Non Elastic Impression Pt. 2

Question 1

Name nonelastic impression materials

Answer 1

1. Impression plaster
2. impression compound
3. zinc oxide eugenol impression paste
4. compression waxes

Question 2

Name the components of impression plaster

Answer 2

1. Main ingredient - beta calcium sulphate hemi hydrate
2. anti-expansion agent - potassium sulphate
3. retarder - borax
4. pigment - Alazarin red 

Question 3

What are the manipulative variables of impression plaster

Answer 3

1. High water powder ratio
2. special tray

Question 4

What are the advantages of impression plaster

Answer 4

1. Mucostatic impression technique
2. Hydrophilic
3. Accuracy
4. Minimal dimensional change

Question 5

What are the disadvantages of impression plaster

Answer 5

1. Dryness of mouth
2. Very brittle
3. not suitable for recording undercuts
4. difficult to remove

Question 6

How do you disinfect impression plaster

Answer 6

10 minutes soaked in 10% sodium hypo chlorite solution

Question 7

What’s the use of impression plaster

Answer 7

patients with excessively mobile soft tissues overlying the residual alveolar bone

Question 8

Which nonelastic impression materials are thermoplastic

Answer 8

1. Impression compound
2. Impression waxes

Question 9

What is the function of filler in impression compound

Answer 9

1. increasing viscosity of the softened material
2. reduces thermal contraction

Question 10

What is the function of lubricant in impression compound

Answer 10

Improves flow properties

Question 11

What is the composition of impression compound

Answer 11

1. Thermal plastic material 47% natural or synthetic raisins and waxes
2. filler 50% Talc
3. Lubricant 3% stearic acid

Question 12

What are the uses of the different types of impression compounds

Answer 12

1. Type one- low fusing and medium fusing: Used as impression material, Border extension and single crown impression
2. Type two - higher fusing: used to construct impression trays

Question 13

What is copper ring technique

Answer 13

It is use from making an impression of a single crown. Copper tube is used. It’s places around the tooth and acts as a tray. Type one impression compound is softened and pressed over the tooth in the ring. electroform dies

Question 14

What are the factors affecting performance of impression compound Sheet form during manipulation

Answer 14

1. Conditioning temperature
2. time of conditioning in water bath

Question 15

What is the ideal conditioning temperature for impression compound sheet form

Answer 15

55 to 60°C

Question 16

What are the properties of impression compound

Answer 16

1. Flow
2. Viscosity
3. rigidity
4. poor Elastic properties
5. Cannot be used for undercuts
6. large value of coefficient of thermal expansion

Question 17

What are the three factors that combine to produce significant internal stress is within the impression compound

Answer 17

1. High value of coefficient of thermal expansion
2. poor thermal conductivity
3. high temperature drop from softening temperature room temperature

Question 18

What is the composition of zinc oxide eugenol paste one

Answer 18

1. Zinc oxide
2. olive oil, linseed oil or equivalent
3. zinc acetate
4. water

Question 19

What is the composition of paste two zinc oxide eugenol 

Answer 19

1. Eugenol (oil of cloves)
2. Kaolin, talc or equivalent

Question 20

What is the function of zinc acetate and water in zinc oxide eugenol 

Answer 20

To accelerate setting

Question 21

What is the function of kaolin/ talc in zinc oxide eugenol paste

Answer 21

Inert filler used to make a paste

Question 22

How do you Accelerate the setting reaction of zinc oxide eugenol 

Answer 22

1. Increasing temperature
2. increasing humidity
3. Presence of water and certain ionizable salts
4. Speculation time (the longer the paste is mixed the quicker it will set)

Question 23

What is the nature of the setting reaction of zinc oxide eugenol?

Answer 23

Ionic

Question 24

What are the properties of zinc oxide eugenol 

Answer 24

1. Low viscosity
2. pseudo plastic nature
3. Easy manipulation
4. rigid
5. good dimensional stability

Question 25

What are the disadvantages of zinc oxide eugenol

Answer 25

1. Allergies to eugenol 2. Distort or fracture when remove from undercuts 3. lack of elasticity 4. Sticky and adheres to tissues 5. only sets quickly in thin sections 6. requires a special tray

Question 26

What are the applications of nonelastic impression materials

Answer 26

1. No undercuts 2. Edentulous patients

Question 27

Which Nonelastic impression material is reversible

Answer 27

Impression compound

Question 28

What are the advantages of impression Compound

Answer 28

1. Non-irritant and nontoxic 2. reusable in the same patient 3. can be reheated and re adopted 4. support other materials for wash impression 5. can be electroplated

Question 29

What are the disadvantages of impression compound

Answer 29

1. Poor Surface detail 2. distortion occurs when removed from undercuts 3. poor dimensional stability

Question 30

What are the uses of zincoxide eugenol impression pastes 

Answer 30

1. Impressions of EDENTULOUS ridges 2. bite registration 3. spotting denture sore spots 4. fixing occlusal blocks during jaw relation. 

Question 31

What is the water: powder ratio for impression plaster

Answer 31

50 to 60 ml :100 mg

Question 32

What is the percentage of expansion that occurs when impression plasters mix with water. What will be the percentage when mixed with anti-expansion solution

Answer 32

0.3% to 0.6% 0.05%

Question 33

Which Non-elastic impression material is mucostatic 

Answer 33

Impression plaster Impression wax