Impression Materials Most Important MCQs

1 - 4th state of matter is______________?

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A. Solid

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B. Liquid

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C. Gas

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D. Colloid

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Colloid

2 - Agar impression materials differ from alginate impression materials in that the former sets by_______________?

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A. Mechanical action of saliva

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B. Physical change

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C. Evolution

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D. Chemical change

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Physical change

3 - Agar is prepared from_______________________?

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A. Bullock heart

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B. Chemicals

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C. Sea weed

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D. Chick cells

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Sea weed

4 - Alginate impression material is________________?

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A. Non-elastic impression material

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B. Thermoplastic impression material

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C. More mucostatic than ZOE

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D. Less mucostatic than ZOE

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Less mucostatic than ZOE

5 - Alginates are_____________?

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A. Sol

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B. Gel

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C. Hydrocolloid

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D. Colloid

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Hydrocolloid

6 - All of the following statements about an alginate impression are EXCEPT________________?

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A. It should be rapidly displaced from the mouth

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B. It may exhibit fluid exudates on the surface as a result of imbibition of water

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C. It will take up water and expand if kept wet

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D. It will shrink as a result of syneresis

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It may exhibit fluid exudates on the surface as a result of imbibition of water

7 - During setting of alginate impression materials________________?

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A. Trisodium phosphate reacts with sodium alginate

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B. Trisodium phosphate reacts with calcium sulphate

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C. Colloidal changes to sol

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D. Material in contact with soft tissues sets last

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Trisodium phosphate reacts with calcium sulphate

8 - Immediate pouring of impressions is most critical in_____________?

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A. Condensation polysillicon

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B. Addition Polysilicon

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C. Polyether

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D. A and B

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Condensation polysillicon

9 - In reversible hydrocolloid the property by which the transformation from sol to gel and gel to sol is a function of the_____________?

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A. Concentration of filler and plasticizer

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B. Percentage composition by weight of water

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C. Concentration of potassium sulphate

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D. Temperature

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Temperature

10 - K2SO4 in agar-agar is for_______________?

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A. Accelerating the setting stage of gypsum

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B. Increase strength

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C. Give dimensional stability

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D. None of the above

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Accelerating the setting stage of gypsum

11 - Lenolin is added is ZOE paste to______________?

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A. Decrease flow

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B. Increase flow

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C. Accelerate reaction

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D. Decrease irritation due to eugenol

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Increase flow

12 - Linear contraction of elostomeric impression with passage of time is highest in______________?

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A. Addition silicone

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B. Polysulphide

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C. Polyetner

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D. Condensation silicone

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Condensation silicone

13 - Name the accelerator used in Zinc oxide eugenol paste______________?

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A. Olive oil

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B. Linseed oil

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C. Zinc acetate

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D. All of these

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Zinc acetate

14 - Palatal secretions affect the setting of all the impression materials except_______________?

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A. Silicone

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B. Agar-agar

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C. Impression paste

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D. Impression plaster

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Agar-agar

15 - Palladium is added to polyvinyl siloxane to_____________?

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A. Act as a scavenger

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B. Helps as surfactant

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C. Acts as plasticizer

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D. Acts as a catalyst

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Act as a scavenger

16 - Perforated impression tray are used for_______________?

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A. Alginate

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B. Zinc oxide-eugenol

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C. Agar-agar

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D. Impression compound

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Alginate

17 - Retarder in Zinc oxide eugenol is______________?

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A. CaCl2

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B. Zinc acetate

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C. Alcohol

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D. Glycerine

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Glycerine

18 - Rinsing of the impression is important to________________?

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A. Remove excess impression material

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B. Remove saliva

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C. Hydrate the impression

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D. Accelerate the setting

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Remove saliva

19 - Rubber base impressions are poured immediately as they_______________?

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A. Continue to polymerize

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B. Become elastic

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C. Show imbibition and syneresis

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D. Show gelation

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Continue to polymerize

20 - Syneresis is associated with______________?

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A. Hydrocolloids

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B. Elastomers

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C. Zinc oxide eugenol

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D. Plaster of paris

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Hydrocolloids

21 - Syringe material is______________?

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A. High viscosity elastomer

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B. Medium viscosity elastomer

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C. Medium & low viscosity elastomer

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D. Low viscosity elastomer

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Low viscosity elastomer

22 - The advantage of ZOE impression paste_______________?

