Applied Dental Materials 2 Lecture 2 (Alloys 1)

Front 1

Put these steps in order

A. Master die prep
B. Burnout
C. Casting
D. Wax pattern formation
E. Cavity/tooth prep
F. Impression of prep
G. Investment of pattern
H. Finish and delivery

Back 1

E, F, A, D, G, B, C, H

Front 2

In what year did the NBS classify gold alloys?

Back 2

1932

Front 3

In what year was the lost-wax technique developed?

Back 3

1907

Front 4

True or False, cost-effectiveness is not a consideration when selecting alloys for casting

Back 4

False, money doesn't grow on trees

Front 5

There are 6 ways to classify casting alloys, what are they?

Back 5

Use, major elements, nobility, principal elements, dominant phase system, properties and use

Front 6

Casting alloys, ADA type I-IV are base on what?

Back 6

properties and use

Front 7

Which of the 6 classification of casting alloys is the main one used by the ADA?

Back 7

nobility

Front 8

What are the three different nobilities of casting alloys?

Back 8

Noble, high noble, predominantly base metal

Front 9

How many "noble" metals are there and which one DOES corrode in the mouth? (hint: bc of this, it's not considered noble in dentistry)

Back 9

there are 8, silver is the only one that corrodes in the mouth

Front 10

Au, Pt, Pd, Ir, Os, Rh, Ru, and Ag are what category of metal?

Back 10

Noble

Front 11

PB alloys contain less than __% noble metal

Back 11

25

Front 12

Noble alloys contain > or = to __% noble metal

Back 12

25

Front 13

High noble metals contain > or = to __% gold and > or = to __% noble metals

Back 13

40, 60

Front 14

What is the website that Dr. Khajotia presented in class for looking up alloy metals?

Back 14

www.identalloy.org

Front 15

What "type" of metal alloys can be heat treated?

Back 15

type 3 and 4

Front 16

Type (1/2/3/4) is the softest alloy

Back 16

1

Front 17

The harder a metal is, the (harder/easier) it is to burnish

Back 17

harder

Front 18

Which type of alloy should be used in LOW stress situations only?

Back 18

type 1

Front 19

Type __ alloy would be suitable for a 3/4 crown

Back 19

2

Front 20

Yield strength (increases/decreases) from type 1 to type 4

Back 20

increases

Front 21

Type (1/2/3/4) contain the most gold

Back 21

1

Front 22

Type (1/2/3/4) are most easily elongated

Back 22

1

Front 23

18 karat gold would have what wt% of gold?

Back 23

75% (18/24 = .75)

Front 24

____ refers to the number of parts of gold in thousand parts of an alloy

Back 24

fineness

Front 25

An alloy with 64% gold would have a fineness of ___

Back 25

0.640

Front 26

Metal content in an alloy is now described as a (fraction/percentage) composition in the alloy

Back 26

percentage

Front 27

What is ductility?

Back 27

The ability to draw something into a wire

Front 28

Gold exibits (good/poor) corrosion resistance, (high/low) specific gravity

Back 28

good, high

Front 29

Which metal is an oxygen scavenger?

Back 29

Zinc

Front 30

What metal (under porcelain) will form the most esthetic restoration?

Back 30

gold

Front 31

platinum (softens/hardens) alloy, (lowers/raises) melting, (decreases/increases) corrosion resistance

Back 31

hardens, raises, increases

Front 32

What two metals together constitute "white gold"?

Back 32

gold and palladium

Front 33

Palladium (increases/decreases) corrosion of silver alloys, imparts a ___ color, is (more/less) expensive than platinum, and (improves/worsens) strength

Back 33

decreases, white, less, improves

Front 34

Silver (hardens/softens) the alloy, adds (gray/white) color, (increases/decreases) cost, and (does/does not) corrode easily

Back 34

hardens, white, decreases, DOES

Front 35

Zinc (improves/worsens) castability of alloy

Back 35

improves

Front 36

What metal is the principal hardener in alloy? (hint: also hardener in amalgam)

Back 36

copper

Front 37

copper adds a ___ color

Back 37

reddish

Front 38

What metal is responsible for "age-hardening"?

