Biomaterial Test

5 votes, 5 avg

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Biomaterial Test

1 / 60

Which of the following statements about compomers are true ?

a. They are two-paste systems that self-cure within 2 to 3 minutes.

b. They also are know as GIC

c. They typically are recommended for class II restorations.

d. Because of their resin content, they require a bonding agent for adhesion to tooth structure.

2 / 60

A measure of ductility of a material is referred to as 😕

a. Percentage elongation

b. Flexibility

c. Proportional limit

d. Yield strength

3 / 60

Proconditioning before GIC restoration is done in order to 😕

a. Provide more strenght

b. Facilitate mechanical bonding

c. Create tags

d. Remove smear layer

4 / 60

Which one of the following represents the maximum safe concentration of mercury vapor in the breathing zone for a 40-hour work week ?

a. 30 mg Hg/m3 of air

b. 100 mg Hg/m3 of air

c. 0.04 mg Hg/m3 of air

d. 0.05 mg Hg/m3 of air

5 / 60

Porcelain denture teeth 😕

a. Have higher coefficient of thermal expansion than resin teeth

b. Have decreased abrasion resistance than dentin

c. Are more resistant of abrasion than gold

d. Are easy to grind and polish

6 / 60

Excess composite from the labial surfaces can be removed by using 😕

a. Carbide burs at high speed

b. Diamond burs at high speed

c. Diamond burs at low to medium speed

d. Carbide burs at low to medium speed

7 / 60

Porcelain-bonded to metal is stronger when fired 😕

a. Several times in air

b. Under compression

c. Under low temperature

d. After metal is tempered

8 / 60

The most effective cement in stimulating tertiary dentin is 😕

a. Polycardoxylate

b. Zinc phosphate

c. Calcum hydroxide

d. Zinc silicophoshpate

9 / 60

Which one of the following is not a criterion for a failed high-copper dental amalgam restorations ?

a. Creep of the restoration out of the cavity preparation in proximal areas

b. Micrographs of alloys particles.

c. Marginal ditching along occlusal margins

d. Wear facets along the occlusal contach areas

10 / 60

Which of the following components acts as a refractory material in porcelain ?

a. Potash

b. Feldspar

c. Silica

d. Kaolin

11 / 60

Which one of the following phases in dental amalgam restoration is most prone to electrochemical corrosion ?

a. Sn-Hg

b. Cu-Sn

c. Ag-Su

d. Ag-Hg

12 / 60

In dental porcelains metallic oxides provide 😕

a. Color and provides refractile property

b. Provides refractile property and increases strength

c. Color but decreases the strength

d. Color and increases the strength

13 / 60

Which of the following is a measure of resistance to fracture ?

a. Toughness

b. Hardness

c. Brittleness

d. Springiness

14 / 60

Glass ionomer cenment is not recommended for 😕

a. Class I restoration

b. Class V restoration

c. Class III restoration

d. Class IV resoration

15 / 60

The strain at which the plastic strain develops may be represented by 😕

a. Elastic limit, yield strength, proportional limit

b. Elastic limit, modulus of elasticity, tensile strength

c. Yield strength, tensile strength, toughness

d. Toughness, rigidity, resilience

16 / 60

The most commonly used implant type presently is 😕

a. Transosteal implant

b. Endosseous

c. Subperiosteal

d. Intramucosal implant

17 / 60

All of the following are properties of Co-Cr-Ni wires except 😕

a. Their hardness is comparable to stainless steel

b. They cannot be soldered or welded

c. They can be heat treated

d. They have excellent tarnish and corrosion resistance

18 / 60

In deep caities, the resin which remains unpolymerized can cause 😕

a. Porosity in restoration

b. Sagging of restoration

c. Pulp inflammation

d. Secondary caries

19 / 60

Dispensing composite resins using a syringe is advantageous because it 😕

a. Increases surface smoothness

b. Decreases air voids in the restoration

c. Conserves the material

d. Increases strength and abrasive resistance

20 / 60

Setting of plaster of Paris is a result of 😕

a. Indirect interaction between hemihydrates

b. Solubility difference between hemihydrates and dehydrate

c. Loss of water from hemihydrates

d. Interaction between hemihydrates and water

21 / 60

Which has the highest viscoelastic property and requires more time to recover from deformation ?

