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Biomaterials > Gypsum > Flashcards

Gypsum Flashcards

1
Q

Gypsum Materials

Mineral - gypsum (__________)

___ ____ ____ ____

____ or ____

Mostly ___ but they do make some synthetic

Foundation of all the dental stones you will use

A

Gypsum Materials

Mineral - gypsum (CaSO4 2H2O)

calcium sulfate di-hydrate

Mined or synthetic

Mostly mined but they do make some synthetic

Foundation of all the dental stones you will use

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2
Q

____ of gypsum into ___ is accomplished by____ ____ gypsum to _______ degrees C.

How they take it from mined rocks and make it to a usable plaster

This is just heating crushed gypsum

To get the diff types of dental stones depends on what you do when you calcinate the gypsum

A

Calcination of gypsum into plaster is accomplished by heating crushed gypsum to 110-120 degrees C.

How they take it from mined rocks and make it to a usable plaster

This is just h eating crushed gypsum

To get the diff types of dental stones depends on what you do when you calcinate the gypsum

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3
Q

__________ + _____ <–> ______ + _____

( Gypsum ) ( Dental Plaster –

calcium sulfate___ ____)

Calcination ____ will determine type of plaster formed.

If you just __ ___ you get Plaster of Parisà Ortho, not very strong

If you ___ ___ with ____ you get Model Stoneà Diagnostic Cast

If you___ ___ with____ you get Die Stone

A

CaSO4 . 2H2O + Heat D CaSO4.1/2H2O + 11/2H2O

( Gypsum ) ( Dental Plaster –

calcium sulfate hemi-hydrate)

Calcination environment will determine type of plaster formed.

If you just heat it you get Plaster of Parisà Ortho, not very strong

If you close Kettle with Steam you get Model Stoneà Diagnostic Cast

If you close Kettle with CaCl2 you get Die Stone

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4
Q

Types of Gypsum

Type 1 -

Type 2 -

Type 3 -

Type 4 -

Type 5 -

A

Types of Gypsum

Type 1 - Impression plaster

Type 2 - Model plaster

Type 3 - Dental stone

Type 4 - High-strength dental stone (low expansion)

Type 5 - High-strength dental stone (high expansion)

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5
Q

Chemical Formula

_________ - The chemical formula is the same for all 5 types of ___ ___

Calcium sulfate hemi-hydrate

A

Chemical Formula

CaSO4 1/2H2O - The chemical formula is the same for all 5 types of dental stone.

Calcium sulfate hemi-hydrate

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6
Q

Chemical Reaction

Plaster/ Die stone Set Gypsum

CASO4 1/2H2O + water à CaSO4 2H2O +heat

This reaction accompanied by:

1) evolution of heat- exothermic reaction
2) development of strength
3) setting expansion

The way the stone sets is thru a crystalline growth procedure so you get expansion

A

Chemical Reaction

Plaster/ Die stone Set Gypsum

CASO4 1/2H2O + water à CaSO4 2H2O +heat

This reaction accompanied by:

1) evolution of heat- exothermic reaction
2) development of strength
3) setting expansion

The way the stone sets is thru a crystalline growth procedure so you get expansion

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7
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A
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9
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10
Q
A
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11
Q

Excess Water

Excess Water, mL/100 g

Model plaster ____

Dental stone 9-13

HSDS ____

This is water trapped in the ___ ___ ___

The one that packs together nicely has less water

A

Excess Water

Excess Water, mL/100 g

Model plaster 18-31

Dental stone 9-13

HSDS 0-5

This is water trapped in the inter-crystalline spaces.

The one that packs together nicely has less water

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12
Q

Properties

ANSI/ADA Spec. 25 - certified products

Quality – ____ and free of ___ ___ and ___

____ at pouring (type ___ only)

Setting Time – type I ____ min., all other types of stone within ___% of manufacturer’s claim

Linear setting Expansion –

I : 0-___%

II : 0-___%

III : 0-___%

IV : 0-___%

V : ___-0.__%

Fracture (type ___ only) – Must break ___ and be able to be___

Compressive strength-

I : 4.0 MPa min. 8.0MPa max.

II : 9.0 MPa min.

III : 20.0 MPa min.

