Casting and Soldering Investments Flashcards
Casting Investment - Purpose
vUsed in Lost Wax Casting Technique
vCreates the __ ___ into which the __ __ will flow
vIn 1907 a Dentist,
Dr. William H. ___, came up with the techniques that made casting an everyday option.
vUsed in Lost Wax Casting Technique
vCreates the mold cavity into which the molten metal will flow
vIn 1907 a Dentist,
Dr. William H. Taggart, came up with the techniques that made casting an everyday option.
vOver four thousand years ago man invented the lost wax technique .
vOnce you have waxed your pattern you need a way to change it from ___ into a ___ substrate.
vOver four thousand years ago man invented the lost wax technique .
vOnce you have waxed your pattern you need a way to change it from wax into a usable substrate.
–
vIn this technique wax is placed into a medium:
v ___
v___
v___ or __ ___
vThe wax is__ __, and __ or ___ is ___, ___ or ___ into the space created by this melted wax.
–
vIn this technique wax is placed into a medium:
v sand
v mud
vceramic or casting investment.
vThe wax is melted out, and metal or glass is poured, pressed, or vacuumed into the space created by this melted wax.
v___ your pattern
v___ your pattern
v___ t the pattern
v__ __(___)
v__
v__ and __ your casting
vMake your pattern
vSprue your pattern
vInvest the pattern
vWax elimination (Burnout)
vCast
vFinish and polish your casting
vPattern is ____ -=and made ready to invest.
vPattern is created and made ready to invest.
vAttach ___, place wax-up on a ___ ___
vAttach sprue, place wax-up on a crucible former
___ and ___ of pattern in ring is important.
You can still get a casting but its difficult to get a good, complete casting
You want about a ___ mm spru about ___ mm from top of ring and have
You want___ ___ wax pattern
You don’t want any sharp angles
Metal will flow into there and the it will flow into your pattern
Hit a flat wall it will just splatter everywhere instead of flowing smoothinly
Ring liner is placed for____
You have to have expansion bc investment is made out of gypsum and gypsum expands upon setting
You have to have room for correct expansion so that your casting will end up the right size
vOrientation and height of pattern in ring is important.
You can still get a casting but its difficult to get a good, complete casting
You want about a 6 mm spru about 6 mm from top of ring and have
You want room around wax pattern
You don’t want any sharp angles
Metal will flow into there and the it will flow into your pattern
Hit a flat wall it will just splatter everywhere instead of flowing smoothinly
Ring liner is placed for expansion
You have to have expansion bc investment is made out of gypsum and gypsum expands upon setting
You have to have room for correct expansion so that your casting will end up the right size
vCasting ring should have ring liner adapted to the inside of ring and ___ down with ___wax. After tacking, ___ liner lightly.
Wet the liner so that when you fill the ring up, it doesn’t suck water out of the investment.
If it sucks water out of the investment, that will change the Water to powder ratio of the investment. And that will change your expansion
Recall More is less and less is more
If you take water out your will get more expansion
If you have too much water you will get less expansion
vCasting ring should have ring liner adapted to the inside of ring and tacked down with sticky wax. After tacking, wet liner lightly.
Wet the liner so that when you fill the ring up, it doesn’t suck water out of the investment.
If it sucks water out of the investment, that will change the Water to powder ratio of the investment. And that will change your expansion
Recall More is less and less is more
If you take water out your will get more expansion
If you have too much water you will get less expansion
vSpray your wax-up with ___ to break the __ ___ of the wax
vDo not allow the surfactant to ___
vIf you get a little too much, light __ ___excess
ST is not good when you are trying to invest.
You will end up with little ___
Little bubbles of air in an investment will end up as little bubbles in the gold
Don’t let it pool up because you will get weird surface bc of bad setting of investment
vSpray your wax-up with surfactant to break the surface tension of the wax
vDo not allow the surfactant to pool
vIf you get a little too much, lightly blow off excess
ST is not good when you are trying to invest.
