Free Impression Materials MCQs with Answers

• A. Primary impression
• B. None of the above
• C. Impression of single tooth
• D. Corrective impressions

Explanation: Impression waxes are used mainly for corrective or relining impressions because they can be softened and adapted over an existing…

• A. Utility wax
• B. Base plate wax
• C. Beading wax
• D. Boxing wax

Explanation: Utility wax can be added to the borders of a stock tray to extend and adapt its contour around the arch.

• A. Modeling wax
• B. Iowa wax
• C. Green stick wax
• D. None of the above

Explanation: Iowa wax is a mouth-temperature impression wax that softens at intraoral temperature and can record tissues with minimal discomfort.

• A. It should be rapidly displaced from the mouth
• B. It will take up water and expand if kept wet
• C. It may exhibit fluid exudates on the surface as a result of imbibition of water
• D. It will shrink as a result of syneresis

Explanation: Surface fluid exudation is caused by syneresis, the loss of water from an alginate gel, not imbibition.

• A. Their hardness after setting
• B. Their use
• C. Water content
• D. Eugenol content

Explanation: Type I zinc oxide eugenol impression paste sets harder, whereas Type II sets softer and is easier to remove from undercut areas.

• A. Syneresis
• B. Imbibition
• C. Hysteresis
• D. Gelation

Explanation: Imbibition is the absorption of water by an alginate gel, producing expansion.

• A. Polysulphide
• B. Agar-agar
• C. Addition poly silicone
• D. Polyether

Explanation: Addition silicone has excellent dimensional stability because it produces no volatile alcohol by-product during setting.

• A. Acts as plasticizer
• B. Helps as surfactant
• C. Act as a scavenger
• D. Acts as a catalyst

Explanation: Palladium absorbs the hydrogen released during the setting reaction of some addition silicones, acting as a scavenger and preventing…

• A. A and B
• B. Addition Polysilicon
• C. Polyether
• D. Condensation polysillicon

Explanation: Immediate pouring is most critical with condensation silicone because its setting reaction releases volatile ethyl alcohol, causing…

• A. Low viscosity elastomeric impression material
• B. Medium viscosity elastomeric impression material
• C. High viscosity elastomeric impression material
• D. None of the above

Explanation: Low-viscosity elastomer flows readily around the prepared margins of abutment teeth and records fine detail.

• A. Non-elastic impression material
• B. Thermoplastic impression material
• C. Less mucostatic than ZOE
• D. More mucostatic than ZOE

Explanation: Alginate is relatively mucocompressive because it must be seated under pressure, whereas zinc oxide eugenol flows with less pressure and…

• A. High viscosity elastomer
• B. Medium viscosity elastomer
• C. Medium & low viscosity elastomer
• D. Low viscosity elastomer

Explanation: Syringe material must flow easily into the sulcus and around fine tooth details, so it is a low-viscosity elastomer.

• A. Hydro-colloid
• B. Modelling compound
• C. Impression wax
• D. Hydro cal

Explanation: A hydrocolloid, usually alginate, is commonly used for the preliminary or diagnostic cast because it is elastic, inexpensive, and records…

• A. Mechanical action of saliva
• B. Physical change
• C. Evolution
• D. Chemical change

Explanation: Agar changes between sol and gel by heating and cooling, so its setting is a physical change.

• A. Irreversible hydrocolloid
• B. Impression plaster
• C. Reversible hydrocolloid
• D. Metallic oxide paste

Explanation: Reversible hydrocolloid, mainly agar, shows hysteresis because its liquefaction temperature is higher than its gelation temperature.

• A. None of the above
• B. Using excess water for maxing
• C. Lowering the temperature of water used for mixing
• D. Raising the temperature of water used for maxing

Explanation: Warmer mixing water accelerates the chemical reaction of alginate and therefore shortens its setting time.

• A. Become elastic
• B. Continue to polymerize
• C. Show imbibition and syneresis
• D. Show gelation

Explanation: Rubber base impressions should be poured promptly because polymerization and continued dimensional change can produce shrinkage and…

• A. Free flowing wax
• B. Zinc oxide eugenol impression paste
• C. Thin mix of plaster of paris
• D. Reversible hydrocolloids

Explanation: A thin mix of impression plaster is highly mucostatic because it flows with minimal pressure and records tissues in their undisturbed…

• A. Slight rocking of the impression to disengage it from the undercut
• B. Wetting the periphery of the impression with moist cotton to break the peripheral seal
• C. Supporting the impression along with the tray to prevent disengaging of the tray alone
• D. Sudden jerking of the impression to prevent tearing

Explanation: A hydrocolloid impression should be removed with a quick, decisive movement along the path of removal, which reduces prolonged deformation…

• A. Increase flow
• B. Decrease flow
• C. Accelerate reaction
• D. Decrease irritation due to eugenol

Explanation: Lanolin acts as a plasticizer in zinc oxide-eugenol paste, lowering its viscosity and making the paste flow more readily.