IV : 35.0 MPa min.

V : 35.0 MPa min.

Reproduction of ___

Most people don’t use Type I (for impressions) anymoreà Now we use other impression materials

A

Properties

ANSI/ADA Spec. 25 - certified products

Quality – uniform and free of foreign matter and lumps

Fluidity at pouring (type I only)

Setting Time – type I 2.5-5.0 min., all other types of stone within 20% of manufacturer’s claim

Linear setting Expansion –

I : 0-.15%

II : 0-.30%

III : 0-.20%

IV : 0-.15%

V : 0.16-0.30%

Fracture (type I only) – Must break cleanly and be able to be reassembled

Compressive strength-

I : 4.0 MPa min. 8.0MPa max.

II : 9.0 MPa min.

III : 20.0 MPa min.

IV : 35.0 MPa min.

V : 35.0 MPa min.

Reproduction of detail

Most people don’t use Type I (for impressions) anymoreà Now we use other impression materials

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13
Q

Properties

Compressive strength -____ > ___ >___

Tensile strength - very ___ on all of them

Abrasion resistance - __> __>___

Setting time – __ to ___ min

That is the initial set

That is not the time you need to leave it in the impression before you pull it out

Don’t rush separation

Setting expansion ___ ____ ___ ____ _____

Important for precision fits

A

Properties

Compressive strength - HSDS>DS>MP

Tensile strength - very low on all of them

Abrasion resistance - HSDS>DS>MP

Setting time – 8 to 16 min

That is the initial set

That is not the time you need to leave it in the impression before you pull it out

Don’t rush separation

Setting expansion IP=HSDS<ds></ds>

<p>Important for precision fits</p>

<p> </p>

</ds>

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14
Q

Manipulation Affects Set

Spatulation time

An____ in mix time, gives a ____ in set time

If you hand mix as you spatulate longer the set time goes down

When you mechanically and vacuum spatulate the time goes down much ____

A

Manipulation Affects Set

Spatulation time

An increase in mix time, gives a decrease in set time

If you hand mix as you spatulate longer the set time goes down

When you mechanically and vacuum spatulate the time goes down much quicker

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15
Q

Manipulation Affects Set

Water temperature

As temperature increases, set time____, to a point, then begins to ____ again

Warmer waterà Faster Set

However if it gets too hot (past _____) it goes backwards (setting time will increase)

100F is not that hot (just warm)

If you are going to use hotter water, use warm water not hot hot water

At ____ , _____ of ___and ____ are ____, therefo ___ ___

Boiling Water

A

Manipulation Affects Set

Water temperature

As temperature increases, set time decreases, to a point, then begins to increase again

Warmer waterà Faster Set

However if it gets too hot (past 100F) it goes backwards (setting time will increase)

100F is not that hot (just warm)

If you are going to use hotter water, use warm water not hot hot water

At 100oC solubility of dihydrate and hemihydrate are equal, therefor No Set

Boiling Water

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16
Q

Manipulation Affects Set

Humidity during storage

Early- ____, Late- ____

Open stone storage container

Gypsum is very sus to absorbing moisture from the atm

As it absorbs water early on you get a decrease in your set time

As it gets more water and starts to reach the point of saturation, the set time increases and eventually it will get to the point where it will not __ at ___

____ systems – ___, ___, ___

All act as ____ of Set

Poison the ___ ___ ___

If you take an impression and patient bled into it, this will keep your stone from setting

Hydrocolloid systems means alginates

Need to wait to separate it

A

Manipulation Affects Set

Humidity during storage

Early- Decreases, Late- Increases

Open stone storage container

Gypsum is very sus to absorbing moisture from the atm

As it absorbs water early on you get a decrease in your set time

As it gets more water and starts to reach the point of saturation, the set time increases and eventually it will get to the point where it will not set at all.