You will end up with little bubbles
Little bubbles of air in an investment will end up as little bubbles in the gold
Don’t let it pool up because you will get weird surface bc of bad setting of investment
Lost Wax Technique - Investing
vUse your ___ mixing bowl to mix the investment.
v____ investment by Whip-Mix Co.
vRead the instructions on the package and follow the directions.
vThe ring will not be on the __ __ at this point
In casting it is really important that you get correct expansions of materials. Need to follow all instructions
When you first go to invest, the ring will not be on top of the crucible former
Mix the investment by hand
Vacuum mix for about 40 seconds
Then use a brush and vibrate the investment into and over the crown
Put ring on crucible former and fill it up
Lost Wax Technique - Investing
vUse your vacuum mixing bowl to mix the investment.
vNovocast investment by Whip-Mix Co.
vRead the instructions on the package and follow the directions.
vThe ring will not be on the crucible former at this point
In casting it is really important that you get correct expansions of materials. Need to follow all instructions
When you first go to invest, the ring will not be on top of the crucible former
Mix the investment by hand
Vacuum mix for about 40 seconds
Then use a brush and vibrate the investment into and over the crown
Put ring on crucible former and fill it up
Lost Wax Technique - Investing
vMix the investment by ___ till completely ___ ( approx. __ seconds )
___ mix for ___ sec.
vUsing a ___, ___ investment into and onto wax pattern, place ring onto__ __r.
v___ the ring slowly, holding ring to ___ with ___ pressure
vMix the investment by hand till completely incorporated ( approx. 15 seconds )
vVacuum mix for 40 sec.
vUsing a brush, vibrate investment into and onto wax pattern, place ring onto crucible former.
vFill the ring slowly, holding ring to vibrator with indirect pressure
Lost Wax Technique - Burnout
vInvestment should____ ___according to the manufacturers’ directions, ___ min. in this case
vRemove the ___ ___
v
vInvestment should bench set according to the manufacturers’ directions, 40 min. in this case
vRemove the crucible former
v
Lost Wax Technique - Burnout
vPlace ___ in oven
vCheck __ __
vCheck___ end-point set
vPlace ring in oven
vCheck heat rate
vCheck temperature end-point set
Lost Wax Technique - Burnout
vBurnout is to ___oF
vIt takes approximately ___ hour to reach temperature
vOnce it reaches temperature you hold for___minutes (__ ___).
Then you cast
Hold it at that temp for 15 min
When it reaches 1200, that’s only the outside is 1200
Lost Wax Technique - Burnout
vBurnout is to 1200oF
vIt takes approximately 1 hour to reach temperature
vOnce it reaches temperature you hold for 15 minutes (heat soak).
Then you cast
Hold it at that temp for 15 min
When it reaches 1200, that’s only the outside is 1200
Lost Wax Technique - Casting
vCasting is the process by which the ___ from the pattern is converted to a replicate in ___ or ___
___ metal is accelerated into the ___ either by __ __ or __ ___ (___ or ___).
vGlass is “cast” using a ___ ___ to___ the molten glass into the mold.
Pressing of ceramics is casting of glass
But using pressurized ceramic rod to push the glass in rather than a casting machine to throw it in
Lost Wax Technique - Casting
vCasting is the process by which the mold from the pattern is converted to a replicate in alloy or glass.
vMolten metal is accelerated into the mold either by centrifugal force or air pressure (positive or negative).
vGlass is “cast” using a ceramic rod to press the molten glass into the mold.
Pressing of ceramics is casting of glass
But using pressurized ceramic rod to push the glass in rather than a casting machine to throw it in
Lost Wax Technique - Casting
vOur casting will be done with a ___ __ ___machine
Two pieces move independently of each other
Wind the casting machine, pull up the bar and lock it into place
Lost Wax Technique - Casting
vOur casting will be done with a broken arm casting machine
Two pieces move independently of each other
Wind the casting machine, pull up the bar and lock it into place
Lost Wax Technique - Casting
v___ the casting machine__ times _____
___ into place with __ ___
vPlace ___ and ___
vPull___ with crucible ___ from cradle
Its spring loaded
Place cradle and crucible
Put the gold in here
Pull platform with crucible away from cradle
And you start heating up the gold
Lost Wax Technique - Casting
vWind the casting machine 3 times clock-wise
vLock into place with locking bar
vPlace cradle and crucible
vPull platform with crucible away from cradle
Its spring loaded
Place cradle and crucible
Put the gold in here
Pull platform with crucible away from cradle
And you start heating up the gold
Lost Wax Technique - Casting
vWork in ___. This is a must!
vLight the___ and adjust the ___
v__ __ your crucible.
vOnce the crucible is pre-heated place the___ and begin the __ ___
vWork in pairs. This is a must!
vLight the torch and adjust the flame.
v Pre-heat your crucible.
