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Fixed Prosth, Module I > Impression Materials and Custom Tray Fabrication > Flashcards

Impression Materials and Custom Tray Fabrication Flashcards

1
Q

Desirable Qualities

lPleasant ____, taste, acceptable color
lAbsence of ____ or irritant constituents
lAdequate ____ for storage and distribution
l____ commensurate with results obtained
lEasy to use with ____ equipment
lSetting characteristics that meet clinical requirements
lSatisfactory ____ and texture
lReadily ____ oral tissues
lElastic properties with freedom from ____ after strain
l Adequate strength so it will not break or tear on removal
l Dimensional ____ over temperature and humidity ranges
l ____ with cast and die materials
l ____in clinical use
l Readily ____ without loss of accuracy

A 
strength
toxic
shelf life
minimum
consistency
wets
permanent deformation
stability
compatibility
accuracy
disinfected
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2
Q

Types of Impression Material

Nonelastic

  • ____
  • ____
  • ____
Elastic
Hydrocolloids:
- \_\_\_\_
- \_\_\_\_
Nonaqueous elastomers:
- \_\_\_\_
- \_\_\_\_
--- condensation
--- addition (vinyl)
- \_\_\_\_
A

impression compound
plaster
zinc oxide-eugenol

alginate
agar
polysulfides
silicones
polyethers
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3
Q

(1)Alginate (irreversible)
Hydrocolloid
l Most widely ____ impression material in dentistry
l Uses
– ____ impressions
l____ models
l____ models
– Removable partial dentures
lPartial removable dental prostheses
– Preliminary complete denture impressions
l Not ____ enough for partial fixed dental prosthesis impressions!

A 
used
preliminary
study
orthodontic
accurate
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4
Q 
Composition
Alginate (irreversible) Hydrocolloid
l\_\_\_\_ and calcium sulfate dihydrate
– reactants
l\_\_\_\_
– Retarder
– Adjusted by the manufacturer to produce regular or fast \_\_\_\_
A

sodium or potassium alginate
reactants
set

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5
Q 
Composition
Alginate (irreversible) Hydrocolloid
lReinforcing filler
– Controls \_\_\_\_ of the set gel
l\_\_\_\_ or alkali zinc fluorides
– Provides good surfaces on \_\_\_\_ 
l\_\_\_\_ and flavoring agents
A

stiffness
potassium sulfate
gypsum
coloring

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6
Q

Composition
Alginate (irreversible) Hydrocolloid
l Materials change from a ___ phase to the ___ phase due to a chemical reaction when product reacts with ___
– 2Na3PO4 +3CaSO4 –> 3Ca (PO4)2 +3Na2SO4
– Na alginate + CaSO4 (____) – H2O –> (____) Ca alginate +Na2SO4

A

sol

gel

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7
Q

Composition

alginate (irreversible) hydrocolloid

Sol: solid phase dispersed in ____ phase. Usually has ____ properties

Gel: Solid and liquid are ____ phases. Usually ____

A

liquid
fluid
continuous
flexible

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8
Q

Manipulation
Alginate (irreversible) Hydrocolloid

l Powder (one scoop \_\_\_\_: one measure water)
– Shake for \_\_\_\_

l Lower W/P ratio
– increases ____, tear resistance, and ____
– Decreases working and setting ____
– Decreases ____

l Cooling water
– ____ working and setting times

A

powder
aeration

strength
consistency
times
flexibility

increases

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9
Q

Manipulation
Alginate (irreversible) Hydrocolloid

l Effect of water temperature on the setting time of an alginate impression material
The higher the temperature, the faster the ____

A

set

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10
Q

Manipulation
Alginate (irreversible) Hydrocolloid

lInsufficient mixing
– ____ mix and poor recording of detail

lStorage in air or water results in dimensional change
– Undergo ____ upon loss or gain or water
– Storage in ____

A

grainy
shrinkage or expansion
100%

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11
Q 
Advantages
Alginate (irreversible) Hydrocolloid
l \_\_\_\_
l Easy to manipulate
l \_\_\_\_ tasting and clean
l Able to displace blood and body fluids 
l \_\_\_\_
l Easily poured in stone
l Can be used with \_\_\_\_ trays
l Long \_\_\_\_
A 
inexpensive
pleasant
hydrophilic
stock
shelf life
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12
Q 
Disadvantages
Alginate (irreversible) Hydrocolloid
lTears \_\_\_\_
– Low tear strength
lMust be poured \_\_\_\_
lLimited \_\_\_\_ reproduction lDimensionally \_\_\_\_
lCan only be used for \_\_\_\_
A 
easily
immediately
detail
unstable
single casts
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13
Q

