Free Properties of Dental Materials MCQs with Answers
87 Properties of Dental Materials MCQs from Dental Materials, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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- A. Yield strength
- B. Tensile strength
- C. Ultimate strength
- D. Proportional limit
Explanation: Yield strength is defined using a specified small permanent strain, commonly 0.2%, rather than complete fracture.
Correct answer: Yield strength- A. Elasticity of the test specimen in strain
- B. Area of the test specimen upon which the weight rests
- C. Length of the test specimen beneath the force
- D. Strain of the test specimen per unit length
Explanation: Stress is calculated as force divided by the cross-sectional area over which that force acts.
Correct answer: Area of the test specimen upon which the weight rests- A. An applied load or force
- B. A deformation resulting from an applied load
- C. An internal force opposing an applied load
- D. An external force opposing an applied load
Explanation: Stress is an internal resisting force developed within a material in response to an external load.
Correct answer: An internal force opposing an applied load- A. Unfilled acrylic plastics
- B. Zinc phosphate cements
- C. Porcelains
- D. Gold alloys
Explanation: Gold alloys are metals with closely packed atoms and therefore conduct heat much more efficiently than acrylic plastics, porcelains, or…
Correct answer: Gold alloys- A. Magnesium oxide & Phosphate
- B. Magnesium oxide & Monoammonium phosphate
- C. Magnesium oxide & Phosphoric acid
- D. Magnesium oxide & Ortho Phosphoric acid
Explanation: Phosphate-bonded investment uses magnesium oxide as the basic component and monoammonium phosphate as the acidic phosphate component…
Correct answer: Magnesium oxide & Monoammonium phosphate- A. Mineral
- B. Animal
- C. Insect
- D. Vegetable
Explanation: Dental waxes mainly come from mineral, vegetable, and insect sources, such as paraffin, carnauba, and beeswax.
Correct answer: Animal- A. To provide a smooth and glossy surface
- B. Increase toughness
- C. Decrease flow at room temperature
- D. Decrease toughness
Explanation: Carnauba is a hard, high-melting wax added to reduce the flow of dental wax at room or oral temperature and improve its rigidity.
Correct answer: Decrease flow at room temperature- A. Rockwell tester
- B. Barcol indenter
- C. Knoop pyramid
- D. Shore durometer
Explanation: Elastomer hardness is commonly measured with a Shore durometer, which uses an indenter to express the material’s resistance to…
Correct answer: Shore durometer- A. All of the above
- B. 2% potassium sulphate is accelerator
- C. Citrates are retarders
- D. Rapid spatulation results in decreased setting time
Explanation: Rapid spatulation increases the number of crystallisation nuclei and shortens setting time.
Correct answer: All of the above- A. Not waiting for 20 min before pouring
- B. All of the above
- C. Air incorporation in the mix
- D. High speed accelerator
Explanation: A rough or chalky cast surface may result from delayed pouring, a fast accelerator that causes premature surface setting, or air…
Correct answer: All of the above- A. Increased spatulation
- B. Less water powder ratio
- C. Adding potassium sulfate
- D. Allowing setting under water
Explanation: Potassium sulphate accelerates crystallisation but reduces the amount of setting expansion of gypsum.
Correct answer: Adding potassium sulfate- A. Citrales
- B. Nacl
- C. Na2 So4
- D. K2 So4
Explanation: Citrate salts, especially potassium or sodium citrate, are commonly used retarders for gypsum.
Correct answer: Citrales- A. Impression plaster
- B. Die stone
- C. Stone plaster
- D. Model plaster
Explanation: Die stone is formulated with a low setting expansion so that accurate dies can be produced.
Correct answer: Die stone- A. Testing the strength of plaster of paris
- B. Testing the metal hardness
- C. Evaluating the setting time of plaster of pris
- D. Testing the purity of noble metals
Explanation: A Gillmore needle determines the setting time of gypsum by testing when the material resists penetration.
Correct answer: Evaluating the setting time of plaster of pris- A. Reaction between hemihydrate and hihydrate
- B. Reaction between CaSO4+ 2H2O and water
- C. Nucleation and growth of CaSo4 ½ H2O crystals
- D. Difference in solubility of CaSo4 ½ H2O + CaSO4+ 2H2O
Explanation: Gypsum sets because the more soluble hemihydrate dissolves and the less soluble dihydrate precipitates as crystals.
Correct answer: Difference in solubility of CaSo4 ½ H2O + CaSO4+ 2H2O- A. Impression plaster
- B. Class I stone / Hydrocal
- C. Class II stone/Densite
- D. Model plaster
Explanation: Type I gypsum is impression plaster, used for making impressions of edentulous areas.
Correct answer: Impression plaster- A. Is wet calcined hemihydrate
- B. Has porous and irregular crystals
- C. Is a - hamihydrate
- D. Has a W / P of 0.2
Explanation: Plaster of Paris is usually the beta-hemihydrate, produced by dry calcination and characterised by porous, irregular particles.
Correct answer: Has porous and irregular crystals- A. 0.05
- B. 0.10
- C. 0.15
- D. 0.20
Explanation: ADA Specification No. 25 places the minimum setting expansion of Type V gypsum at 0.10%.
Correct answer: 0.10- A. Sharpe and size of particles
- B. Self life
- C. Chemical composition
- D. Solubility in water
Explanation: Dental plaster is made of more irregular, porous particles, whereas dental stone has denser, more regularly shaped particles produced by…
Correct answer: Sharpe and size of particles- A. Dry strength
- B. Green strength
- C. Water strength
- D. Compressive strength
Explanation: Green strength is the strength of a gypsum specimen while excess mixing water is still present.
Correct answer: Green strength