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A. Has dimensional stability

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B. Does not adhere to tissues

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C. Is easy manipulation

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D. Does not require special trays

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Has dimensional stability

23 - The best way to remove a hydrocolloid impression from the patient's mouth is____________?

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A. Slight rocking of the impression to disengage it from the undercut

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B. Wetting the periphery of the impression with moist cotton to break the peripheral seal

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C. Sudden jerking of the impression to prevent tearing

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D. Supporting the impression along with the tray to prevent disengaging of the tray alone

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Sudden jerking of the impression to prevent tearing

24 - The cross linking agent of polysulphide rubber base impression material is______________?

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A. Aromatic sulfonate esters

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B. Stannous octate

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C. Platinum salt catalyst

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D. Lead dioxide

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Lead dioxide

25 - The impression for a diagnostic cast of a partial edentulous mouth should be taken in_______________?

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A. Impression wax

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B. Modelling compound

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C. Hydro-colloid

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D. Hydro cal

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Hydro-colloid

26 - The impression material used to record the prepared areas on abutment teeth is______________?

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A. High viscosity elastomeric impression material

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B. Medium viscosity elastomeric impression material

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C. Low viscosity elastomeric impression material

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D. None of the above

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Low viscosity elastomeric impression material

27 - The impression with the least dimensional change upon disinfection is_______________?

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A. Addition poly silicone

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B. Agar-agar

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C. Polysulphide

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D. Polyether

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Addition poly silicone

28 - The most mucostatic impression material is_______________?

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A. Thin mix of plaster of paris

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B. Zinc oxide eugenol impression paste

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C. Free flowing wax

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D. Reversible hydrocolloids

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Thin mix of plaster of paris

29 - The plasticizers used in polyether impression material is_______________?

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A. polyether polymer

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B. Colloidal silica

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C. Glycol ether

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D. Di-vinyl poly (dimethyl siloxane)

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Glycol ether

30 - The setting time of irreversible hydrocolloids can be decreased by_____________?

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A. Raising the temperature of water used for maxing

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B. Using excess water for maxing

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C. Lowering the temperature of water used for mixing

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D. None of the above

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Raising the temperature of water used for maxing

31 - The term given to the phenomenon of moisture absorption by an alginate impression in________________?

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A. Imbibition

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B. Syneresis

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C. Hysteresis

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D. Gelation

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Imbibition

32 - The water powder ratio of alginate is______________?

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A. 100 ml of water to 60 gms of powder

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B. 40 ml of water to 40 gms of powder

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C. 40 ml of water to 15 gms of powder

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D. 15 ml of water to 40 gms of powder

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40 ml of water to 15 gms of powder

33 - Type I and Type II zinc oxide impression paste differ with respect to_______________?

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A. Their use

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B. Their hardness after setting

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C. Water content

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D. Eugenol content

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Their hardness after setting

34 - Wash or corrective impression is done by______________?

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A. Impression plaster

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B. Impression paste

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C. Alginate

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D. Rubber base impression material

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Impression paste

35 - When making a polysulphide impression for a caste crown, custom trays are usually preferred over stock trays for all of the following reasons except_______________?

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A. Custom trays facilitate uniform contraction of impression material

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B. Custom trays require less impression material

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C. Stock trays may be short in the flange area

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D. Impressions made n the custom trays are easier to remove from the mouth

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Impressions made n the custom trays are easier to remove from the mouth

36 - Which is best material for RPD impression_______________?

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A. Impression plaster

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B. Irreversible hydrocolloid

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C. Reversible hydroollioid

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D. None of the above

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Irreversible hydrocolloid

37 - Which material undergoes hysteresis ?

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A. Irreversible hydrocolloid

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B. Reversible hydrocolloid

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C. Impression plaster

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D. Metallic oxide paste

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Reversible hydrocolloid

38 - Which of the following is not affected by saliva ?

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A. Impression plaster

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B. Impression paste

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C. Silicon impression material

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D. None of the above

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None of the above

39 - Which of the following is true about Agar hydrocolloid impression material ?

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A. Liquefies between 71 – 100°C

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B. Solidfies between 50 – 70°C

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C. Facilitates fabrication of metal dyes

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D. Cannot register fine surface details

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Liquefies between 71 – 100°C

40 - Which one of the following increase the strength and reduce viscosity of agar hydrocolloid impression material_____________?

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A. Borax

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B. Water

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C. Sulfates

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D. Carbonates

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Borax

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