Colloidal systems – hydrocolloid, saliva, blood

All act as retarders of Set

Poison the crystalline matrix nuclei

If you take an impression and patient bled into it, this will keep your stone from setting

Hydrocolloid systems means alginates

Need to wait to separate it

17
Q

Manipulation: Water: Powder Ratio

W/P ratio – affects the ___, ___, ___

Use slurry water instead of distilled water:

Use Gypsum Hardener instead of Distilled Water:

Increase the Mixing Time:

Mixing under Vacuum:

Use extra water: Increase

A

Manipulation: Water: Powder Ratio

W/P ratio – affects the consistency, expansion, strength

Use slurry water instead of distilled water: Shorter Set Time, Lower compressive Strength, Higher Setting Expansion

Use Gypsum Hardener instead of Distilled Water: Higher Compressive Strength, Higher Setting Expansion, Higher Fluidity

Increase the Mixing Time: Shorter Set Time, Higher Compressive Strength, Increase Expansion, Lower Fluidity

Mixing under Vacuum: Higher Strength, Higher Fluidity

Use extra water: Increase Set Time, Lower Compressive Strength, Lower Expansion, Higher Fluidity

18
Q

Manipulation

Surfactants & vibration - ___ ____

Surfactant=Debubblizer

Spray it on impression

Reduces ___ ___ and lets you get a better ___

If you use too much of it and allow it to pool up, you will get a billion ____s in your stone.

Spray lightly and then use __ ___ to blow the excess out

Immersion in ___ during set - ___ in expansion (___ expansion)

Hydroscopic: you poured it up and then immediately put it into a water bath

Hardening solutions – typically a ___% ___ solution

Increase the surface hardness but ___ ___ is not necessarily improved

Usually causes ___ expansion

A

Manipulation

Surfactants & vibration - reduce bubbles

Surfactant=Debubblize

Spray it on impression

Reduces Surface Tension and lets you get a better pour

If you use too much of it and allow it to pool up, you will get a billion microbubbles in your stone.

Spray lightly and then use air syringe to blow the excess out

Immersion in water during set - increase in expansion (hygroscopic expansion)

Hydroscopic: you poured it up and then immediately put it into a water bath

Hardening solutions – typically a 30% silica solution

Increase the surface hardness but abrasion resistance is not necessarily improved

Usually causes increased expansion

19
Q

Chemical Modifiers

Accelerators - Decrease the set time

___ - Most common, ___ concentration

___- ___ concentration

Retarders – Increase the set time

___ – __ concentration

___, ___ ___

Found in alginate

___- > ___ concentration

Most also affect strength and expansion

A

Chemical Modifiers

Accelerators - Decrease the set time

K2SO4 - Most common, any concentration

NaCl - < 5% concentration

Retarders – Increase the set time

Borax – Any concentration

Agar, gum Arabic

Found in alginate

NaCl - > 20% concentration

Most also affect strength and expansion

20
Q

Setting-expansion inhibitors (Decrease Expansion)

___

___

____

A

Setting-expansion inhibitors (Decrease Expansion)

K2SO4

KCL

potassium tartrate

21
Q

Power-Driven Vacuum Mixing

Less ____

Increased ____

A

Power-Driven Vacuum Mixing

Less bubbles

Increased strength

22
Q

Packaging

Bulk – ___ ___ or ____

Have to keep this covered properly!

Cheaper

Pre-packaged ____

$$$$$$

Pre-packaged __ and ___ system

A

Packaging

Bulk – Bags, boxes or buckets

Have to keep this covered properly!

Cheaper

Pre-packaged envelopes

$$$$$$

Pre-packaged mix and toss system

23
Q

Die Materials

___

Type __

Type __

____

What you use to wax on to create a dental restoration (Patient takes their tooth home with them so you need a replica of it)

A

Die Materials

Gypsum

Type IV

Type V

Epoxy

What you use to wax on to create a dental restoration (Patient takes their tooth home with them so you need a replica of it)

24
Q

fg,32Die Materials-Gypsum Type IV

All type IV die materials are high ___/low ___

There are three types of Type IV material: ___ gypsum, __ ___ gypsum and ___

Setting expansion _____% ADA specification 25 section 5.4

A

Die Materials-Gypsum Type IV

All type IV die materials are high strength/low expansion.

There are three types of Type IV material: regular gypsum, resin fortified gypsum and scannable.

Setting expansion 0% - 0.15% ADA specification 25 section 5.4

25
Q

Resin Fortified Gypsum

Type of resin used is a well guarded secret.

