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Biomaterials > Noble Metal Alloys > Flashcards

Noble Metal Alloys Flashcards

1
Q

Definition of “Noble” in Dentistry

ADA specified, minimum ___ by ___ - lowest limit of “__ ___” present in a noble metal alloy

Less than 25% - ____ metal alloy

A

ADA specified, minimum 25% by weight - lowest limit of “noble metal” present in a noble metal alloy

Less than 25% - base metal alloy

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2
Q

Noble Metals

Retain ____ in ___ air

React with ___ to form ____

Resist ___, ___, ____ during____, ___, ____ and in the mouth

They look shiny wet or dry

Should be able to be brought back to same polishability very easily

A

Retain surface in dry air

React with sulfur to form sulfides

Resist oxidation, tarnish and corrosion during heating, casting, soldering and in the mouth

They look shiny wet or dry

Should be able to be brought back to same polishability very easily

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3
Q

Ideal Properties of
Noble Alloys

____ ____ range, ____ solidus-liquidus range

Adequate ____, ____, ____

Resistance to ____

____ cost

It’s a solid and then when you get to a certain T it melts very ____

Elongation: ability to ____ and ____ it to adapt it to the tooth

Low cost does not fit most noble alloys

A

Low melting range, narrow solidus-liquidus range

Adequate strength, elongation, hardness

Resistance to corrosion

Low cost

It’s a solid and then when you get to a certain T it melts very quickly

Elongation: ability to deform and burnish it to adapt it to the tooth

Low cost does not fit most noble alloys

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4
Q

Typical Elements

Major Cu Ag Pt Ga Au Pd Zn I__

___
____
____
____
____
___
____
____

Minor

____ _____

A

Major

ngold (Au), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), zinc (Zn), gallium (Ga), indium (In)

Minor

iridium (Ir), ruthenium (Ru)

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5
Q

Noble Metals

Densities 12 – 13 g/cm3

___ ____ ____

Densities 19 – 23 g/cm3

___ ___ ___ ___

A

Densities 12 – 13 g/cm3

nRuthenium, rhodium, palladium

Densities 19 – 23 g/cm3

nOsmium, iridium, platinum, gold

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6
Q

Gold

___, ___ , ___

Rich ___ color

___ strength

Must be alloyed with___, ___ ,___ for ___

A

Soft, malleable, ductile

Rich yellow color

Low strength

Must be alloyed with copper, silver, platinum for strength

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7
Q

Platinum

Color? ___ ___

___ ___ ___

Hardness similar to ___

___ melting range

When you talking about using a high noble metal and work with ____ like with PFM

If you want to use gold, you have to alloy it with platinum, otherwise the T at which you fuse porcelain to metals are too ____ for gold to withstand. Gold will melt, deform. We had Pt to gold to use it with porcelain

A

Bluish-white

Tough, ductile, malleable

Hardness similar to copper

High melting range

When you talking about using a high noble metal and work with porcelain like with PFM

If you want to use gold, you have to alloy it with platinum, otherwise the T at which you fuse porcelain to metals are too high for gold to withstand. Gold will melt, deform. We had Pt to gold to use it with porcelain

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8
Q

Palladium

____color (____ than platinum)

____ by weight changes alloy color to ___

Densit ____ than ___ or ___

Used extensively in dental alloys

Absorbs ___ ___

When you add 10% by weight it becomes a light alloy. No longer gold

Negative: absorbs H gasà can cause ___ and other problems. Esp if you are pouring porcelain on it. H gas can ___ it and porcelain will mess up

A

White color (darker than platinum)

n>10% by weight changes alloy color to white

Density lower than gold or platinum

Used extensively in dental alloys

Absorbs hydrogen gas

When you add 10% by weight it becomes a light alloy. No longer gold

Negative: absorbs H gasà can cause pittings and other problems. Esp if you are pouring porcelain on it. H gas can contaminate it and porcelain will mess up

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9
Q

Iridium, Ruthenium, Rhodium

Used in small amounts as ____ ____

Very____ melting points – do not ____ while ____, serve as ___ ___

Whats a grain refiner: when you melt metals and then let them solidify, they solidify by hardening around little centers called grain refiners

GR don’t melt when you are heating alloy up so they are center for other metals to form their ___ ____ around

