

Front 55

Fill in the blank for the steps in fabricating and MCR:

Fabrication of a metal ___ or substrate

Cleansing metal substrate by __ or __ blasting

____ the metal substrate to prevent the formation of bubbles

Application of ____

Back 55

coping

air, sand

degrassing

porcelain

Front 56

The opaque layer of porcelain typically has (light/dark) oxides

Back 56

dark

Front 57

What are the three main "layers" in porcelain application?

Back 57

opaque, body/gingival, incisal/enamel

Front 58

True or False, each layer of porcelain is condensed and fired separately and in succession

Back 58

True

Front 59

What is the point of vacuum firing (or sintering) porcelain?

Back 59

to reduce the size and number of porosities

Front 60

When condensed porcelain is places in a porcelain furnace, (liquid/powder) particles are packed together with (water/air) channels around them. As the air pressure is reduced to about __% of atmospheric pressure, air around the particles is also reduced to this pressure.

Back 60

powder, air, 10%

Front 61

(continuation of previous question regarding porcelain application)

As the temperature (lowers/rises), particles sinter together and voids (disappear/remain). At temp of ~ __F below the upper firing temp, vacuum is release and pressure inside the furnace increases by a factor of __. Voids are squeezed to ___% of their original size, this reducing the overall volume of porosity by a factor of 10.

Back 61

rises, remain, 100, 10, 10

Front 62

Porcelain is supplied as a fine powder that is mixed with ___ or other vehicle and condensed into the desired form

Back 62

water

Front 63

Powder particles are of a particular distribution of sizes that produce the (least/most) dense packing when properly condensed

Back 63

most

Front 64

Proper and thorough condensation is also crucial in obtaining dense packing of powder particles, which provides two benefits: (higher/lower) firing shrinkage and (more/less) porosities in the fired porcelain

Back 64

lower, less

Front 65

Most dental porcelains (are/are not) vacuum fired. Why?

Back 65

are, to minimize porosities

Front 66

Why are porosities undesirable?

Back 66

Reduce translucency of porcelain by scattering light within porcelain which makes it appear more opaque.

Can also lower strength if porosities are extensive

Front 67

What are the two types of glaze firing?

Back 67

internal and external glazes

Front 68

(internal/external) glazes with lower fusing temperature than dental porcelains due to addition of glass modifiers. Stain are tinted/colored glazes

Back 68

external

Front 69

(internal/external) glazes produce lifelike results and are not subject to dissolution in oral fluids. However, porcelain has to be stripped completely of color or characterization is unsuitable.

Back 69

internal

Front 70

MCR alloy forms ___ during degrassing treatment or initial firing stages (if no degrassing is done)

Back 70

oxides

Front 71

What is the link between metal and porcelain in an MCR?

Back 71

oxides

Front 72

True or False, oxides are responsible for the bind between metal and porcelain in an MCR

Back 72

True

Front 73

What metal elements can be added to noble or high noble alloys to increase formation of oxides for bonding?

Back 73

In, Ga, Fe, Zn, Sn

Front 74

Base metal alloys containing Cr, Ni and Be (do/do not) readily form oxides and bond to porcelain, so oxide formation must be carefully controlled

Back 74

do

Front 75

True or False, no trace elements are added to BASE metal alloys for oxide formation

Back 75

True (but they are added to noble and high noble alloys

Front 76

alphaP is alpha of ___

(alpha = coefficient of thermal expansion)

Back 76

porcelain

Front 77

alphaM is alpha of ___

(alpha = coefficient of thermal expansion)

Back 77

alloy

Front 78

alpha of porcelain is approximately __ x 10^-6/C so it was RAISED to __ x 10^-6/C by adding what to the porcelain frit?

(alpha = coefficient of thermal expansion)

Back 78

2-4, 7-8, alkali

Front 79

alpha of alloy is approximately __ x 10^-6/C so it was LOWERED to __ x 10^-6/C by adding what two metals to Au-containing alloys?

(alpha = coefficient of thermal expansion)

Back 79

12-14, 7-8, Pt or Pd

Front 80

Optimum difference is:

(alpha of alloy) > (alpha of porcelain) by __ x 10^.6/C or less

(alpha = coefficient of thermal expansion)

Back 80

1

Front 81

Shell and Neilson (1962) determined that spontaneous fracture occurs at __ x 10^-6

Back 81

1.7

Front 82

Which of these is NOT thermally compatible under any circumstance?

(alpha of alloy) > (alpha of porcelain)

(alpha of porcelain) > (alpha of alloy)

(alpha = coefficient of thermal expansion)

Back 82

alpha of porcelain > alpha of alloy is NOT thermally compatible

Front 83

What are the most common types of failures? (list two)

Back 83

V (metal oxide-metal oxide) and IV (metal-metal oxide)

Front 84

Most dental porcelains demonstrate (high/low) hardness values

Back 84

high

Front 85

True of False, high hardness means high abrasion potential is inevitable

Back 85

False

Front 86

Abrasiveness can be minimized if the surface is ___ or (smooth/rough)

Back 86

glazed, smooth

Front 87

(vacuum/non-vacuum) fired dental porcelain can be worked to a very smooth surface for what reason?

Back 87

vacuum, almost completely free of porosities

Front 88

True or False, polishing porcelain is at least as effective as glazing in reducing roughness and abrasion potential

Back 88

True

Front 89

True or False, fluoride can attack porcelain

Back 89

True

Front 90

True or False, acidulated fluorides can etch glass matrix in porcelain

Back 90

True

Front 91

What are two examples of fluoride gels that can etch porcelain?

Back 91

1.23% acidulated phosphate fluoride (APF) and 8% stannous fluoride

Front 92

What would be considered acceptably low concentrations of stannous and sodium fluoride for us around dental porcelains?

Back 92

0.4% stannous and 2% sodium

Front 93

True or False, phosphoric acid has the most destructive effect relative to how long it's applied compared to any other dental acid

Back 93

False, it has VERY LITTLE EFFECT on dental porcelains!!!

Front 94

The longevity of MCRs is (worse/better) than all-ceramic restorations

Back 94

better

Front 95

All-ceramic restorations have (worse/better) biocompatibility and (more/less) plaque retention than MCRs

Back 95

better, less

Front 96

Emergence profiles are less likely to be over-contoured in (all-ceramic/MCRs) restorations

Back 96

all-ceramic

Front 97

the cost of all-ceramics is comprable to what type of MCR?

Back 97

HN

Front 98

Which has better esthetics, MCR or all-ceramic?

Back 98

all-ceramic

Front 99

Fill in the blank for the reasons why all-ceramic restorations are mor esthetic than MCRs:

A (wider/narrower) range of translucency and opacity can be achieved

No masking of metal ___ necessary

No exposed ___ margins are visible

finish lines can be at or slightly below gingival margins, thereby maintaining adequate ___ health and providing acceptable esthetics

Back 99

wider
oxides
metal
gingival