vOnce the crucible is pre-heated place the gold and begin the melting process
Lost Wax Technique - Casting
vThe gold will __ and begin to __ __
vOnce melted it will look more like ____ than gold
vPlace the ring into the___
vPush the crucible platform ___ against the ring
Once the gold is heated and once it melts, it balls up
Lost Wax Technique - Casting
vThe gold will melt and begin to ball-up
vOnce melted it will look more like mercury than gold
vPlace the ring into the cradle
vPush the crucible platform up against the ring
Once the gold is heated and once it melts, it balls up
Lost Wax Technique - Casting
vNow you are ready to actually cast.
vYou will reach in and grasp the___ on the end of the casting machine and move them approx.__ ___ clockwise. The pin will ___
___ the weight. Get your hand and the torch out of the way. Use a smooth quick motion.
If it hits your hand it will break it
Lost Wax Technique - Casting
vNow you are ready to actually cast.
vYou will reach in and grasp the weights on the end of the casting machine and move them approx.1 inch clockwise. The pin will drop.
vRelease the weight. Get your hand and the torch out of the way. Use a smooth quick motion.
If it hits your hand it will break it
Lost Wax Technique - Casting
vTurn off torch.
vAllow the casting machine to ___ until adequate time has passed for the molten metal to ___ (20-30 sec.).
vThen, using the handle of the ___ stop the spinning.
Lost Wax Technique - Casting
vTurn off torch.
vAllow the casting machine to spin until adequate time has passed for the molten metal to solidify (20-30 sec.).
vThen, using the handle of the tongs stop the spinning.
Lost Wax Technique - Casting
vRemove the ring, carry with the tongs to the sink. Place on the edge of the ___ then ___
vQuenching is the plunging of the hot ring into___
What happens when you drop that hot ring into water?
You have __ ___
Lost Wax Technique - Casting
vRemove the ring, carry with the tongs to the sink. Place on the edge of the sink, then quench
vQuenching is the plunging of the hot ring into water.
What happens when you drop that hot ring into water?
You have mini explosion
Lost Wax Technique - Divesting
vThe casting is now ready to be ___ from the investment .
___ Crown
Clean it up. Cut off sprew and you fit it to your die
Lost Wax Technique - Divesting
vThe casting is now ready to be removed from the investment .
vCleaned Crown
Clean it up. Cut off sprew and you fit it to your die
Casting Investments
vGypsum-bonded
vHigh-temperature
vPhosphate-bonded
vEthyl Silicate
vSoldering
Casting Investments
vGypsum-bonded
vHigh-temperature
vPhosphate-bonded
vEthyl Silicate
vSoldering
Ideal Casting Investment -
Properties
v___ to manipulate
vSufficient ____
vResist ____
vSufficient___n
v___ - gas escape
vS___surface
v__ ___temperature range
vEasy to __ __
v___
v
v
v
vEasy to manipulate
vSufficient strength
vResist decomposition
vSufficient expansion
vPorous - gas escape
vSmooth surface
vNon-critical temperature range
vEasy to break away
vInexpensive
v
v
v
____ casting investment on the market today fits the 9 ideal properties!
No casting investment on the market today fits the 9 ideal properties!
Investment Components
vBinder - ___-temperature ___, ___
vRefractory - ___-temperature ___, ___
vModifiers - ___, ___ ___
vBinder - low-temperature strength, expansion
vRefractory - high-temperature strength, expansion
vModifiers - expansion, control tarnish
Investment Binders
__ ___ - ___-temperature alloys
___e - __-temperature alloys
___ - ___ -temperature alloys
Calcium Sulfateà Gypsum
Typical__ ___ would be invested in a gypsum investment
Phosphate: for nonprecious, high __ ___t, one that needs more heat to get the metal to melt.
When you cast metals into these investments…if you don’t have correct temperature for investment, flow wont be correct and you wont get cast that you need
Silica is not used very much anymore bc have to mix with __ __ and it puts off ___ and its flammable
Investment Binders
vCalcium sulfate - low-temperature alloys
vPhosphate - high-temperature alloys
vSilica - high-temperature alloys
Calcium Sulfateà Gypsum
Typical gold crown would be invested in a gypsum investment
Phosphate: fornonprecious, high Pd, Pt, one that needs more heat to get the metal to melt.