A

Iridium, Ruthenium, Rhodium

Used in small amounts as grain refiners

Very high melting points – do not melt while casting, serve as nucleating centers

Whats a grain refiner: when you melt metals and then let them solidify, they solidify by hardening around little centers called grain refiners

GR don’t melt when you are heating alloy up so they are center for other metals to form their crystalline structure around

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10
Q

Base Metals in Noble Alloys

Silver

___ and ____ than gold

___ than copper

____ melting point of ___ and ___

____ easily - considered a base metal in dentistry due to its severe tarnish caused by foods containing ___ compounds.

___ ___ in ___ state,causing ____

In dentistry, silver is considered a base metal

Tarnishes easily - considered a base metal in dentistry due to its severe tarnish caused by foods containing sulfur compounds.

This is why its considered a base metal

Added to alloys for strength

It will lower the melting point

Ag is what helps your alloy melt when you are using a Ag/Au allloy

Problem: Captures O2

When it does and you’ve over heated it, the casting will be all pitted

A

Silver

nStronger and harder than gold

nSofter than copper

nBelow melting point of copper and gold

nTarnishes easily - considered a base metal in dentistry due to its severe tarnish caused by foods containing sulfur compounds.

nCaptures O2 in molten state,causing pits

In dentistry, silver is considered a base metal

Tarnishes easily - considered a base metal in dentistry due to its severe tarnish caused by foods containing sulfur compounds.

This is why its considered a base metal

Added to alloys for strength

It will lower the melting point

Ag is what helps your alloy melt when you are using a Ag/Au allloy

Problem: Captures O2

When it does and you’ve over heated it, the casting will be all pitted

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11
Q

Copper

____, ____

____ in color

nAdds reddish color and ____ to alloy

____ melting point in ____-based alloys

Palladium melts at higher Temp also

For porcelain, sometimes they add Pd instead of Pt bc Pd is less expensive than Platinum

A

Copper

nMalleable, ductile

nRed in color

nAdds reddish color and hardness to alloy

nLowers melting point in palladium-based alloys

Palladium melts at higher Temp also

For porcelain, sometimes they add Pd instead of Pt bc Pd is less expensive than Platinum

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12
Q

Zinc

____ agent – O2 scavenger

Color?

___ easily

____

___ density

Counter acting of Silver!

Instead of O2 all going into the Au, the Zn grabs it and holds onto it and helps to protect the other metals

Helps to protect the other metal

Don’t want to use a lot of it in any type of alloy

A

Zinc

nDeoxidizing agent – O2 scavenger

nBlue-white

nTarnishes easily

nBrittle

nLow density

Counter acting of Silver!

Instead of O2 all going into the Au, the Zn grabs it and holds onto it and helps to protect the other metals

Helps to protect the other metal

Don’t want to use a lot of it in any type of alloy

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13
Q

Indium

___tarnish, ___ melting point, used to create ___ color in palladium alloys

Tin

nIncreases ____ and ____

Gallium

nCreates ___necessary for ____ bonding to alloys

Gallium allows oxides to form which allow the Porcelain to fuse to metal

A

Indium

nLow tarnish, low melting point, used to create yellow color in palladium alloys

Tin

nIncreases hardness and brittleness

Gallium

nCreates oxides necessary for porcelain bonding to alloys

Gallium allows oxides to form which allow the Porcelain to fuse to metal

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14
Q

Types of High-Noble Alloys – (Old ADA Classification)

Type I - ___ subject to only ___stress

Type II - most ___ ___

Type III - ____, ___ three-quarter crowns, ___ abutments, ____ ___ ___

Type IV - cast ____ with clasps, ___-cast ___ bridge, __ ___ crowns

Type was based on___ and ___ content

2 and 3 were___ ___ and ___ ____

Most of what you will see in patients is Type___

A

Types of High-Noble Alloys – (Old ADA Classification)

Type I - inlays subject to only slight stress

Type II - most cast inlays

Type III - crowns, thin three-quarter crowns, bridge abutments, precision-fitting inlays

Type IV - cast RPD with clasps, precision-cast fixed bridge, three-quarter crowns

Type was based on gold and platinum content

2 and 3 were high gold and high Pt

Most of what you will see in patients is Type 3

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15
Q

Carat and Fineness

Carat refers to gold content in units of ____- 18k is 75% gold.

