Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

fixed > Dental alloys for Complete veneer crowns > Flashcards

Dental alloys for Complete veneer crowns Flashcards

1
Q

Chemical properties of Gold

A

Most noble and corrosion-resistant metal
Not tarnished by air or water
Does not dissolve in HCL, H2SO4, HNO3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

MEchanical Properties of Gold

A

Most ductile and malleable metal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Problem with Gold for Dental restorations and how to fix

A

Too weak, must use other alloying elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How to etch gold

A

aqua regia (1HNO3: 3 HCl)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are nobile metals chemically

A

do not form stable oxides at room temp

Lowest tendency to lose elctrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the noble metals

A 
Gold
Platinum
Palladium
Iridium
Ruthenium
rhodium
osmium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the noble metals content of dental alloys

A

Au+Pt+Pd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Is silver a noble metal in oral envirnoment

A

NO (forms black AgS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What defines a Precious metal

A

By price, NOT electrochem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Can common metals become precious

A

Yes, when very high purity is required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a Carat

A

Parts out of 24 with pure gold, tels nothing about other elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is Fineness

A

PArts out of 1000 with pure gold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When is fineness used

A

For specification of dental solders

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is 1 pound Avoirdupois

A

16 oz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is 1 pound troy

A

12 oz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

when would you use pound troy

A

Noble metals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Ratio of pounds troy to pounds avoirdupois

A

.823 pounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

1 troy oz is how many pennyweights (dwt)

A

20 penny weights

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

1 pennyweight is how many grams

A

1.555 grams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What kind of gold used to be used in dental casting alloys

A

Coin gold and 22k gold

types I-IV high gold casting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How much gold is in todays casting

A

lower gold

22
Q

What specification of dental castinga lloys has been withdrawn

A

Historic ANSI/ADA specification No.5

23
Q

What is the current standard for dental casting alloys

A

ISO 22674 (types 0-5)

24
Q

The ability of a metal to stretch and seal a margin

A

Burnishability

25
Q

what are additional alloy selection factors

A

Cost of the metal per pennyweight
Burnishability
Solderability
Experience of the dental lab

26
Q

when to use type 0 alloys

A

Very low stress-bearing (small veneered 1 surface inlays)
Veneered crowns
metallic materials for metal-ceramic crowns produced by electroforming or sintering

27
Q

when to use type 1 alloys

A

Low stress bearing single tooth restorations ( veneered or unveneered one surface inlays, Veneered crowns

28
Q

When to use type 2 alloys

A

single tooth fixed restorations (Crowns or inlays without restriction on number of surfaces)

29
Q

When to use type 3 alloys

A

Multiple-unit fixed restorations (bridges)

30
Q

When to use type 4 alloys

A

Thin sections subject to very high forces
(RPD, clasps, thin veneered crowns, bridges with wide spans or small cross-sections, attachments, implant retained superstructures)

31
Q

When to use type 5 alloys

A

Appliances requiring combination of high stiffness and strength
(thin RPDs, parts with thin cross-sections, clasps)

32
Q

What is the trend as you go from type 0 to type 5 gold casting alloys

A

More other elements
Easier to melt
HArder to burnish and adjust

33
Q

Roll of gold in gold casting alloys

A

Provide ductility

tarnish and corrosion resistance

34
Q

Roll of Copper in gold casting alloys

A

Principle element for hardening and strength)

35
Q

How much copper has to be added for a reduction in tarnish and corrosion resistance

A

exceeding 12%

36
Q

Roll of silver in gold cast alloys

A

Counteracts effect of copper on color and substitutes economically for gold without degrading mech properties

37
Q

Roll of Platinum and palladium in gold casting alloys

A

Provides tarnish and corrosion resistance

Strength

38
Q

How much platinum and palladium can be added

A

Not much because itll raise the melting temp

39
Q

Roll of zinc in Gold casting alloys

A

OXygen scavenger during melting to minimize oxidation of other elements
improve castability and fluidity of molten alloy

40
Q

Different strucutres of AuCu3

A

disorded (fcc strucutre)

Ordered alpha prime(simple cubic strucutre)

41
Q

when does the orded alpha prime strucutre of AuCu3 form

A

below about 400 degrees celcius

42
Q

When does the Disordered structure form

A

At high temperatures (usually has a lot of gold)

43
Q

Roll of small amounts of Indium and gallium in gold casting alloys

A

Provide hardening and strengthening

44
Q

why add small amounts of iridium to gold casting alloys

A

grain refinement

45
Q

What does grain refinement do

A

Improves mechanicalproperties, composition uniformity in microstrucutre
and corrosion resistance

46
Q

Solid solution hardening is provided by what elements

A

Copper, platinum, palladium, silver and zinc

47
Q

Order hardneing is provided by

A

Copper (but a lot needed for the transition to occur)

48
Q

what allows ordering to occure

A

Slow cooling through appropriate temperature range

49
Q

what leads to a softened contion of gold casting alloys

A

Quenching leads to unordered transformtion (too fast)

50
Q

what leads to a hardened condition

A

Bench-cooling
Furnace heat treat
-ordered transformation

fixed (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions