Dental Materials Mcqs - Set 2

1)   Which of the following is NOT true of polymethyl methacrylate ?

a. Knoop hardness number 18 to 20
b. Tensile strength of 60 MPa
c. Density of 1.13 g/cm3
d. Modulus of elasticity of 3.4 GPa
Answer  Explanation 

ANSWER: Modulus of elasticity of 3.4 GPa

Explanation:
No explanation is available for this question!


2)   Etchant preferred in gel from than in liquid form________________?

a. Better control over placement
b. Enhance and concentrate the action of acid
c. Helps in visualization while placement
d. None of the above
Answer  Explanation 

ANSWER: Better control over placement

Explanation:
No explanation is available for this question!


3)   During polymerisation of acrylic resin, above what temperature benzoyl peroxide form freeradicals_______________?

a. 25°C
b. 37°C
c. 50°C
d. 60°C
Answer  Explanation 

ANSWER: 60°C

Explanation:
No explanation is available for this question!


4)   Etching depth after 30 sec for orthodontic bracket with orthophosphoric acid is_________________?

a. 10 um – 20 um
b. 3 um – 9 um
c. 50 um – 110 um
d. 200 um – 250 um
Answer  Explanation 

ANSWER: 10 um – 20 um

Explanation:
No explanation is available for this question!


5)   The accepted polymer to monomer ratio for packing of polymethyl methacrylate resin is____________?

a. 3:1
b. 4:1
c. 10:1
d. 5:1
Answer  Explanation 

ANSWER: 3:1

Explanation:
No explanation is available for this question!


6)   Residual monomer content of chemically activated resins is______________?

a. 0.2% to 0.5%
b. 2% to 5%
c. 0.3% to 0.5%
d. 2% to 5%
Answer  Explanation 

ANSWER: 2% to 5%

Explanation:
No explanation is available for this question!


7)   Dentin conditioner has the following function______________?

a. Removes smear layer
b. Increases surface energy of dentin
c. Forms a thin resin layer over exposed collagen fibrils
d. Helps in bonding with composite
Answer  Explanation 

ANSWER: Removes smear layer

Explanation:
No explanation is available for this question!


8)   The process wherein two or more chemically different monomers, each with some desirable property, can be combined to yield specific physical properties of a polymer is known as_____________?

a. Step-growth polymerization
b. Addition polymerization
c. Condensation polymerization
d. Copolymerization
Answer  Explanation 

ANSWER: Copolymerization

Explanation:
No explanation is available for this question!


9)   Denture acrylics contain cross-linking agents mainly to improve their_____________?

a. Internal color
b. Tissue compability
c. Surface hardness
d. Craze resistance
Answer  Explanation 

ANSWER: Craze resistance

Explanation:
No explanation is available for this question!


10)   Subsurface porosity is due to_____________?

a. Thermal changes
b. Thickness of the resin
c. Lack of temperature
d. Packing past the dough stage
Answer  Explanation 

ANSWER: Thermal changes

Explanation:
No explanation is available for this question!


11)   If resin is packed in sandy stage what will be seen in the processed denture ?

a. Distortion
b. Porosity
c. Inhomogeneous colour
d. Increased strength
Answer  Explanation 

ANSWER: Porosity

Explanation:
No explanation is available for this question!


12)   Which one of the following is used as filler in composite resins ?

a. Quartz
b. Silicates
c. Zinc particles
d. Aluminium
Answer  Explanation 

ANSWER: Quartz

Explanation:
No explanation is available for this question!


13)   Insufficient closure of the flasks during packing of denture base resin can result in_____________?

a. Poor colour stability
b. Less polymerization shrinkage
c. Increase in vertical dimension
d. Decrease in vertical dimension
Answer  Explanation 

ANSWER: Increase in vertical dimension

Explanation:
No explanation is available for this question!


14)   Quartz tungsten light cure device minimum output of energy should not be less than_____________?

a. 300 mw/sm2
b. 350 mw/cm2
c. 400 mw/cm2
d. 450 mw/cm2
Answer  Explanation 

ANSWER: 300 mw/sm2

Explanation:
No explanation is available for this question!


15)   Polymerisation of heat-cured methyl methacrylate is initiated by______________?

a. Tertiary amine
b. Benzoyl peroxide free radical
c. Hydroquinone
d. Methyl ether
Answer  Explanation 

ANSWER: Benzoyl peroxide free radical

Explanation:
No explanation is available for this question!


16)   In processing methyl methacrylate, the resin may show porosity if the flask is placed too soon porosity most likely occur_____________?

a. Throughout the denture
b. Near the borders
c. In the thickest part
d. On the denture surface
Answer  Explanation 

ANSWER: In the thickest part

Explanation:
No explanation is available for this question!


17)   Composite resins in comparison to acrylic have_______________?

a. Low compressive strength
b. High abrasive resistance
c. High water absorption
d. High polymerization shrinkage
Answer  Explanation 

ANSWER: High abrasive resistance

Explanation:
No explanation is available for this question!


18)   The chemical used to etch enamel is_______________?

a. Zinc oxide
b. Methyl methacrylate
c. Phosphoric acid
d. Eugenol
Answer  Explanation 

ANSWER: Phosphoric acid

Explanation:
No explanation is available for this question!


19)   Which of the following procedure is indicated to produce cross-linking in the polymerization of linear chains of acrylic_______________?

a. Addition of grain refining agents
b. Addition of difunctional monomers
c. Increasing the amount of heat required for linear polymerization
d. Incorporation of terminating agents
Answer  Explanation 

ANSWER: Addition of difunctional monomers

Explanation:
No explanation is available for this question!


20)   For photo-curing the composite resin the light source______________?

a. Should be held at a millimeter distance from the restoration
b. Need no protection while in use
c. Will cure composite upto a depth of 5 millimeter thickness
d. Is fiber optic
Answer  Explanation 

ANSWER: Should be held at a millimeter distance from the restoration

Explanation:
No explanation is available for this question!


21)   In self-cure acrylic resin, activator is_____________?

a. Toluidine
b. Quaternary ammonium compound
c. Benzoyl peroxide
d. Tertiary amine
Answer  Explanation 

ANSWER: Tertiary amine

Explanation:
No explanation is available for this question!


22)   Marginal leakage related to temperature change occurs to the greatest extent with_______________?

a. Amalgam alloy
b. Unfilled resin
c. Composite resin
d. Direct filling gold
Answer  Explanation 

ANSWER: Unfilled resin

Explanation:
No explanation is available for this question!


23)   Acrylic resins were first introduced as a denture base material in______________?

a. 1925
b. 1937
c. 1951
d. 1956
Answer  Explanation 

ANSWER: 1937

Explanation:
No explanation is available for this question!


24)   What is the disadvantage of using composites as restorative material ?

a. Increased thermal conductivity
b. Decreased wear resistance
c. Decreased thermal conductivity
d. None of the above
Answer  Explanation 

ANSWER: Decreased wear resistance

Explanation:
No explanation is available for this question!


25)   The % of free monomer in a heat – cured acrylic resin is_______________?

a. 3% to 5%
b. 8% to 10%
c. 0.2% to 0.5%
d. 0.6% to 0.8%
Answer  Explanation 

ANSWER: 0.2% to 0.5%

Explanation:
No explanation is available for this question!


26)   Inadequate pressure application during flasking_______________?

a. Increases vertical dimension
b. Causes teeth to be shrunken in investment
c. Causes poor quality of colour
d. Causes fracture of denture
Answer  Explanation 

ANSWER: Increases vertical dimension

Explanation:
No explanation is available for this question!


27)   Inorganic phase of the composites aid in_______________?

a. Increasing the mechanical strength
b. Decreasing the coefficient of thermal expansion
c. Reducing the polymerization shrinkage
d. All of the above
Answer  Explanation 

ANSWER: All of the above

Explanation:
No explanation is available for this question!