Fineness refers to parts of gold per _____parts of ____, 18k is 750 fine.

Some sauters are listed this way

Both systems are used ____ in Dentistry, but are widely used in the jewelry industry.

___ carats in solid gold

A

Carat and Fineness

Carat refers to gold content in units of 1/24 - 18k is 75% gold.

Fineness refers to parts of gold per 1000 parts of alloy, 18k is 750 fine.

Some sauters are listed this way

Both systems are used little in Dentistry, but are widely used in the jewelry industry.

24 carats in solid gold

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16
Q

ADA Classification

High Noble

Noble metal content >____ wt%, AND

___content > ___%

Au-Ag-Pt

Au-Cu-Ag-Pd-I

Au-Cu-Ag-Pd-II

Noble Metal

Noble metal content >__%, but less than ___%

No ___ requirements (can have 0 gold)

Au-Cu-Ag-Pd-III

Au-Ag-Pd-In

Pd-Cu-Ga

Ag-Pd

Predominately Base Metal

Noble metal content <___%

Probably will have 0

Types I-IV Classification

Still used, but based on___ ___ and ____ rather than ___

Type I – ____elongation,___stress environments

Type IV – ___ stress, i.e. long span, fixed partial dentures.

Can have high ___, ___, ____

Can have Type I high noble or Type I noble

A

ADA Classification

High NobleNoble metal content > 60 wt%, AND

gold content > 40%

Au-Ag-Pt

Au-Cu-Ag-Pd-I

Au-Cu-Ag-Pd-II

Noble Metal

Noble metal content >25%, but less than 60%

No gold requirements (can have 0 gold)

Au-Cu-Ag-Pd-III

Au-Ag-Pd-In

Pd-Cu-Ga

Ag-Pd

Predominately Base Metal

Noble metal content <25%

Probably will have 0

Types I-IV Classification

Still used, but based on yield strength and elongation rather than composition.

Type I – high elongation, low stress environments

Type IV – Higher stress, i.e. long span, fixed partial dentures.

Can have high Au, Pt, or Pd

Can have Type I high noble or Type I noble

17
Q

Pd-Cu-Ga :

really good metal to put ____ on.

It ___ well

It ____ well

Porcelain bonded to it beautifully

A

Pd-Cu-Ga : really good metal to put porcelain on.

It cast well

It finished well

Porcelain bonded to it beautifully

18
Q

Ag-Pd

High____ alloys for porcelain are difficult to keep from ____

Porcelain can green on you.

He stayed away from this

A

Ag-Pd

High silver alloys for porcelain are difficult to keep from greening.

Porcelain can green on you.

He stayed away from this

19
Q

Noble Alloys – Color, Density

Au-Ag-Pt Yellow 18g/cc

Au-Cu-Ag-Pd-I Yellow 16

Au-Cu-Ag-Pd-II Yellow 14

Au-Cu-Ag-Pd-III Yellow 12

Au-Ag-Pd-In L. yellow 11

Pd-Cu-Ga White 11

Ag-Pd White 11

More ___, ___ and Less ___–>becomes more ___

High, ___ , ___, ___ they are more dense

Less gold and density decreases

A

Noble Alloys – Color, Density

Au-Ag-Pt Yellow 18g/cc

Au-Cu-Ag-Pd-I Yellow 16

Au-Cu-Ag-Pd-II Yellow 14

Au-Cu-Ag-Pd-III Yellow 12

Au-Ag-Pd-In L. yellow 11

Pd-Cu-Ga White 11

Ag-Pd White 11

More Pd, Au and Less goldà becomes more white

High, gold Pt and Pd: they are more dense

Less gold and density decreases

20
Q

Yield Strength, Elongation

Au-Ag-Pt 420 MPa 15%

Au-Cu-Ag-Pd-I 270 30

Au-Cu-Ag-Pd-II 350 30

Au-Cu-Ag-Pd-III 325 28

Au-Ag-Pd-In 300 12

Pd-Cu-Ga 1145 8

Ag-Pd 260 10

High ___ and ___: Very strong

Lose strength as you alloy it down

Higher ___ and strength comes up again

Pd-Cu-Ga (1145): Used for longer span bridges bc it held up to thre firing of the porcelains

You get ___ ____ on all of it.

