Elastic Impression

Question 1

non aquas Elastomeric

Answer 1

Groub of synthtic polymer that atr vhemicaliy cross linked and can be streched and returns to its original shape

Question 2

Non-aqueous Hydrocolloids

Answer 2

Dif in the setting meachnism and physical and chemical properties

Base paste + base catalist = either by product or not

Question 3

Polysulfides

Answer 3

Has a base filler and
Catalist or reacter filler - lead dioxide - gives strenght and brown stain

Question 4

Polysulfides raction

Answer 4

It has a water by product

Lossing of the material can affect the dimintional stability of the impression

Question 5

Polysulfides
Proprties

Answer 5

Working time/ 5-7 which is the longest amoung the elastomers
Setting time /8-12 long
High tear strenth and elastic proprties

Question 6

Why the Polysulfides not liked by the paitents

Answer 6

Odor taste
Long setting time
Premanent stain on the clothes -Lead peroxides-

Question 7

Polysulfides
Clinical Tips During Manipulation

Answer 7

Humdifiy and tm decrease the working time
Hydrophobic - nomouiseter during preparation
Slight contraction during polymrizition - costum impression tray-

Question 8

Polysuflied For maximum accuracy,

Answer 8

Pouring the cast: impression must be poured within 30 min. to 1 hr.

Question 9

Condensation Silicone material

Answer 9

2 paste system
2 putty system

Question 10

Two putty system

Answer 10

Putty used as a tray in conjction with the lo viscosty silicon
Putty wash technique

Question 11

Condensation Silicone by product

Answer 11

Eythel-alchol and wen its evaporate it will cause contraction of the impression

Question 12

Condensation Silicone
Properties:
• OVERCOME some of polysulfide’s disadvantages

Answer 12

Odorless and pigmented
Less setting time / 6-8 min
Less afected by the heat and tm / humidity

Question 13

Who’s more stable

Answer 13

The polysufied more stable than the condensition silicon but the silicon moe stable than the reversible hydrocolloid

Question 14

Condensation Silicone
Clinical Tips During Manipulation

Answer 14

Its hydrophobic in nature during the pouring its harder to avoid air bubbles in con silicon than any other elastomric material

Question 15

Addition Silicone

Answer 15

Polyvinyl Siloxane (PVS)——-Vinyl Polysiloxane (VPS)
§ The base paste contains:
- Polymethylhydrosiloxane
- Divinylpolysiloxane.
§ The catalyst (or accelerator) paste contains:
- Divinylpolysiloxane
- Platinum salt.

Question 16

Addition silicon by product

Answer 16

It has no byproduct so its dimintionally stable

But if there is any reminings from the polyether then a 2nd reaction will happen which will produce hydrogen gas and still wont affect the stability

Question 17

Addition Silicone
Properties:
Similar to condensation silicone in may aspects, EXCEPT

Answer 17

Affected by the tm
More dimintionly stable

Question 18

Addition Silicone
Properties: abt the hydrophobic

Answer 18

Some formulition has a hydrophilic proprties Surfactant/ Surfactant migrates toward the surface of the impression material and makes the surface more wettable by water.

Question 19

Addition Silicone
Clinical Tips During Manipulation

Answer 19

• Delayed Pouring (Earlier product)
  Hydrogen gas evolved result in > pinpoint voids in the gypsum casts poured soon after removal of the impression from the mouth.

-Immediate Pouring (Newer product)
Manufacturers may add a noble metal, such as palladium, as a scavenger for the released hydrogen gas

-No latex gloves during mixing
§ Setting inhibition caused by some brands of latex gloves

Question 20

Polyether

Answer 20

§ The material is supplied as two pastes

The base paste contains:
- the polyether polymer,
- Filler: colloidal silica
- Plasticizer : glycol ether or phthalate.

The accelerator paste contains: - an alkyl-aromatic sulfonate
- in addition to Filler &Plasticizer

Question 21

Polyether byproducts

Answer 21

None

Question 22

Polyethyer Properties:

Answer 22

Short working time / decreased the number of teeth that will be captured during one impr
Short setting time
Stefness of the matirial
Alrergic reaction

Question 23

Properties of the polyether

Answer 23

Hydrophilic in natrure
Stable only if stored dry

Question 24

VPES

Answer 24

New impresion
Polyeteh+vps

Excelent flow
High tear strenght
Hydrophilicty
Elastisty

Question 25

Making impressions with elastomeric materials Fabrication of gypsum models ,casts and dies involves 6 major steps:

Answer 25

1- prepare the try 2-prepare the tissue 3-prepare the matirial 4-taking the impression 5-remove the impression 6-prepare the stone cast

Question 26

Prepare the tray

Answer 26

To use less impression matirial as possible Equal distribution of the impresion between the object and the tray -Especially for polysulfide impression material- In case of severe undercuts the tray is avoided Adhesive application Prior to impression making, uniform thickness of adhesive should be applied to the tray

Question 27

Prepare the tissue

Answer 27

Gingival retraction cord to displace the gingival tissue laterally away from the margin of the preparation.

Question 28

Manipulation Of Impression Materials

Answer 28

§ Hand mixing § Static mixing § Dynamic mechanical mixing

Question 29

This technique transforms two fluid (or paste-like) materials into a homogeneous mixture without mechanical mixing

Answer 29

Static mixing

Question 30

Device uses motor to drive parallel plungers, forcing the materials into a mixing tip and out into an impression tray or syringe.

Answer 30

Dynamic mechanical mixing

Question 31

Making the Impression - multible mix techniqe

Answer 31

Light body - syrenige Heavy body- tray

Question 32

Multiple-mix technique

Answer 32

One step> light paste on the prepared tooth and over the tray which has the heavy body then take the impreasion by one step 2 steps > adhisve on the tray heavy body on the tray and take the ipressionn then place the light material on the prepared tooth then over the tray and take the impression again

Question 33

Monophase technique

Answer 33

Meduim body Polyether and addition silicon

Question 34

Monophase mixing

Answer 34

Only one mixture is made and a part of the material is placed in the tray and another portion in syringe for injection in the prepared tissues.—-> which will makes its viscisty to reduse and it will easliy flow over the teeth and tray

Question 35

Putty-wash technique

Answer 35

Condensation silicone - To minimize the effect of associated dimensional changes .

Question 36

Removal of the impression

Answer 36

Remove after completly cured Impression should be ready for removal within at least 10 min from time of mixing, allowing 6-8 min for impression to remain in mouth.

Question 37

Remove the impression

Answer 37

The first step: is to break the addhision between the impression and tray Second step: stretch the impression to drive at the height of contour

Question 38

has the lowest viscosity and ranks as one of the least stiff of the elastomeric impression materials of a similar consistency.

Answer 38

Polysulfide

Question 39

All elastomeric impression materials are viscoelastic, and it is necessary to use a quick snap to minimize plastic deformation of the impression during the final step of the removal

Answer 39

Impo