(2)Agar (reversible) Hydrocolloid

l Largely replaced by ____ impression materials
l Uses
– Full mouth and quadrant impressions without
deep ____
l May be used for partial fixed dental prosthesis impressions because of their high ____

A

rubber
undercuts
accuracy

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14
Q 
Composition
Agar (reversible) Hydrocolloid
l Supplied as a \_\_\_\_ in plastic tubes
l Contains \_\_\_\_% water
l Can be converted to a sol (liquid) by \_\_\_\_
l \_\_\_\_ a sol causes it to become a gel
l Gel-to-sol and sol-to-gel transformations
dependent upon \_\_\_\_
A 
solid gel
85
heating
cooling
time and temperature
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15
Q 
Composition
Agar (reversible) Hydrocolloid
lLiquefaction and gelation temperatures are different
– Gelation (\_\_\_ temperature)
– Sol (\_\_\_temperature)

agar hydrocolloid (hot) agar hydrocolloid (cold)
heat to 100 to sol, cool to 43 to gel
lKnown as ___

A

lower
higher
hysteresis

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16
Q

Mechanical Properties
Agar (reversible) Hydrocolloid
lHighly ____ (98.8%) lSufficiently ____ (11%)
– For teeth with undercuts lStronger when stressed ____
– Rapid removal recommended

A

elastic
flexible
quickly

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17
Q 
Manipulation
Agar (reversible) Hydrocolloid
l Special water bath with 3 chambers for heating and water-cooled trays needed
– Liquefaction bath (1000C [2120F]) 
l\_\_\_\_ tray material
l\_\_\_\_ syringe material
– Storage bath (about 650C [1500F]) 
lMaintains \_\_\_\_ materials until needed
– Tempering bath (about 400C [1050F])
lReduces the temperature of the \_\_\_\_ tray material to avoid tissue damage
A

heavy-bodied
light bodied

liquefied
heavy-bodied

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18
Q 
Manipulation
Agar (reversible) Hydrocolloid
lPour \_\_\_\_
– Becomes less accurate during \_\_\_\_
– May store in \_\_\_\_for < 1 hour 
lImbibition
– \_\_\_\_ structure can absorb water
– May be accompanied by \_\_\_\_
A 
immediately
storage
100% humidity
gel
expansion
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19
Q

Advantages
Agar (reversible) Hydrocolloid

l \_\_\_\_
l Accurate and pleasant
l \_\_\_\_ and nonstaining
l Do not require a \_\_\_\_ or adhesives 
l Does not require mixing
l Hydrophilic
– Can be used in the presence of \_\_\_\_
– Can displace \_\_\_\_ and body fluids
l Easily poured in stone
l Stone casts easily \_\_\_\_ l Long \_\_\_\_
l Long \_\_\_\_ time
A 
inexpensive
non-toxic
custom tray
moisture
blood
removed
shelf life
working
20
Q 
Disadvantages
Agar (reversible) Hydrocolloid
l \_\_\_\_ equipment required l Must be prepared in \_\_\_\_l Tears easily
l Thermal \_\_\_\_
l Difficult to see margins and details l Must be poured \_\_\_\_
l Dimensionally unstable
l Can only be used for \_\_\_\_ casts
l For use only with \_\_\_\_
A 
expensive
advance
discomfort
immediately
single
stone
21
Q

Reference Tables
lDimensional change of hydrocolloid impressions (

TAKE A LOOK AT THE TABLE!