When you cast metals into these investments…if you don’t have correct temperature for investment, flow wont be correct and you wont get cast that you need
Silica is not used very much anymore bc have to mix with fresh ingredients and it puts off ethanol and its flammable
Investment Refractories
u____ - ___ expansion, at ___ temperatures
u___
u___ -__ expansion, at ____ temperatures
C: Gives you a lot of expansion at higher temperatures
Q: gives you less expansion at higher temperatures but if you look
T: gives you the most expansion at____ temperatures
These 3 types of refractories, think about where the expansion is coming from
T: Most of its expansion comes at lower T
C and Q: most of its expansion comes at higher T
Depending on the range of T for burnout determines how much of these materials you want to place in
Investment Refractories
uCristobalite - most expansion, at higher temperatures
uQuartz
uTridymite - least expansion, at higher temperatures
C: Gives you a lot of expansion at higher temperatures
Q: gives you less expansion at higher temperatures but if you look
T: gives you the most expansion at lower temperatures
These 3 types of refractories, think about where the expansion is coming from
T: Most of its expansion comes at lower T
C and Q: most of its expansion comes at higher T
Depending on the range of T for burnout determines how much of these materials you want to place in
Investment Modifiers
___ - controls ___
___- controls ___
___ ___ -___, ___
___ ___ - ___, __ ___
Phosphate investments overall are a more course investment and they have to put Monomagnesium phosphate in there so you can have smooth surface to work with. Without that, surface comes out like sand paper
Investment Modifiers
vNaCl - controls expansion
vGraphite - controls tarnish
vDisodium Phosphate - strength, expansion
vMonomagnesium phosphate - expansion, surface finish
Phosphate investments overall are a more course investment and they have to put Monomagnesium phosphate in there so you can have smooth surface to work with. Without that, surface comes out like sand paper
Gypsum-bonded Investment -
Composition
v60-75% ___ and/or ___
v25-35% ___ ___ ___
v2-3% ____
vNote: Increasing the ___/___ ratio ___ the hygroscopic expansion but ____the strength
If you raise this gypsum ratio (put in more gyp) you’ll get more expansion but it will get weaker bc quartz is responsible for a lot of its strength at higher T
Gypsum-bonded Investment -
Composition
v60-75% quartz and/or cristobalite
v25-35% calcium sulfate hemihydrate
v2-3% modifiers
vNote: Increasing the silica/stone ratio increases the hygroscopic expansion but decreases the strength
If you raise this gypsum ratio (put in more gyp) you’ll get more expansion but it will get weaker bc quartz is responsible for a lot of its strength at higher T
Gypsum-bonded Investment -
Use at _____ °C
v_____ decomposes above 700 °C
vBreaks down to produce __ ____ or ___
vGasses____ alloy
vDon’t use with___ and___ metal alloys
v(melting __ ___ high)
vMust use an ___ ___
It starts releasing gases that will embrittle the alloy
Gypsum investments are too weak to use without a ring.
Ring is used for strength and to control expansion
Without the ring, this stuff blows apart when you try to cast with it
Gypsum-bonded Investment -
Use at <700 °C
vCaSO4 decomposes above 700 °C
vBreaks down to produce sulphur dioxide or trioxide
vGasses embrittle alloy
vDon’t use with palladium and base metal alloys
v(melting temp. too high)
vMust use an investment ring
It starts releasing gases that will embrittle the alloy
Gypsum investments are too weak to use without a ring.