a. Polyether

b. Addition silicone

c. Polysulfide

d. Condensation silicone

22 / 60

Working time of denture resin should be at least 😕

a. 5 minutes

b. 20 minutes

c. 15 minutes

d. 10 minutes

23 / 60

Minimal thickness of base for adequate thermal insulation is 😕

a. 1 mm

b. 0.75 mm

c. 2 mm

d. 0.5 mm

24 / 60

Zinc oxide eugenal impression should be removed from oral cavity :

a. When the material is glossy

b. When it can be easily indented by a blunt instrument

c. Exactly after four minutes after kneading

d. When the material cannot be intended by a blunt instrument

25 / 60

Acrylic resins are used in which of the following ?

a. Denture bases

b. Ceramic ( porcelain )-fused-to-metal crowns

c. Posterior inlays

d. Anterior onlays

26 / 60

Montan waxes have the following properties except 😕

a. Hard, brittle and lustrous

b. Have low melting points of 42oC

c. Obtained by extraction from lignite

d. Are mineral waxes

27 / 60

The noble or base metal alloys used for PFM should have the following requisite :

a. Should be brittle

b. Coefficient of thermal expansion should not be compatible with porcelain

c. Its melting temperature should be low in comparison with firing temperature of porcelain

d. Should bond with dental porcelain

28 / 60

Ideal method firing of porcelain is by using 😕

a. Shorter firing at low temperatures

b. Longer firing at high temperatures

c. Longer firing at low temperatures

d. Shorter firing at higher temperatures

29 / 60

Porosity in denture base resins can be due to 😕

a. Well flasking of wax pattern

b. Adequate mixing of liquid and powder components

c. Applying sufficient pressure during polymerization

d. Excess heating of resin above its boiling point

30 / 60

In visible light-cured composites photo initiator molecule is 😕

a. Benzoyl methyl ether

b. Toluidine

c. Camphoroquinone

d. Bis-phenol-A

31 / 60

Alginate impression material deteriorates rapidly at 😕

a. Low temperature

b. Temperature does not cause any change in shelf-life

c. Normal room temperature

d. Elevated temperature

32 / 60

Binder in the phosphate investment is 😕

a. Magnesium oxide and monoammonium phosphate

b. Cristobalite

c. Manganese dioxide

d. Phosphoric acid

33 / 60

Which of the following is the best choice of restorative material to achieve moderate to high strength, fluorite release, and esthetics ?

a. Compomer

b. Glass ionomer

c. Composite

d. Hybrid ionomer

34 / 60

Which one of the following phases in dental amalgam restoration has the best mechanical properties ?

a. Cu-Sn

b. Ag-Hg

c. Sn-Hg

d. Ag-Su

35 / 60

Strain that occurs when the material is stressed to its proportional limit is called 😕

a. Modulus of elasticity

b. Resilience

c. Flexibility

d. Toughness

36 / 60

Distortion on removal from undercuts in addition silicones is very less due to 😕

a. Increased strain rate on unset material

b. Shrinkage of material

c. Lowest strain in compression

d. Stiffness of the material

37 / 60

Strength of dental porcelain is dependent on 😕

a. Rough

b. Resistance to fusion

c. No internal structure

d. Composition

38 / 60

The temperature at which a solid changes to liquid is known as its 😕

a. Fusion temperature

b. Vapor temperature

c. Heat temperature

d. Temperature of specificity

39 / 60

Minimum light exposure time for composite resins should be 😕

a. 20 sec

b. 10 sec

c. 40 sec

d. 5 sec

40 / 60

Which of the following occurs when dental amalgam is overmixed ?