Back 38

copper

Front 39

Copper will (increase/decrease) corrosion resistance

Back 39

decrease

Front 40

What is the purpose of Ir and Ru metals?

Back 40

grain size refinement

Front 41

Mo and W are added to (increase/decrease) thermal expansion

Back 41

decrease

Front 42

how does copper increase hardness and strength?

Back 42

distorts gold structure causing increased dislocation pile ups and hence... increased strength

Front 43

Why do we WANT oxides on HN alloys?

Back 43

so it will bond to porcelain in an MCR restoration

Front 44

What three metals will increase potential of metal surface to form oxides in HN alloys?

Back 44

Fe, In and Sn

Front 45

The hardness, tensile stress and strength (increase/decrease) from type 1 to 4, and ductility and corrosion resistance (increase/decrease) from type 1 to 4

Back 45

increase, decrease

Front 46

Changes in properties between alloys and between soft and hard alloys is due to increase in ___ and decrease in ___ (metals)

Back 46

copper, gold

Front 47

Contraction of the metal during change from liquid to solid is called ___

Back 47

solidification shrinkage

Front 48

What is the typical % of thermal contraction in a type III alloy?

Back 48

1.5%

Front 49

True or False, thermal contraction of solid metal to room temperature does not need to be compensated for because it's not that influential

Back 49

False, you DO need to compensate if the casting is to fit onto the tooth

Front 50

Type (1/2/3/4) has the greatest casting shrinkage

Back 50

4

Front 51

When you burnish a metal, it becomes (softer/harder)

Back 51

harder

Front 52

After burnishing a margin, it becomes hardened. Why is it necessary to soften it again?

Back 52

Because you don't want it to become too brittle

Front 53

What is the purpose of the softening heat treatment?

Back 53

Re-softens hardened margins to make them less brittle

Front 54

ADA spec. # __ and __ dictate softening and hardening heat treatment

Back 54

5, 7

Front 55

softening heat treatment is also called ___, whereas hardening heat treatment is also called ___

Back 55

solution heat treatment, age hardening

Front 56

For softening heat treatment, the alloy is placed in a furnace at ___C for ___ minutes, then quenched in water (immediately/after 1 hr)

Back 56

700, 10, immediately

Front 57

A (softer/harder) alloy is easier to finish and adjust the fit of the casting

Back 57

softer

Front 58

Which if the following is the only thing that INCREASES after softening heat treatment?

a. tensile strength
b. proportional limit
c. hardness
d. ductility

Back 58

d. ductility

Front 59

For hardening heat treatment, the alloy is placed in a furnace at ___C for __ min, the allowed to cool to ___C and immediately quenched in water

Back 59

450, 30, 250

Front 60

True or false, both softening and hardening heat treatment increase ductility

Back 60

False, softening increases ductility, hardening lessens it

Front 61

Which of the following is hardening typically NOT indicated for?

a. metallic partial dentures
b. inlays
c. bridges
d. saddles

Back 61

b. inlays

Front 62

If you are going to reuse an alloy, you must melt the clean pickled scrap on a ____ block

Back 62

charcoal

Front 63

What is the purpose of adding new alloy to an alloy you want to reuse?

Back 63

restore burn-out elements

Front 64

You should add what ratio of old to new metal alloy that you want to reuse?

a. 1:1
b. 2:1
c. 1:2
d: 1:10
e. 10:1

Back 64

a. 1:1 (should be a 50/50 mix of old and new alloy)

Front 65

True or false, it's ok to mix different types and brands of alloy you want to reuse

Back 65

false

Front 66

Ag-Pd alloys contain ___% Ag, and ___% Pd

Back 66

60-72; > or = to 25

Front 67

Ag-Pd alloys with high Ag content have similar properties to type (1/2/3/4) gold alloys, but low Ag have similar properties to type (1/2/3/4)

Back 67

3, 4

Front 68

High copper content makes the restoration (more/less) susceptible to tarnish

Back 68

more

Front 69

High palladium noble metal alloys are used almost exclusively for what application?

Back 69

crown and bridges

Front 70

High palladium noble metal alloys have density (higher/lower/midway) when compared to HN gold and base metal alloys

Back 70

midway

Front 71

per ounce, high palladium noble metal alloys cost how much less than gold alloys?