Ring is used for strength and to control expansion
Without the ring, this stuff blows apart when you try to cast with it
Gypsum-bonded Investment -
Silica Refractory
u___ change upon heating -
___ to ___transition
uExpansion– thermal _____ of SiO2 cause ____ to open from typical ___ to ___
When you heat gypsum bonded investments, you get a displasive change upon heating
Above___ C you get __ ___
You don’t want to get to fused silica
Gypsum-bonded Investment -
Silica Refractory
uDisplacive change upon heating -
alpha to beta transition
uExpansion– thermal inversion of SiO2 cause bonds to open from typical 140o to 180o
When you heat gypsum bonded investments, you get a displasive change upon heating
Above 1700 C you get fused silica
You don’t want to get to fused silica
op0-9iGypsum-bonded Investment -
Water
uReacts with ___ ___ ____
uAllows___
u____s on heating
u____e + ____–> ____
Gypsum-bonded Investment -
Water
uReacts with calcium sulfate hemihydrate
uAllows mixing
uEvaporates on heating
uCaSO4dihydrate + Heating “ CaSO4 anhydrate
Gypsum-bonded Investment -
Thermal Changes
vRoom Temp. –> 700 C - ___
v700 C –> Room Temp - ___ ___
vReheat - __ __, ___
What if you stick it I the oven and then realize I don’t have any gold
Don’t turn the oven off
So if you have it in the oven and don’t have any gold, don’t turn the oven off. Just try to find some gold
aQ45Gypsum-bonded Investment -
Thermal Changes
vRoom Temp. –> 700 C - expansion
v700 C –> Room Temp - unpredictable contraction
vReheat - unpredictable expansion, cracking
What if you stick it I the oven and then realize I don’t have any gold
Don’t turn the oven off
So if you have it in the oven and don’t have any gold, don’t turn the oven off. Just try to find some gold
Gypsum-bonded Investment -
Dimensional Changes
v___
v___
v___
The reason why you want all of this expansion in your investment is that when you cast hot metal into the investment, Metal will ___ when it ___
You need a little expansion to accommodate for that or your casting wont fit
Gypsum-bonded Investment -
Dimensional Changes
vSetting
vHygroscopic
vThermal
The reason why you want all of this expansion in your investment is that when you cast hot metal into the investment, Metal will shrink when it cools.
You need a little expansion to accommodate for that or your casting wont fit
Gypsum-bonded Investment -
Role of Water
v___ ___ ___ affects setting expansion
vExposure to water after mixing - allows ____ growth of crystals (hygroscopic expansion)
’
More is less and less is more
Too much waterà it will be smaller
Hygroscopic investments
Set in a water bath
He could never get them to fit right
Gypsum-bonded Investment -
Role of Water
vWater-powder ratio affects setting expansion
vExposure to water after mixing - allows greater growth of crystals (hygroscopic expansion)
More is less and less is more
Too much waterà it will be smaller
Hygroscopic investments
Set in a water bath
He could never get them to fit right
Manipulation of Gypsum Investments
vIn gypsum investments always remember that ___ ___ ___ and ___ ___ __e where W/P ratio is involved.
Manipulation of Gypsum Investments
vIn gypsum investments always remember that more is less and less is more where W/P ratio is involved.
High-Temperature
Casting Investments
vSpecial investments required for casting __ __ __ and ___ __ __ ___ alloys
v___ and ___metal alloys cast at higher temperatures, as do High ___ /High ___ alloys.
This is bc The metals melt at a very high Temp
PFM alloys have to melt at higher temp that gold bc you are bonding porcelain to it and you make porcelain at very high T
High-Temperature
Casting Investments
vSpecial investments required for casting removable partial denture and porcelain-fused-to-metal alloys
vPalladium and base metal alloys cast at higher temperatures, as do High Gold /High Platinum alloys.
This is bc The metals melt at a very high Temp
PFM alloys have to melt at higher temp that gold bc you are bonding porcelain to it and you make porcelain at very high T
Mold Temperature ___700 C -
Requirements
___ investment
___ ___ investment
vMore ____n (expansion) for ___ of alloys on cooling from higher temperatures
Melting at a higher temperature so it shrinks ___
Need more expansion to commpensate for it
Mold Temperature >700 C -
Requirements
vStronger investment
vLess reactive investment
vMore compensation (expansion) for shrinkage of alloys on cooling from higher temperatures
Melting at a higher temperature so it shrinks more
Need more expansion to commpensate for it
High-Temperature
Casting Investments
__ bonded - __ __
___-bonded
High-Temperature
Casting Investments
vPhosphate-bonded - most common
vSilica-bonded
Functional Components
vRefractory
vBinder (<20%)
vModifying chemicals
Binders: ___, ______ ___
Fillers/Refractoy:___/___