Most widely used is a ___ ___ ___

Reasons for addition:

Increase ___

Decrease___

He doesn’t notice much difference bw this and regular, but its way more $$$$

New Type IV – Scannable die stone

Used with the opti-electronic/laser scanning systems.

Reflective ingredient added to increase ___ and reduce ___

To get a good scan of the stone

A lot of people are scanning impression instead of stone so this hasn’t taken off like it could have

A

Resin Fortified GypsumType of resin used is a well guarded secret.

Most widely used is a Poly Vinyl Acetate.

Reasons for addition:

Increase Strength

Decrease Brittleness

He doesn’t notice much difference bw this and regular, but its way more $$$$

New Type IV – Scannable die stone

Used with the opti-electronic/laser scanning systems.

Reflective ingredient added to increase reflection and reduce refraction.

To get a good scan of the stone

A lot of people are scanning impression instead of stone so this hasn’t taken off like it could have

26
Q

Type V

___h Strength ___h Expansion Gypsum

Setting expansion ____ ADA specification 25 section 5.4

A

Type V

High Strength High Expansion Gypsum

Setting expansion 0.16% - 0.30% ADA specification 25 section 5.4

27
Q

Die Materials – Epoxy

Polymer resin – Bis Phenol with silicahttps://www.brainscape.com/decks/4459065/cards/167308433/edit#

___ agent needed before ___

___ Fluidity

Material ____ on set -____%

It wouldn’t fit on tooth

Polyurethane Blocks

Used with the ___ impression scanners. Digital impression is sent to factory and model is milled from a solid block. No ___ ro ____n whatsoever.

Epoxy Resin

Models are created with the aid of _____

i.e.: __ ___

No exp or shrinkage

A

Die Materials – Epoxy

Polymer resin – Bis Phenol with silica

Release agent needed before pouring

High Fluidity

Material shrinks on set - .1% to .3%

It wouldn’t fit on tooth

Polyurethane Blocks

Used with the digital impression scanners. Digital impression is sent to factory and model is milled from a solid block. No shrinkage or expansion whatsoever.

Epoxy Resin

Models are created with the aid of Stereolithograpy,

i.e.: 3D printing.

No exp or shrinkage

28
Q

Ease of Use

Gypsum ___

Epoxy ___ or ___

depends on which type

A

Ease of Use

Gypsum Easy

Epoxy M. difficult or easiest,

depends on which type

29
Q

Time Required

Gypsum ___

Epoxy ___ ___ or ___

A

Time Required

Gypsum Short

Epoxy Several hours, or days

30
Q

Equipment Required

Gypsum ___

Epoxy ___ to ___

Gypsum – ___ ,___ ___, ___, ___ ___

Epoxy - for the milled models, you need a ___ ___, ___ , ___ ___ ; for regular epoxy, you need a ___, _____ ____ , ____, and ___material.

A

Equipment Required

Gypsum Minimal

Epoxy Minimal to extensive

Gypsum – vibrator, mixing bowl, spatula, vacuum mixer.

Epoxy - for the milled models, you need a digital scanner, computer and internet connection; for regular epoxy, you need a vibrator, mixing bowl, spatula, and boxing material.

31
Q

Harmful Chemicals

Gypsum ___

Epoxy ___ or ___

____ resins in ____r epoxy can in some cases cause ___ or ___irritation.

A

Harmful Chemicals

Gypsum None

Epoxy Some or none

Uncured resins in regular epoxy can in some cases cause respiratory or skin irritation.

32
Q

Compatibility with Impressions

Gypsum ___

Epoxy ___ to ___

A

Compatibility with Impressions

Gypsum Excellent

Epoxy Limited to N/A

33
Q

Dimensional Change

Gypsum Slight ____

Epoxy Slight ___ (___) or ___

A

Dimensional Change

Gypsum Slight expansion

Epoxy Slight contraction (PR)

or None

34
Q

Accuracy

Gypsum

Epoxy

A

Accuracy

Gypsum Good

Epoxy Good

35
Q

Abrasion Resistance

Gypsum ___

Epoxy ____

A

Abrasion Resistance

Gypsum Poor

Epoxy Good

Biomaterials (15 decks)

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