Noble Metal Alloys Flashcards
Definition of “Noble” in Dentistry
ADA specified, minimum ___ by ___ - lowest limit of “__ ___” present in a noble metal alloy
Less than 25% - ____ metal alloy
ADA specified, minimum 25% by weight - lowest limit of “noble metal” present in a noble metal alloy
Less than 25% - base metal alloy
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
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
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
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
Typical Elements
Major Cu Ag Pt Ga Au Pd Zn I__
___
____
____
____
____
___
____
____
Minor
____ _____
Major
ngold (Au), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), zinc (Zn), gallium (Ga), indium (In)
Minor
iridium (Ir), ruthenium (Ru)
Noble Metals
Densities 12 – 13 g/cm3
___ ____ ____
Densities 19 – 23 g/cm3
___ ___ ___ ___
Densities 12 – 13 g/cm3
nRuthenium, rhodium, palladium
Densities 19 – 23 g/cm3
nOsmium, iridium, platinum, gold
Gold
___, ___ , ___
Rich ___ color
___ strength
Must be alloyed with___, ___ ,___ for ___
Soft, malleable, ductile
Rich yellow color
Low strength
Must be alloyed with copper, silver, platinum for strength
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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___
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
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
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
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
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
Pd-Cu-Ga :
really good metal to put ____ on.
It ___ well
It ____ well
Porcelain bonded to it beautifully
Pd-Cu-Ga : really good metal to put porcelain on.
It cast well
It finished well
Porcelain bonded to it beautifully
Ag-Pd
High____ alloys for porcelain are difficult to keep from ____
Porcelain can green on you.
He stayed away from this
Ag-Pd
High silver alloys for porcelain are difficult to keep from greening.
Porcelain can green on you.
He stayed away from this
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
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
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.
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.
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
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
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
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
