All Free Dental Materials MCQs with Answers

• 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…

• A. Polysulphide > polyether > Condensation silicone > Addition silicone
• B. polyether > Condensation silicone > Polysulphide > Addition silicone
• C. Addition silicone > polyether > Polysulphide > Condensation silicone
• D. Addition silicone> Condensation silicone > Polysulphide > polyether

Explanation: Addition silicone has the best dimensional stability because it produces no volatile by-product, followed by polyether, polysulfide and…

• A. Chilled alginate and impression compound
• B. Syringe agar and tray agar
• C. Syringe agar and impression compound
• D. Syringe agar and chilled tray alginate

Explanation: The laminate technique combines syringe agar for fine detail with chilled tray alginate as the supporting material.

• A. Addition silicone < polyether < polysulfide < condensation silicone
• B. Addition silicone < polysulfide < Polyether < condensation silicone
• C. condensation silicone < polyether < polysulfide < Addition silicone
• D. condensation silicone < polysulfide < polyether < Addition silicone

Explanation: Linear contraction generally increases from addition silicone to polyether, polysulfide and condensation silicone.

• A. After the start of appearing elastic properties of impression material
• B. Just after the start of appearing elastic properties of impression material
• C. The time for start of mixing till just before the start of appearing elastic properties of impression material
• D. Loss of lusture of impression material

Explanation: Working time is measured from the beginning of mixing until the material starts developing elastic properties.

• A. 4% Potassium sulfate
• B. 0.2% Potassium sulfate
• C. 2% sodium sulfate
• D. 2% Potassium sulfate

Explanation: A 2% potassium sulfate solution is used as a surface hardener for some impression materials, particularly to improve the surface hardness…