A

ok

22
Q

(3)Polysulfide Rubber

l Widely used for ____
– High ____
– Low ____
l Useful for ____ impressions when extra time is needed
l Tubes with base paste and catalyst l Low, medium and high ____

A 
fixed prostheses
accuracy
cost
multiple
viscosities
23
Q

Mechanical Properties
Polysulfide Rubber

l Flexibility
– More flexible than stiffer ____
– Removal from undercuts ____

l Tear strength
– ____ of a material to tearing forces
– Highest of rubber materials
– May use in ____ areas where removal difficult

A

addition silicones and polyethers
easier
resistance
subgingival

24
Q

Manipulation
Polysulfide Rubber
lBase and catalyst ____ lengths on mixing pad
– Lack of ____ in mix

lHigher temperatures and humidity ____ working and setting times
lPour within ____ due to shrinkage

A

equal
streaks
shortens
1 hour

25
Q

Advantages
Polysulfide Rubber

l Long \_\_\_\_
l Good \_\_\_\_
l Good flow before setting
l Good \_\_\_\_ of surface detail
l Margins easily seen
l High \_\_\_\_ for easier removal around undercuts
l Lower cost than silicones and polyethers
l Better \_\_\_\_ over hydrocolloid 
l Easier to pour than other elastomers
A 
working time
tear strength
reproduction
flexibility
dimensional stability
26
Q

Disadvantages
Polysulfide Rubber

l ____ needed due to greater chance of distortion
l Longer setting time-____min
l Bad ____
l Tendency to run down throat due to ____ viscosity
l ____ clothing (lead dioxide), messy
l Must pour within ____
l Cannot ____

A 
custom trays
10
odor
lower
stains
1 hour
repour
27
Q

(4a)Condensation Silicone Rubber

lMain use for partial fixed dental prostheses impressions
lIdeal for ____
lLow, medium, high and very high (putty) ____

A

single unit inlays

viscosities

28
Q

Mechanical Properties
Condensation Silicone Rubber

l Elastic recovery (99%)-____
l ____ flow
– Less distortion with ____ pressure on standing
l Lower ____ values
– Stiffer than ____
l High ____ (24 hours)
– Gives off ____ as byproduct of polymerization
– Immediate ____
– Reduced by putty first, and secondly ____

A 
excellent
low
light
flexibility
polysulfides
polymerization shrinkage
alcohol
pour
light body
29
Q 
Manipulation
Condensation Silicone Rubber
l Two \_\_\_\_ or paste-liquid catalyst
l \_\_\_\_ setting time than polysulfides (6-8
minutes)
l Must be poured \_\_\_\_
– High polymerization shrinkage
l Higher temperatures and humidity \_\_\_\_ setting time
A

paste
lower
immediately
shorten

30
Q

Advantages
Condensation Silicone Rubber

l ____, pleasant for patient
l Highly ____
l Good working time
l Setting time can be controlled with amount of ____
l Easily seen ____
l Putty-wash system improves ____ and eliminates need for custom tray

A 
clean
elastic
accelerator
margins
accuracy
31
Q 
Disadvantages
Condensation Silicone Rubber
l Pour within \_\_\_\_
– Shrinkage on standing
l \_\_\_\_
– Require a very dry field
l Difficult to pour in \_\_\_\_ (poor wetting) – often trap \_\_\_\_
l\_\_\_\_ may help
A 
1 hour
hydrophobic
stone
air bubbles
surfactant
32
Q

(4b)Addition (vinyl) Silicones (poly[vinyl siloxanes])

l Advance in accuracy over condensation silicones – Change in polymerization to ____
l Eliminates ____ by-product causing shrinkage
l For fixed and removable partial denture
impressions (____ accuracy)
l ____ system (____ viscosities) – Light, medium, heavy, putty
l ____ after setting
l ____ materials being introduced
– To improve ____ characteristics

A 
addition type
alcohol
high
two paste
4
rigid
hydrophilic
wetting
33
Q

Composition
Addition (vinyl) Silicones

l Prepolymers polymerized by ____ reaction
– No ____ by-products result in greater dimensional stability
l Hydrogen gas release may cause ____
l ____ may extend working and setting times

A

addition polymerization
volatile
porosity
retarder

34
Q

Mechanical Properties
Addition (vinyl) Silicones

l \_\_\_\_ working time than polysulfides
l Excellent \_\_\_\_
l Low dimensional \_\_\_\_ upon storage
– Pour later or send to laboratory 
l Greater rigidity (low \_\_\_\_)
– Difficult to remove around \_\_\_\_ 
l Tear strength
– Similar to \_\_\_\_
– Less than \_\_\_\_
A 
faster
elasticity
shrinkage
flexibility
undercuts
condensation silicones
polysulfides
35
Q