28)   About polymerization shrinkage of composite all are true, except______________?

a. Polymerization shrinkage is greater if bonded surface area is lesser than unbounded surface area
b. Polymerization shrinkage is high if within the enamel margins
c. Acid etching and priming will decrease polymerization shrinkage
d. Microleakage can occur because of polymerization shrinkage
Answer  Explanation 

ANSWER: Polymerization shrinkage is greater if bonded surface area is lesser than unbounded surface area

Explanation:
No explanation is available for this question!


29)   The advantage of unfilled methyl methacrylate is that______________?

a. It can be finished smoothly
b. It has a low degree of flow
c. It’s non-irritation to pulp
d. It’s wear resistant is high
Answer  Explanation 

ANSWER: It can be finished smoothly

Explanation:
No explanation is available for this question!


30)   Dentin bonding agents usually contain_____________?

a. Only Hydrophobic component
b. Only Hydrophilic component
c. Hydrophobic and hydrophilic component
d. Lyophillic and lyophobic component
Answer  Explanation 

ANSWER: Hydrophobic and hydrophilic component

Explanation:
No explanation is available for this question!


31)   Which of the following provide opacity to composite ?

a. TEGDMA
b. BIS-GMA
c. Ti02
d. None of the above
Answer  Explanation 

ANSWER: Ti02

Explanation:
No explanation is available for this question!


32)   The polymerization of self-curing resin takes faster in______________?

a. Cold water
b. Hot water
c. Under pressure
d. In vaccum
Answer  Explanation 

ANSWER: Hot water

Explanation:
No explanation is available for this question!


33)   Acid-etching is done for_______________?

a. 30 seconds
b. 60 seconds
c. 90 seconds
d. 120 seconds
Answer  Explanation 

ANSWER: 30 seconds

Explanation:
No explanation is available for this question!


34)   No trail closure is necessary with which one of the technique during denture fabrication_____________?

a. Compression moulding technique
b. Injection moulding technique
c. Fluid resin technique
d. Light cured technique
Answer  Explanation 

ANSWER: Injection moulding technique

Explanation:
No explanation is available for this question!


35)   The function of the coupling agent in a restorative resin is to allow______________?

a. Adhesion of resin particles
b. Bonding between filler crystals
c. Bonding between filler and resin
d. Bonding between tooth and resin
Answer  Explanation 

ANSWER: Bonding between tooth and resin

Explanation:
No explanation is available for this question!


36)   Which of the following constituents is common in occlusal sealants, bonding agents, composite resins ?

a. BIS GMA
b. Polymethyl methacrylate
c. Benzoin methyl ether
d. Silica filter
Answer  Explanation 

ANSWER: BIS GMA

Explanation:
No explanation is available for this question!


37)   The most important disadvantage of acrylic denture base is_______________?

a. porosity
b. Shrinkage
c. Tooth breakage
d. Water absorption
Answer  Explanation 

ANSWER: Shrinkage

Explanation:
No explanation is available for this question!


38)   Radio opacity to composite resins is rendered by_______________?

a. Silica glass
b. Organic matrix
c. Barium glass and strontium glasses
d. Fluoride particles
Answer  Explanation 

ANSWER: Barium glass and strontium glasses

Explanation:
No explanation is available for this question!


39)   Acrylic (cold cure)______________?

a. Melts at 100°C
b. Softens at 100°C
c. Still requires heat for polymerization
d. Produces heat during polymerization
Answer  Explanation 

ANSWER: Produces heat during polymerization

Explanation:
No explanation is available for this question!


40)   Use of dimethyl-P-toluidine is indicated for_______________?

a. Thermal polymerization of acrylic
b. Chemical polymerization
c. Retarding the polymerization reaction
d. To inhibit the action of benzoyl peroxide
Answer  Explanation 

ANSWER: Chemical polymerization

Explanation:
No explanation is available for this question!