Impression Materials and Custom Tray Fabrication Flashcards by J L

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

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

How well did you know this?

Not at all

Perfectly

Types of Impression Material

Nonelastic

____
____
____

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

impression compound
plaster
zinc oxide-eugenol

alginate
agar
polysulfides
silicones
polyethers

How well did you know this?

Not at all

Perfectly

(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!

used
preliminary
study
orthodontic
accurate

How well did you know this?

Not at all

Perfectly

Composition
Alginate (irreversible) Hydrocolloid
l\_\_\_\_ and calcium sulfate dihydrate
– reactants
l\_\_\_\_
– Retarder
– Adjusted by the manufacturer to produce regular or fast \_\_\_\_

sodium or potassium alginate
reactants
set

How well did you know this?

Not at all

Perfectly

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

stiffness
potassium sulfate
gypsum
coloring

How well did you know this?

Not at all

Perfectly

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

sol

gel

How well did you know this?

Not at all

Perfectly

Composition

alginate (irreversible) hydrocolloid

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

Gel: Solid and liquid are ____ phases. Usually ____

liquid
fluid
continuous
flexible

How well did you know this?

Not at all

Perfectly

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

powder
aeration

strength
consistency
times
flexibility

increases

How well did you know this?

Not at all

Perfectly

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 ____

set

How well did you know this?

Not at all

Perfectly

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 ____

grainy
shrinkage or expansion
100%

How well did you know this?

Not at all

Perfectly

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 \_\_\_\_

inexpensive
pleasant
hydrophilic
stock
shelf life

How well did you know this?

Not at all

Perfectly

Disadvantages
Alginate (irreversible) Hydrocolloid
lTears \_\_\_\_
– Low tear strength
lMust be poured \_\_\_\_
lLimited \_\_\_\_ reproduction lDimensionally \_\_\_\_
lCan only be used for \_\_\_\_

easily
immediately
detail
unstable
single casts

How well did you know this?

Not at all

Perfectly

(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 ____

rubber
undercuts
accuracy

How well did you know this?

Not at all

Perfectly

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 \_\_\_\_

solid gel
85
heating
cooling
time and temperature

How well did you know this?

Not at all

Perfectly

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 ___

lower
higher
hysteresis

How well did you know this?

Not at all

Perfectly

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

elastic
flexible
quickly

How well did you know this?

Not at all

Perfectly

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

heavy-bodied
light bodied

liquefied
heavy-bodied

How well did you know this?

Not at all

Perfectly

Manipulation
Agar (reversible) Hydrocolloid
lPour \_\_\_\_
– Becomes less accurate during \_\_\_\_
– May store in \_\_\_\_for < 1 hour 
lImbibition
– \_\_\_\_ structure can absorb water
– May be accompanied by \_\_\_\_

immediately
storage
100% humidity
gel
expansion

How well did you know this?

Not at all

Perfectly

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

inexpensive
non-toxic
custom tray
moisture
blood
removed
shelf life
working

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 \_\_\_\_

expensive
advance
discomfort
immediately
single
stone

Reference Tables
lDimensional change of hydrocolloid impressions (

TAKE A LOOK AT THE TABLE!

(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 ____

fixed prostheses
accuracy
cost
multiple
viscosities

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

addition silicones and polyethers
easier
resistance
subgingival

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

equal
streaks
shortens
1 hour

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 ```

``` working time tear strength reproduction flexibility dimensional stability ```

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 ____

``` custom trays 10 odor lower stains 1 hour repour ```

(4a)Condensation Silicone Rubber lMain use for partial fixed dental prostheses impressions lIdeal for ____ lLow, medium, high and very high (putty) ____

single unit inlays | viscosities

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 ____

``` excellent low light flexibility polysulfides polymerization shrinkage alcohol pour light body ```

``` 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 ```

paste lower immediately shorten

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

``` clean elastic accelerator margins accuracy ```

``` 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 ```

``` 1 hour hydrophobic stone air bubbles surfactant ```

(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

``` addition type alcohol high two paste 4 rigid hydrophilic wetting ```

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

addition polymerization volatile porosity retarder

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 ____ ```

``` faster elasticity shrinkage flexibility undercuts condensation silicones polysulfides ```

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

hydrogen 1 hour 24 free

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

``` highly margins reclined pleasant 1 week stability multiple automix ```

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 ____

``` undercuts gingival retraction areas bubbles hydrophobic moisture expand polymerization ```

(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

prepared stiffness short viscosity

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 ```

``` additional silicones short setting water stiffness removal die tear ```

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)

polysulfides equal skin or mucosa

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 ```

``` accurate surface detail stone 1 hydrophobic 2 ```

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

``` cost short stiffness bitter water or high humidity disinfectant ```

Reference Tables lProperties of elastomeric impression materials (Table 7-2) YA Reference Tables l Handling properties of elastomeric impression materials (Table 7-3) YA

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

2 2 sheets resin contamination MRA

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.

70 2 1 tissue

``` 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 ```

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

Brainscape's Knowledge GenomeTM

Impression Materials and Custom Tray Fabrication Flashcards

Brainscape's Knowledge Genome^TM