Free Impression Materials MCQs with Answers

• A. 4%
• B. 6%
• C. 8%
• D. 10%

Explanation: Type I impression compound must show at least about 6% flow at mouth temperature so it can adapt adequately to oral tissues.

• A. Unpleasant odor and taste
• B. Low accuracy
• C. Least permanent deformation
• D. Highest curing shrinkage

Explanation: Polysulfide impressions are avoided routinely because they have an unpleasant odor and taste and require a relatively long setting time.

• A. Hysterisis
• B. Recrytallisation
• C. Imbibition
• D. Syneresis

Explanation: Hydrocolloids characteristically show hysteresis, syneresis, and imbibition, which explain their temperature-dependent gelation and…

• A. Zinc oxide eugenol
• B. Alginate
• C. Impression compound
• D. Plaster of paris

Explanation: Impression compound hardens by physical cooling rather than by a chemical reaction, so it can be softened and reused.

• A. Putty used first and light body used second
• B. Light body and putty used at the same time
• C. Light body first and putty later
• D. None of the above

Explanation: In the two-stage putty-wash technique, putty is used first to form the preliminary support and space, followed by light-body material to…

• A. Inadequate mixing
• B. Air bubbles
• C. Incomplete polymerization caused by premature removal from mouth
• D. Too rapid polymerization

Explanation: Premature removal can leave the elastomer incompletely polymerized and produce a rough or defective impression surface.

• A. Condensation silicone
• B. Polysulphide
• C. Addition silicone
• D. Polyether

Explanation: Polyether is the most rigid of the commonly used elastomeric impression materials because its set polymer has a high modulus and low…

• A. Addition silicone
• B. Polyether
• C. Polysulphide
• D. Condensation silicone

Explanation: Addition silicone, or polyvinyl siloxane, has the greatest elastic recovery among these materials, usually around 99% or more.

• A. Condensation silicone
• B. Poly vinyl siloxane
• C. Polysulfide
• D. Polyether

Explanation: Polyvinyl siloxane is an addition-cured silicone whose platinum catalyst is commonly supplied as chloroplatinic acid or a related platinum…

• A. After the start of appearing elastic properties of impression material
• B. Just after the start of appearing elastic properties of impression material
• C. Just before the start of appearing elastic properties of impression material
• D. Loss of luster of impression material

Explanation: Working time extends from the start of mixing until the material begins to develop elastic behavior, so manipulation should be completed…

• A. Calcium alginate
• B. Potassium alginate
• C. Trisodium phosphate
• D. Sodium alginate

Explanation: Alginate gel forms when soluble alginate reacts with calcium ions to produce insoluble calcium alginate.

• A. Reducing the diatomaceous earth
• B. Coating with dihydric alcohol
• C. Adding heavy metal salts
• D. Altering the matrix

Explanation: Dustless alginate is made by coating the fine powder particles with a glycol or other dihydric alcohol, reducing airborne dust during…

• A. Zinc Oxide eugenol impression paste
• B. Hydrocolloid impression material
• C. Elastomeric impression material
• D. All of the above

Explanation: Elastomeric materials can be used in a simultaneous two-viscosity technique, such as putty with light-body material, allowing the…

• A. Injecting technique
• B. Tempering technique
• C. Immersion technique
• D. Laminate technique

Explanation: The laminate technique combines reversible agar with irreversible alginate, with the agar layer bonded to the alginate.

• A. Too rapid polymerization
• B. Air incorporated during mixing
• C. Improper application of pressure during impression making
• D. Presence of moisture in impression area

Explanation: If an impression material polymerizes too rapidly, it cannot flow and adapt smoothly to the oral tissues, producing a rough or irregular…

• A. Plaster of paris
• B. Agar - agar
• C. Zinc oxide eugenol
• D. Elastomers

Explanation: Impression plaster has the lowest viscosity among these choices, so it flows readily over tissues and into fine surface details.

• A. Silicones, hydrocolloids, polyether, polysulfide
• B. Hydrocolloids, silicones, polyether, polysulfide
• C. Polysulfide, hydrocolloids, silicones, polyether
• D. Hydrocolloids, polyether, silicones, polysulfide

Explanation: Hydrocolloids have the weakest tear resistance, while polysulfide has the greatest; silicones and polyether lie between them.

• A. Impression compound
• B. Alginate
• C. Elastomer
• D. ZOE paste

Explanation: Zinc oxide eugenol is mucostatic because it records tissues with minimal displacement when used in a passive, unsupported impression.

• A. Ethyl alcohol
• B. Glycol
• C. Acetate
• D. Propanolol

Explanation: Condensation silicone reacts with an alkyl silicate cross-linker and releases ethyl alcohol as a volatile by-product.

• A. Zinc chloride & Eugenol
• B. Zinc Sulphate & Zinc chloride
• C. Zinc Sulphate & Eugenol
• D. Glycerin

Explanation: Zinc chloride and zinc sulfate can accelerate the zinc oxide eugenol setting reaction, whereas glycerin acts mainly as a plasticizer or…