a. Compressive strength decreases

b. Corrosion decreases

c. Corrosion increases

d. Tensile strength increases

41 / 60

Commonly used filler in composite is 😕

a. Glass

b. Quartz

c. Colloidal silica

d. Aluminum

42 / 60

Passiveness of chrome cobalt alloys is due to formation of 😕

a. Ferric oxide

b. Chromium oxide

c. Chromium carbide

d. Cobalt oxide

43 / 60

Elgiloy arch wire is 😕

a. Optical fiber arch wire

b. β-titanium arch wire

c. Cobalt-chromium-nickel alloy

d. Gold alloy

44 / 60

Which of the following statements about curing of composites are true ?

a. Exposure times of 2 to 3 seconds are needed for polymerization with visible light.

b. Before light activation, the base and catalyst pastes are mixed.

c. Lights with both blue and red wavelengths are equally effective for polymerization.

d. Light from an argon laser will activate polymerization.

45 / 60

Hypersensitivity reactions like contact dermatitis is caused by 😕

a. Addition silicones

b. Condensation silicones

c. Polyether

d. Polysulfides

46 / 60

The greatest amount of dimensional change after setting is exhibited by 😕

a. Condensation silicones

b. Polysulfides

c. Polyethers

d. Addition silicones

47 / 60

The main function of zinc in amalgam is 😕

a. To increase the longevity of amalgam after setting

b. To increase the shelf-life of an amalgam

c. To produce delayed expansion

d. To prevent the creep

48 / 60

In the cavities which are more than 2mm deep a light-cured restoration is 😕

a. Not indicated

b. Restoration should be build in increments

c. Fifth generation bonding agent should be applied

d. Cured for longer period

49 / 60

All are properties of waxes except 😕

a. Flow

b. Solidification shrinkage

c. Creep

d. Plastic deformation

50 / 60

An anterior fixed partial denture could have facings constructed of which of the following materials ?

a. Amalgam

b. Ceramic

c. Gold alloy

d. Silver alloys

51 / 60

Setting time of alginate can be better controlled by 😕

a. Changing water: powder ratio

b. Mixing time

c. Temperature of water used of mixing

d. Chemical accelerators and retarders

52 / 60

Hydrocolloid impression should be removed from the mouth with a sharp jerk because 😕

a. It is the easiest method of removal

b. It decreases the time for syneresis to occur

c. The brush heap structure of a gel responds more favorably to a sudden force

d. Faster rate of removal increases the yield strength

53 / 60

Which of the following metals currently are used in dental alloys ?

a. Gold

b. Glass ionomer

c. Ceramic

d. Waxe

54 / 60

Adhesion in composites is due to 😕

a. Presence of smear layer

b. Cohesion

c. True chemical bonding to tooth structure

d. Mechanical interlocking

55 / 60

Which of the following properties are higher for microhybrid composites than for microfilled composites ?

a. Thermal expansion

b. Water sorption

c. Polymerization shrinkage

d. Modulus of elasticity

56 / 60

Silver in the set amalgam alloy tends to have the following effect 😕

a. Decreases the setting time

b. Decreases ductility

c. Produces contraction

d. Hydrolyzes the water if contaminated

57 / 60

Sulfur contamination from natural latex gloves inhibits the setting of 😕

a. Polyether

b. Polyvinyl siloxane

c. Zinc oxide eugenol impression paste

d. Alginate

58 / 60

Metal has the following properties except 😕

a. Metal is any element that ionizes positively in solution

b. Pure metals are not useful in dentistry

c. Electroplated silver and copper are used in dies

d. All metals do not have same degrees of strength and plasticity

59 / 60

Compared to lathe-cut alloy, spherical dental amalgam alloys 😕

a. Requires less amalgamation time

b. Have longer setting time

c. Requires more mercury for trituration

d. Requires higher forces of condensation

60 / 60

Spot out incorrect statement regarding zinc in dentistry 😕

a. It does not oxidize

b. It is relatively soft and ductile

c. Pure zinc has no application in dentistry

d. It is low in strength

Your score is

The average score is 86%

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