Other ingredients are used as buffereing agents: C
Functional Components
vRefractory
vBinder (<20%)
vModifying chemicals
Binders: MgO, Mono-ammonium phosphate
Fillers/Refractoy: Quartz/Cristobolite
Other ingredients are used as buffereing agents: C
Types of Expansion
___ expansion
___ expansion
vThermal expansion
vSetting expansion
Phosphate-bonded Investment
vAmmonium diacid phosphate -___ temperature ___
vMagnesium oxide - __ temperature ___
vAmmonium diacid phosphate - room temperature strength
vMagnesium oxide - room temperature strength
Phosphate-bonded Investment
vSilica - refractory
vSilica reacts with ___P at high temperatures for ___ strength
vDifferent particlep sizes affect ___
vCan be used ___ OR ___ a casting ring
Ammonium Diphosphate
Phosphate investments are usually a larger particle size, that’s why they add the modifers in to smooth the surface
Normally recommend no casting ring
Pour in plastic ring and pop it out before you put in oven
Reason is so that it can expand more
You want more expansion bc metal shrinks more
Phosphate-bonded Investment
vSilica - refractory
vSilica reacts with ADP at high temperatures for increased strength
vDifferent particle sizes affect expansion
vCan be used with or without a casting ring
Ammonium Diphosphate
Phosphate investments are usually a larger particle size, that’s why they add the modifers in to smooth the surface
Normally recommend no casting ring
Pour in plastic ring and pop it out before you put in oven
Reason is so that it can expand more
You want more expansion bc metal shrinks more
Phosphate-Bonded Investment -
Special Liquid
v___ ___ in water
___ strength
vIncreased __ ___n due to ___ expansion
Don’t just use plain water to mix the phosphate investments
Special liqu: Silica sol in water
Ratio of special liquid to water affects the expansion
If casting with gold, use less % of special water
Not easy to work with for gold
Phosphate-Bonded Investment -
Special Liquid
vSilica sol in water
vIncreased strength
vIncreased setting expansion due to hygroscopic expansion
Don’t just use plain water to mix the phosphate investments
Special liqu: Silica sol in water
Ratio of special liquid to water affects the expansion
If casting with gold, use less % of special water
Not easy to work with for gold
Investment for All-Ceramics
vTwo types developed
v __ __/___ ___ Investment
v___ ___ Investment
Refractory Die material, the ___ is built ___ Onto the die and fired
Pressable: Wax up, invest, burn down, glass pressed into the mold
Investment for All-Ceramics
vTwo types developed
v Cast Glass/Pressable Ceramic Investment
v Refractory Die Investment
Refractory Die material, the porcelain is built directly onto the die and fired
Pressable: Wax up, invest, burn down, glass pressed into the mold
Investment for All-Ceramics
vCast Glass/ Pressable Ceramic Investment
___-bonded investment
vMust be ___ to withstand the pressures directed on it from the __ ___in the pressable ceramic ___
Set up to where they have a ___ ___
Put ring in oven, burn it out
When it reaches a certain T, take it out, flip it up and it has a specific shape where it was on the screw former and you put a ceramic rod in there, set it oven.
When glass gets molten, hydraulics kick in and it presses that glass into the mold
Investment for All-Ceramics
vCast Glass/ Pressable Ceramic Investment
vPhosphate-bonded investment
vMust be strong to withstand the pressures directed on it from the ceramic rod in the pressable ceramic furnaces.
Set up to where they have a hydraulic press
Put ring in oven, burn it out
When it reaches a certain T, take it out, flip it up and it has a specific shape where it was on the screw former and you put a ceramic rod in there, set it oven.
When glass gets molten, hydraulics kick in and it presses that glass into the mold
Investment for All-Ceramics
vRefractory Die Investment
v____-Bonded Investment with __ __ ___for ___ reproduction
vMaterial is poured into an impression of preparations similar to__ __ materials.
vThe all-ceramic restoration is constructed ____ on the refractory die.
vNote: Coefficient of Thermal Expansion of ___ AND ___ must be matched.
Use this just like you would take an impression
Lets say we wanted to make some veneers
Take impression of veneers and then pour it up with this refractory investment and then restoration is constructed directly on that refractory die
Negative: They are pretty specific for the porcelains that you use on them
Investment for All-Ceramics
vRefractory Die Investment
vPhosphate-Bonded Investment with fine grain filler for detail reproduction
vMaterial is poured into an impression of preparations similar to gypsum die materials.
vThe all-ceramic restoration is constructed directly on the refractory die.
vNote: Coefficient of Thermal Expansion of investment and porcelains must be matched.