A

Yield Strength, Elongation

Au-Ag-Pt 420 MPa 15%

Au-Cu-Ag-Pd-I 270 30

Au-Cu-Ag-Pd-II 350 30

Au-Cu-Ag-Pd-III 325 28

Au-Ag-Pd-In 300 12

Pd-Cu-Ga 1145 8

Ag-Pd 260 10

High Au and Ptà Very strong

Lose strength as you alloy it down

Higher Pd and strength comes up again

Pd-Cu-Ga (1145): Used for longer span bridges bc it held up to thre firing of the porcelains

You get some elongation on all of it.

21
Q

Important Properties

Melting range –

Affects ____ temperature (We want a ___-temperature burnout), type of ___ (Type of investment that we normally use for low T burnout is ____-bonded), ___ source to melt (For these we use ___-___torch)

Affects the T that we cast it at

At high MT, you need to use a different type of investment

If you heat metal to melting and don’t have investment at high enough T, you wont get good casting or it wont expand correctly

To melt the high T melting alloys you have to use __ or ___ gas

Density –___ density metals are easier to form ____ ____

They tend to ____ easier and better into the casting

Hardness

Ability to ___ permanent ____n under local ___ ___—> You can chew on it without beating it up

Affects ease of ____, affects ____ of ___ ___ or ___ ___

Ideally, you want metal and tooth to wear at same rate. Otherwise one will wear down more than the other

Most Gold Alloys don’t wear too much, just slightly more than tooth. If you grind you will wear out your gold crown

Strength

Yield strength ___ to avoid permanen ____–>This keeps them from bending when you chew

Hardening - heat treatment

Increases ___

decreases____

Elongation

Measure of ___, ____

Ability for you to burnish area that does not conform completely to the margin

A

Important Properties

Melting range –

Affects burnout temperature (We want a low-temperature burnout), type of investment (Type of investment that we normally use for low T burnout is gypsum-bonded), heat source to melt (For these we use gas-air torch)

Affects the T that we cast it at

At high MT, you need to use a different type of investment

If you heat metal to melting and don’t have investment at high enough T, you wont get good casting or it wont expand correctly

To melt the high T melting alloys you have to use propane or acetylene gas

Density –Higher density metals are easier to form complete castings

They tend to flow easier and better into the casting

Hardness

Ability to resist permanent deformation under local occlusal loads à You can chew on it without beating it up

Affects ease of polishing, affects wear of opposing restoration or tooth structure

Ideally, you want metal and tooth to wear at same rate. Otherwise one will wear down more than the other

Most Gold Alloys don’t wear too much, just slightly more than tooth. If you grind you will wear out your gold crown

Strength

Yield strength high to avoid permanent deformationàThis keeps them from bending when you chew

Hardening - heat treatment

Increases strength, decreases elongation

Elongation

Measure of ductility, burnishability

Ability for you to burnish area that does not conform completely to the margin

22
Q

Gold-Colored Metal-Ceramic Alloys

88% Au, 9% Pt

____ metal composite alloy.

___ free ____ color. (Warm gold color made the tooth look more ___)

You have to put opaque porcelain over that metal to enhance bonding and to cover the metal

You have to put thicker opaque on ____l (black) compared to CAPTEK

High ___ ____ (bc of the ___)

High ___ ___

___ properties that allow ____ (Great burnishability bc of high ___)

____ for ____ control at the ceramometal interface.

CAPTEK had a flash of desirability but has lost it

Its like a wax and infuse it with metal and you wax it onto the dye and put it in oven, process and heat it, and it actually solidifies

A

Gold-Colored Metal-Ceramic Alloys

88% Au, 9% Pt

Solid metal composite alloy.

Oxide free gold color. (Warm gold color made the tooth look more alive)

You have to put opaque porcelain over that metal to enhance bonding and to cover the metal

You have to put thicker opaque on traditional (black) compared to CAPTEK

High temperature stability. (bc of the Pt)

High abrasion resistance.

Elastic properties that allow burnishability (Great burnishability bc of high gold)

Resilience for stress control at the ceramometal interface.

CAPTEK had a flash of desirability but has lost it

Its like a wax and infuse it with metal and you wax it onto the dye and put it in oven, process and heat it, and it actually solidifies

Biomaterials (15 decks)

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