Brainscape's Knowledge GenomeTM

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


See full index

AU17 - Dental Materials 3 Final > Dental Alloys > Flashcards

Dental Alloys Flashcards

1
Q

True or False: Nobel metals form stable oxides at room temperature.

A

FALSE

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

There are ___ noble metals.

A

7

gold, platinum, palladium, iridium, ruthenium, rhodium, osmium

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

True or False: Silver is a noble metal.

A

FALSE, it forms black AgS in the oral environment

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

Precious metal classification is based upon _____.

A 
metal price
(not electrochemistry)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

True or False: Relatively common metals can become precious if very high purity is acquired.

A

True

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

True or False: 22karat gold was previously used for dental restorations.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

True or False: we now use lower-gold compositions than previously (1930s).

A

True

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

True or False: There are Types 0-6 for dental casting alloys.

A

False, Types 0 to 5

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

The current standard for dental casting alloys is ISO _____.

A

22674

do we need to know this!?

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

According to ISO Standard 22764, what are the mechanical property requirements for alloys?

A
  • 0.2% offset yield strength minimum (Types 1-5)
  • minimum percentage elongation after fracture (Types 1-5)
  • minimum Young’s modulus is specified only for Type 5
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

____ - stress per unit amount of elastic strain (higher value = less deflection for long span frameworks)

A

elastic modulus

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

_____ - amount of stress for designated small amount of permanent strain (typically 0.1%)

A

yield strength

must by sufficient for PFM restorations so that there is no deformation upon functional force

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

_____ is the amount of permanent deformation at fracture

A

ductility

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

True or False: Ductility is less important for metal-ceramic restorations since porcelain is brittle

A

True

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

_____ - generally corresponds to strength

A

Hardness (wear can occur from an alloy if its Vickers hardness is greater than that of enamel ~350)

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

True or False: Burnishability is a characteristic considered for alloy selection

A

True

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

In classification of casting alloys, which type is very low stress bearing?

A

Type 0

one surface inlays, veneers

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

Which casting alloy type is used for RPD frameworks?

A

Type 4

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

Which casting alloy type is used for thin RPD frameworks?

A

Type 5

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

Going from Type 1 to Type 5, there is a(n) _____in yield strength and hardness.

A

increase

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

Going from Type 1 to Type 5, there is a(n) _____ in ductility.

A

decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Going from Type 1 to Type 5 casting alloys, there is a(n) ____ in ease of adjustement and burnishability.

A

decrease

23
Q

Midas Reduced-Gold Alloy (Jelenko) Type 3/4 is composed of ____ gold.

A

46%

24
Q

Modulay Type 2 Gold Alloy is ____ gold.

A

77%

25
Q

Which gold alloy is used in college dental clinics?

A

Argenco Y+
cheap bastards… 2% gold
yellow shade from PdIn

(previously used midas ~50%)

26
Q

High-Noble Metal = ___-based
Nobel Metal = ____- based
Base Metal = ____-based

A

high =gold
nobel = Palladium
base = nickel

27
Q

True or False: High density porcelain alloys are favorable.

A

False, lower density preferred

28
Q

True or False: Fixed Partial Dentures fabricated from Au-Pd or Au-Pd-Ag will be more resistant to masticatory forces than those fabricated from Au-Pt-Pd.

A

True

29
Q

True or False: Palladium alloys are more technique sensitive than gold alloys. Why?

A

True

Palladium has a higher melting range and a greater tendency for gas incorporation in molten alloy

30
Q

True or False: Price volatility of palladium has been and still is a concern.

A

False, it was but not anymore

31
Q

Reports have been filed regarding _______ problems with Pd-Cu-Ga, but no problems arise from the alloy Freedom Plus.

A

bio compatibility (allergy)

32
Q

What is the most important feature of conventional base metal alloys?

A

much lower unit cost

33
Q

True or False: Conventional base metal alloys require experienced dental labs.

A

True, technique sensitive

34
Q

Which type of alloy (base metal) is favored for metal ceramic restorations?

A

Ni-Cr

35
Q

Which base metal alloy is used for patients with a nickel allergy?

A

Co-Cr

allergy =No-Cry=Co-Cr

36
Q

True or False: High gold alloys are beneficial for multi-unit restorations.

A

False, expensive and undergo dimensional changes

37
Q

True or False: Porcelain “greening” is a concern for Pd-Ag alloys.

A

False, problem was corrected with better furnaces and porcelain composition

38
Q

Which alloy is considered the “best compromise” for cost, properties and ease of manipulation?

A

Gold Palladium
(Au-Pd)

(Gold and its Pal)

39
Q

What is the purpose for Be in Ni-Cr alloys?

A

to lower fusion temperature (easier to cast) and improve bonding

40
Q

What is the harm in casting with Be?

A

Be has an adverse effect on the lungs; fumes during casting must be properly ventilated

41
Q

True or False: Patient allergies must be considered prior to alloy selection.

A

true

42
Q

What gives Argistar Yellow LF its yellow color?

A

combination of Pd and Indium

43
Q

What are the conventional base metal alloys used for RPD frameworks?

A

cobalt-chromium
nickel-chromium
cobalt-chromium-nickel

44
Q

True or False: Titanium alloys have a low strength:weight ratio.

A

False, HIGH strength to weight

45
Q

True or False: comparing gold to base metal RPD alloys, there is little difference in yield strength and ductility.

A

True

46
Q

Which difference is most important between gold and base metal RPD alloys?

A

modulus of elasticity is high for base metals
(the amount of deflection allowed before breakage)
-deflection for base metal alloys is HALF that of gold

47
Q

What are the advantages to using base metal alloys instead of gold for RPD frameworks?

A
  • cost
  • lower density (can make it thinner because its harder)
  • high elastic modulus
  • high yield strength
  • corrosion resistant
48
Q

Base metal alloys have excellent corrosion resistance from _______ surface films.

A

chromium oxide

49
Q

What are the disadvantages of base metal alloys for RPD frameworks?

A
  • limited ductility (fracture during clasp adjustment)
  • wear of tooth due to VHN >350
  • need for special equipment in casting
50
Q

The newest technology involves _____ sintering (additive manufacturing).

A

laser

51
Q

Which alloy is used in laser sintering?

A

Cobalt-Cromium

52
Q

In laser sintering, a laser scans across a bed of _____ with _____ at specific sites.

A

powder

melting (fusing particles)

53
Q

True or False: The large Phenix Dental System claims to be capable of producing 200 fixed restorations in 5 hours.

A

True

almost as fast as our lab

AU17 - Dental Materials 3 Final (6 decks)

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