Back 71

half to 1/3 as much as gold alloys

Front 72

True or false, high palladium noble metal alloys are similar in workability to gold alloys

Back 72

True

Front 73

Pd-Ag alloys contain ___% Pd and ___% Ag

Back 73

53-61, 28-40

Front 74

Pd-Ag alloys may contain traces of what two metals to add hardness?

Back 74

tin, indium

Front 75

True or false, tin and indium are added to Pd-Ag, only to increase hardness

Back 75

False, they do this, BUT they also promote formation of oxides, allowing stronger bonds to porcelain

Front 76

In order to replace expensive Pd in Pd-Ag alloys, manufacturers added more Ag in place of Pd which leads to the following issues:

(higher/lower) melting range
(increased/decreased) coefficient thermal expansion
(increased/decreased) porcelain discoloration

Back 76

lower, increased, increased

Front 77

What term refers to the greenish-yellow tint resulting from the escape of silver vapor from the alloy surface during porcelain firing?

Back 77

greening

Front 78

Greening results from the escape of ___ vapor, followed by diffusion of ___ ion onto the porcelain (hint: same answer)

Back 78

silver, silver

Front 79

What is formed within the superficial layers of porcelain when greening occurs?

Back 79

colloidal metallic silver

Front 80

Which of these accentuates greening?

a. Ag content
b. Na content of porcelain
c. # of firing cycles
d. use of vacuum during firing
e. darker porcelain

Back 80

All except e (should be LIGHTER shade of porcelain)

Front 81

Which of these helps lessen greening?

a. silver metal conditioners
b. ceramic coating agents
c. non-greening porcelains

Back 81

b and c (a should be GOLD, not silver)

Front 82

Which is more expensive, Pd-Ag or Gold alloys?

Back 82

Gold

Front 83

True or False, Pd-Ag are usually very difficult to grind and polish

Back 83

false

Front 84

Pd-Ag have good thermal compatibility with porcelains, except (low/high)-expansion porcelains

Back 84

low

Front 85

Which of these describes Pd-Ag alloys?

(low/high) specific gravity
(low/high) hardness
(low/high) elongation values

Back 85

low, low, high

Front 86

Pd-Cu alloys contain ___% Pd and ___% Cu... sometimes they contain 2% of what metal as well?

Back 86

74-80, 9-15, Au

Front 87

What might copper form that causes discoloration of Pd-Cu alloys?

Back 87

dark oxides

Front 88

How can the color staining of copper be masked with a porcelain restoration?

Back 88

adding a layer of opaque porcelain FIRST

Front 89

Pd-Cu alloys have:

(low/high) yield strength
(low/high) hardness
(low/high) elongation values
(easy/hard) to burnish

Back 89

high, high, low, hard

Front 90

True or false, Pd-Cu have good thermal compatibility with porcelain

Back 90

true

Front 91

Creep deformation is also known as ___

Back 91

SAG

Front 92

Pd-Cu tend to undergo creep deformation at (high/low) firing temperatures

Back 92

high

Front 93

What is the melting range of Pd-Cu alloy?

Back 93

1170-1190C

Front 94

True or False, Pd-Cu are the least technique sensitive alloys

Back 94

false, they are VERY technique sensitive

Front 95

Pd-Co alloys contain __% Pd and __% Co

Back 95

78-88, 4-10

Front 96

Pd-Co is the (least/most) sag resistant of all noble metal alloys

Back 96

most

Front 97

Pd-Co has moderate hardness and (low/high) ductility

Back 97

high

Front 98

True or False, Pd-Co does not contain Be or Ni

Back 98

True

Front 99

Other than Pd-Cu alloys, what other alloy forms dark oxides that can be hidden by opaque porcelain?

Back 99

Pd-Co

Front 100

Pd-Ga-Au-Ag alloys contain what % of each of these?

Back 100

Pd 75%
Au 6%
Ga 6%
Ag 5-8%

Also contain 6% In

Front 101

Pd-Ga-Au-Ag contain (dark/light) oxides

Back 101

light

Front 102

Pd-Ga-Au-Ag alloys:

(high/low) thermal expansion
(are/are not) compatible w/ low expansion porcelain

Back 102

low, are