Manipulation
Addition (vinyl) Silicones

l____ absorber (finely divided Pd)
– If not present, wait ____ before pouring dies
l____ hours for epoxy dies
lAutomatic mixers available for quick, bubble ____ mixes

A

hydrogen
1 hour
24
free

36
Q

Advantages
Addition (vinyl) Silicones

l ____ accurate
l Easily seen ____
l Recovery from deformation on removal excellent
l Stays in tray of ____ patients
l Does not stain clothing
l ____ colors and scents
l May use custom or stock trays
l May pour ____ week after making impression – High dimensional ____ after setting
l ____ pours possible l Short setting time
l ____ available

A 
highly
margins
reclined
pleasant
1 week
stability
multiple
automix
37
Q

Disadvantages
Addition (vinyl) Silicones

l Expensive!
l Difficult to remove around ____ (rigid)
l Moderate tear strength
– Difficult to remove from ____ areas
l Hydrogen gas release may cause ____ on die surface
l ____ materials difficult to pour in stone
l Hydrophilic formulations imbibe ____
l ____ when in contact with moisture
l Sulfur in latex gloves and rubber dams can inhibit ____

A 
undercuts
gingival retraction areas
bubbles
hydrophobic
moisture
expand
polymerization
38
Q

(5)Polyethers
lUsed for a few ____ teeth without severe undercuts
lHigh ____ and ____ working time restricts use to a few teeth
lLow, medium, and high ____ materials

A

prepared
stiffness
short
viscosity

39
Q

Mechanical Properties
Polyethers

l Similar to \_\_\_\_ in properties 
l \_\_\_\_ working time (2.5 minutes)
l \_\_\_\_ time (4.5 minutes)
l Absorbs water and changes dimensions
– Cannot store in \_\_\_\_
l Low flexibility (high \_\_\_\_)**
– Problems with impression \_\_\_\_
– Problems with \_\_\_\_ removal from impression
l Low \_\_\_\_ strength values
A 
additional silicones
short
setting
water
stiffness
removal
die
tear
40
Q

Manipulation
Polyethers
lSimilar to ____ and silicones – ____ lengths base and catalyst
lAvoid contact of catalyst with ____ due to possible tissue reactions
lHandheld mixer available lAutomatic mixing device (Pentamix)

A

polysulfides
equal
skin or mucosa

41
Q

Advantages
Polyethers

 Pleasant handling
l Ease of mixing
l More \_\_\_\_ than polysulfide or condensation silicones
l Good \_\_\_\_ reproduction
l Easily poured in \_\_\_\_
l If kept dry, dimensionally stable x \_\_\_\_ wk 
l Fast setting
l Least \_\_\_\_
l Easily seen margins
l Shelf life: \_\_\_\_ years
l Automix available
A 
accurate
surface detail
stone
1
hydrophobic
2
42
Q

Disadvantages
Polyethers

l High ____
l ____ working time
l High ____ after setting l Need to block out undercuts l ____ taste
l Will distort if stored in ____
– Cannot be left in ____ for long periods

A 
cost
short
stiffness
bitter
water or high humidity
disinfectant
43
Q

Reference Tables
lProperties of elastomeric impression materials (Table 7-2)

YA

Reference Tables

l Handling properties of elastomeric impression materials (Table 7-3)

YA

A

YA

44
Q

Custom tray fabricatin

Pencil outline ____ apical from gingival margin

Adapt ____ baseplate wax over teeth and tissues to pencil line

Occlusal tray stops by cutting out a square

Foil can be added to prevent ____

Place ____ over wax

Remove Triad from pouch

A

2
2 sheets
resin contamination
MRA

45
Q

Custom Tray Fabrication

Adapt material to wax

Form handle 3⁄4􏰄 x 3⁄4􏰄 at ____o angle

Cure ____ minutes. Then, leave wax in tray cure ____ minute with ____ side up.

A

70
2
1
tissue

46
Q 
l Tray rigid
Criteria
  l Uniform thickness (\_\_\_\_mm)
l Tray extends \_\_\_\_ cervical to margins
l Tray extended properly in all areas
l Tray displays adequate rim lock
l Tray stable on cast
l Occlusal stops provide \_\_\_\_ thickness impression material
l Tray surface is finished and polished with rounded edges
l Secure and properly angled handle
l Accurate self assessment
F
A

2-3
3mm-5mm
2-3mm

Fixed Prosth, Module I (13 decks)

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