Use this just like you would take an impression
Lets say we wanted to make some veneers
Take impression of veneers and then pour it up with this refractory investment and then restoration is constructed directly on that refractory die
Negative: They are pretty specific for the porcelains that you use on them
vRefractory Die Investment
Trim it up
Take a spacer and paint on the stone
Put it in oven
Let it set
Has high ammonium content
Let it cool
Mark margins with special ceramic pencil
Build porcelain on it, fire it
Trim it up
Take a spacer and paint on the stone
Put it in oven
Let it set
Has high ammonium content
Let it cool
Mark margins with special ceramic pencil
Build porcelain on it, fire it
Titanium Investments
v___-based, ___-based___ bonded investments
vSiO2, ZrSiO4, NH4H2PO4
vTicoat
vShera
____, ____ based investments
vMgO, Allumina, CaO
vTitavest CB
vGiulini
vRematitan Ultra
vSelevest D
Use these for Titanium
Titanium doesn’t act like any other metal
If use the wrong investment, Titanium can pull the investment into the surface of the metal
vSilica-based, Zircon-based phosphate bonded investments
vSiO2, ZrSiO4, NH4H2PO4
vTicoat
vShera
v MgO, MgAl based investments
vMgO, Allumina, CaO
vTitavest CB
vGiulini
vRematitan Ultra
vSelevest D
Use these for Titanium
Titanium doesn’t act like any other metal
If use the wrong investment, Titanium can pull the investment into the surface of the metal
Silica-bonded Investment
vSilica-bonded, ingredients - ethyl silicate/HCl, colloidal silica in water, sodium silicate
vSilica – ____
vUsed for___ melting base metal alloys in the construction of ___ ___ frameworks
vSilica-bonded, ingredients - ethyl silicate/HCl, colloidal silica in water, sodium silicate
vSilica – refractory
vUsed for high melting base metal alloys in the construction of partial denture frameworks
Silica-bonded Investment
vTechnique - ___ ingredients must be mixed before use
vDisadvantages of ethyl silicate - ____ components released during processing,___
Ethanol is released
Instead of silica, they have many good phosphate investments
Pretty much all labs have gone away from silica for partials
Silica-bonded Investment
vTechnique - fresh ingredients must be mixed before use
vDisadvantages of ethyl silicate - flammable components released during processing, expensive
Ethanol is released
Instead of silica, they have many good phosphate investments
Pretty much all labs have gone away from silica for partials
Soldering Investment - Purpose
v__ __s,___ ___
vSolder ___, ___. ___ __ __
Lets say you have a partial denture
And you have a clasp
Patient comes in bc clasp is broken off of the partial
How are you going to put another clasp on there?
You can solder one on
In the old days you had to solder together your gold bridges
Soldering Investment - Purpose
vHold parts, protect metal
vSolder crowns, bridges, partial denture clasps
Lets say you have a partial denture
And you have a clasp
Patient comes in bc clasp is broken off of the partial
How are you going to put another clasp on there?
You can solder one on
In the old days you had to solder together your gold bridges
Soldering Investment - Composition
uType I ___-bonded dental brazing (soldering) investments
uType II : ))))-bonded dental brazing (soldering) investments
What we actually do in dentistry is ____…not really soldering
Type I: use with lower T melting metals
Type II: use for higher T melting metals
Soldering Investment - Composition
uType I : Gypsum-bonded dental brazing (soldering) investments
uType II : Phosphate-bonded dental brazing (soldering) investments
What we actually do in dentistry is brazing…not really soldering
Type I: use with lower T melting metals
Type II: use for higher T melting metals
Soldering Investment -
Properties
uANSI/ADA Specification No. 93
Quality – uniform and free from foreign matter and lumps
Fluidity
Setting Time – shall not vary by more than ___% of time claimed by manufacturer
vCompressive Strength – _____ MPa
vLinear setting expansion – shall not vary by more than __% of manufacturers claim
vLinear thermal expansion – shall not vary by more than___ % of manufacturers claim
Soldering Investment -
Properties
uANSI/ADA Specification No. 93
Quality – uniform and free from foreign matter and lumps
Fluidity
Setting Time – shall not vary by more than 30% of time claimed by manufacturer
vCompressive Strength – 2.0 – 10.0 MPa
vLinear setting expansion – shall not vary by more than 15% of manufacturers claim
vLinear thermal expansion – shall not vary by more than 15% of manufacturers claim
Soldering Investment -
Properties
vDesigned to have ___ setting and thermal expansion
vType I for ___r melting point alloys
vType II for____ melting point alloys
vParticle size normally ___ since smoothness of the mass is____
Soldering Investment -
Properties
vDesigned to have low setting and thermal expansion
vType I for lower melting point alloys
vType II for high melting point alloys
vParticle size normally larger since smoothness of the mass is immaterial
Investments contain
free silica
