Casting and Soldering Investments

Question 1

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.

Answer 1

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.

Question 2

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.

Answer 2

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.

Question 3

–

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.

Answer 3

–

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.

Question 4

v___ your pattern

v___ your pattern

v___ t the pattern

v__ __(___)

v__

v__ and __ your casting

Answer 4

vMake your pattern

vSprue your pattern

vInvest the pattern

vWax elimination (Burnout)

vCast

vFinish and polish your casting

Question 5

vPattern is ____ -=and made ready to invest.

Answer 5

vPattern is created and made ready to invest.

Question 6

vAttach ___, place wax-up on a ___ ___

Answer 6

vAttach sprue, place wax-up on a crucible former

Question 7

___ 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

Answer 7

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

Question 8

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

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

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

Answer 11

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

Question 12

Lost Wax Technique - Burnout

vInvestment should____ ___according to the manufacturers’ directions, ___ min. in this case

vRemove the ___ ___

v

Answer 12

vInvestment should bench set according to the manufacturers’ directions, 40 min. in this case

vRemove the crucible former

v

Question 13

Lost Wax Technique - Burnout

vPlace ___ in oven

vCheck __ __

vCheck___ end-point set

Answer 13

vPlace ring in oven

vCheck heat rate

vCheck temperature end-point set

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

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 __ ___

Answer 18

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

Question 19

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

Answer 19

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

Question 20

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

Answer 20

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

Question 21

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.

Answer 21

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.

Question 22

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 __ ___

Answer 22

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

Question 23

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

Answer 23

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

Question 24

Casting Investments

vGypsum-bonded

vHigh-temperature

vPhosphate-bonded

vEthyl Silicate

vSoldering

Answer 24

Casting Investments

vGypsum-bonded

vHigh-temperature

vPhosphate-bonded

vEthyl Silicate

vSoldering

Question 25

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

Answer 25

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

Question 26

____ casting investment on the market today fits the 9 ideal properties!

Answer 26

No casting investment on the market today fits the 9 ideal properties!

Question 27

Investment Components

vBinder - ___-temperature ___, ___

vRefractory - ___-temperature ___, ___

vModifiers - ___, ___ ___

Answer 27

vBinder - low-temperature strength, expansion

vRefractory - high-temperature strength, expansion

vModifiers - expansion, control tarnish

Question 28

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

Answer 28

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

Question 29

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

Answer 29

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

Question 30

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

Answer 30

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

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

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

Answer 33

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

Question 34

op0-9iGypsum-bonded Investment -
Water

uReacts with ___ ___ ____

uAllows___

u____s on heating

u____e + ____–> ____

Answer 34

Gypsum-bonded Investment -
Water

uReacts with calcium sulfate hemihydrate

uAllows mixing

uEvaporates on heating

uCaSO4dihydrate + Heating “ CaSO4 anhydrate

Question 35

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

Answer 35

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

Question 36

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

Answer 36

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

Question 37

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

Answer 37

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

Question 38

Manipulation of Gypsum Investments

vIn gypsum investments always remember that ___ ___ ___ and ___ ___ __e where W/P ratio is involved.

Answer 38

Manipulation of Gypsum Investments

vIn gypsum investments always remember that more is less and less is more where W/P ratio is involved.

Question 39

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

Answer 39

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

Question 40

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

Answer 40

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

Question 41

High-Temperature
Casting Investments

__ bonded - __ __

___-bonded

Answer 41

High-Temperature
Casting Investments

vPhosphate-bonded - most common

vSilica-bonded

Question 42

Functional Components

vRefractory

vBinder (<20%)

vModifying chemicals

Binders: ___, ______ ___

Fillers/Refractoy:___/___

Other ingredients are used as buffereing agents: C

Answer 42

Functional Components

vRefractory

vBinder (<20%)

vModifying chemicals

Binders: MgO, Mono-ammonium phosphate

Fillers/Refractoy: Quartz/Cristobolite

Other ingredients are used as buffereing agents: C

Question 43

Types of Expansion

___ expansion

___ expansion

Answer 43

vThermal expansion

vSetting expansion

Question 44

Phosphate-bonded Investment

vAmmonium diacid phosphate -___ temperature ___

vMagnesium oxide - __ temperature ___

Answer 44

vAmmonium diacid phosphate - room temperature strength

vMagnesium oxide - room temperature strength

Question 45

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

Answer 45

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

Question 46

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

Answer 46

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

Question 47

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

Answer 47

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

Question 48

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

Answer 48

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

Question 49

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

Answer 49

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

Question 50

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

Answer 50

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

Question 51

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

Answer 51

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

Question 52

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

Answer 52

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

Question 53

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

Answer 53

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

Question 54

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

Answer 54

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

Question 55

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

Answer 55

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

Question 56

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

Answer 56

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

Question 57

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____

Answer 57

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

Question 58

Investments contain

Answer 58

free silica