Free Restorative Materials MCQs with Answers

• A. 13-30%
• B. 0-6%
• C. 10-12%
• D. 20-30%

Explanation: High-copper amalgam contains approximately 12% to 30% copper, with the usual classification threshold being more than 6% copper.

• A. One to two minutes
• B. Three to four minutes
• C. Five to six minutes
• D. Seven to eight minutes

Explanation: Amalgam normally has a working time of about 3 to 4 minutes, during which trituration, insertion, condensation, and carving should be…

• A. Resistance to creep
• B. Dimensional Stability
• C. Better handling property
• D. Toxicity to pulp and dentin

Explanation: Zinc is added mainly to improve the handling and working characteristics of amalgam.

• A. Tarnish
• B. Dry corrosion
• C. Wet corrosion
• D. Tarnish and corrosion

Explanation: Silver-alloy discoloration results from both tarnish, which is surface chemical discoloration, and corrosion, which involves material…

• A. Delayed expansion
• B. Shrinkage
• C. Marginal breakdown
• D. increased stresses

Explanation: Moisture contamination of zinc-containing amalgam produces delayed expansion, commonly through hydrogen gas formation during the setting…

• A. Gamma 1
• B. Gamma 2
• C. Gamma 1 and 2
• D. No phase is eliminated

Explanation: High-copper amalgam uses copper to react with tin and prevent formation of the weak gamma-2 phase.

• A. Both require same condensing force
• B. More condensing force is required
• C. Less condensing force is required
• D. Manipulation is easy

Explanation: Spherical alloy particles have less interparticle friction and flow more readily, so they require less force for condensation than…

• A. Ingestion while removing old amalgam
• B. Skin contact
• C. Mercury vapour
• D. All of the above

Explanation: Chronic mercury toxicity can follow inhalation of mercury vapour, ingestion of mercury-containing material, or absorption through the…

• A. Tarnish and corrosion
• B. Cause fracture of the filling
• C. Increase the strength
• D. Decrease condensation pressure

Explanation: Excess residual mercury leaves more unreacted mercury-rich matrix, which weakens amalgam and increases creep, making fracture more likely.

• A. It has increased tensile and compressive strength
• B. It's edge strength is greater
• C. It has poor tarnish and corrosion resistance
• D. Mercury content in the final restoration is less

Explanation: High-copper amalgams generally have better resistance to tarnish and corrosion because the tin is tied up in copper-tin phases rather than…

• A. Require more mercury
• B. Require heavy compection forces
• C. Have longer setting times
• D. None of the above

Explanation: Spherical alloys usually need less mercury and less condensation force than conventional lathe-cut alloys, and they do not…

• A. Gamma 2
• B. Gamma 1
• C. Epsilon 1
• D. Gamma 3

Explanation: Gamma-2 is the weakest and most corrosion-prone phase of conventional amalgam, which is why high-copper alloys are designed to eliminate…

• A. 65% silver, 32% tin and 3% copper
• B. 49% silver, 32% tin and 19% cooper
• C. 65% silver, 29% tin and 5-6% copper
• D. None of the above

Explanation: The traditional ADA composition limits are approximately 65% silver, 29% tin and 5 to 6% copper, with small permissible variations.

• A. In the deepest part of the restoration
• B. In the centre of the restoration
• C. At the margin of the restoration
• D. None of the above

Explanation: Mercury concentration tends to be greatest near the margins, where condensation and adaptation can leave a more mercury-rich matrix.

• A. Mixing of amalgam alloy and mercury
• B. Lysing amalgam alloy
• C. Removal of excess of mercury
• D. None of the above

Explanation: Trituration is the mechanical mixing of amalgam alloy powder with mercury to produce a uniform amalgam mass.