Biomaterial Test

5 votes, 5 avg

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Biomaterial Test

1 / 60

The appropriate proportion of polymer to monomer component of dental resin by volume is generally 😕

a. 1:2

b. 1:3

c. 2:1

d. 3:1

2 / 60

The maximum warpage of acrylic denture occurs during 😕

a. Curing

b. Deflasking

c. Packing

d. Polishing

3 / 60

Which of the following statements is true regarding zinc phosphate cement ?

a. Is used as a permanent restorative material in adults

b. Is the oldest luting agent

c. The least irritant to the pulp

d. Has an obtudant effect on the pulp

4 / 60

In dental porcelains metallic oxides provide 😕

a. Color and provides refractile property

b. Color but decreases the strength

c. Color and increases the strength

d. Provides refractile property and increases strength

5 / 60

Contamination of zinc-containing amalgam by moisture during triturating or condensation :

a. Results in a sharp decrease in flow

b. Results in a marked expansion

c. Increases the setting time

d. Has no appreciable effect on properties except to the susceptibility to tarnish

6 / 60

Amalgam is less prone to corrosion 😕

a. If it contains 4-6% of copper

b. If devoid of the gamma 2 phase

c. If it contains zinc

d. If it contains 25-27% of tin

7 / 60

The cracks formed on the ceramic during cooling because 😕

a. The outer layer cools more rapidly than the interior

b. The cooling of the outer and the inner layer occurs at the same rate

c. Due to external forces

d. The inner layer cools more rapidly than the outer layer

8 / 60

The light from the visible light curing unit can cause 😕

a. Corneal ulceration

b. Iritis

c. Retinal damage

d. Cataract

9 / 60

Once amalgamation has occurred, which of the following is true of mercury ?

a. Can form at the surface of amalgam restorations if heated to 0° C

b. Has the toxic properties of unreacted mercury

c. Is combined primarily with silver

d. Composite restorative resins

10 / 60

Working time of denture resin should be at least 😕

a. 5 minutes

b. 10 minutes

c. 20 minutes

d. 15 minutes

11 / 60

Which of the following composites give rough surfaced finish ?

a. Small particle filled composites

b. Conventional composites

c. Microfilled composites

d. Hybrid composites

12 / 60

The common characteristic for pit and fissure sealant composite resins, acrylic appliances and elastomeric impression materials is :

a. All of them can be employed as anterior filling materials

b. All of them are polymers

c. All of them should be heated before using

d. All of them are a result of secondary reaction

13 / 60

Adhesion in composites is due to 😕

a. Presence of smear layer

b. Mechanical interlocking

c. Cohesion

d. True chemical bonding to tooth structure

14 / 60

Cobalt-chromium alloy is mostly used for the construction of 😕

a. Subperiosteal

b. Endosseus implants

c. Transosteal frames

d. Intramucosal frames

15 / 60

Minimum light exposure time for composite resins should be 😕

a. 20 sec

b. 5 sec

c. 40 sec

d. 10 sec

16 / 60

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

a. Resilience

b. Flexibility

c. Toughness

d. Modulus of elasticity

17 / 60

The chemistry behind the condensation of the amalgam is to 😕

a. Condense the unattacked gamma I particles

b. Condense the unattacked gamma particles

c. Condense the unattacked gamma II particles

d. To reduce gamma II particules

18 / 60

Polyether is different from other elastomers in the following aspects 😕

a. Low stiffness

b. Can not be used as light cure material

c. High stiffiness

d. Hydropholic in nature

19 / 60

Which of the following statements apply to the packable composites ?

a. Their wear rate is low (3.5 μm/year). Which is similar to that of amalgam.

b. Radiopaque

c. They are radiolucent.

d. Their depth of cure allows bulk polymerization, which has been shown to be clinically effective.

20 / 60

Which of the following elastomers is suited for multiple cast pouring 😕

a. Polysulfide

b. Condensation silicone

c. Polyether

d. Addition silicone

21 / 60

Ideal method firing of porcelain is by using 😕

a. Longer firing at high temperatures

b. Shorter firing at higher temperatures

c. Longer firing at low temperatures

d. Shorter firing at low temperatures

22 / 60

Thickness of the gel between the tray and tissue for either agar or alginate should always be at least 😕

a. 1 mm

b. 3 mm

c. 4 mm

d. 2 mm

23 / 60

The product that is formed on the surface of the amalgam restoration and frequently result in discoloration is 😕

a. Gamma II Phase

b. Sulphide

c. Gamma I Phase

d. Oxide

24 / 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

25 / 60

Hypersensitivity reactions like contact dermatitis is caused by 😕

a. Addition silicones

b. Polyether

c. Polysulfides

d. Condensation silicones

26 / 60

Which of the following sentences describes the construction of removable partial dentures ?

a. Artificial waxes teeth are attached

b. They are attached to natural teeth with cements,

c. Carbone steal

d. They are removable and attached to teeth with clasps.

27 / 60

A portion of a posterior tooth that is subject to high biting forces would likely be restored with which of the following ?

a. Acrylic resin

b. Amalgam

c. Composite resin

d. Glass ionomer

28 / 60

Which of the following initiator-accelerator systems is needed for a light-activated composite?

a. Organic acid-peroxide

b. Peroxide-amine

c. Organic acid-metal ion

d. Diketone-amine

29 / 60

Wet porcelain is condensed properly before firing to enhance all the properties except : ?

a. Reduce porosity

b. Reduce brittleness

c. increase strength

d. Reduce firing shrinkage

30 / 60

The desirable quality of porcelain is 😕

a. Requirement of color

b. Thermal expansion

c. Toughness without brittleness

d. Translucency

31 / 60

Which of these statements apply to the filler particles of composites ?

a. Microfilled composites contain more filler than all-purpose composites.

b. Microhybrid composites contain as much as 84% filler by weight.

c. Microfilled

d. All are correct

32 / 60

Minimal thickness of base for adequate thermal insulation is 😕

a. 0.75 mm

b. 2 mm

c. 0.5 mm

d. 1 mm

33 / 60

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

a. Polysulfide

b. Polyether

c. Condensation silicone

d. Addition silicone

34 / 60

Gold casting alloys are classified as type I, II, III or IV among these, having highest hardness is 😕

a. Type III

b. Type II

c. Type I

d. Type IV

35 / 60

Pick out the incorrect statement regarding alginate impressions 😕

a. Will be shrink as a result of syneresis

b. Is an irreversible hydrocolloid impression material

c. May exhibit a fluid exudates on the surface as a result of imbibitions

d. Will take up water and expand if kept wet

36 / 60

Dispensing composite resins using a syringe is advantageous because it 😕

a. Increases strength and abrasive resistance

b. Increases surface smoothness

c. Decreases air voids in the restoration

d. Conserves the material

37 / 60

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

a. Flexibility

b. Proportional limit

c. Percentage elongation

d. Yield strength

38 / 60

Wrought metal 😕

a. Can be formed by working on a cast metal

b. Cannot be heat treated

c. Cannot be rendered corrosion resistant

d. Can be formed by pouring molten metal into a mold

39 / 60

Commonly used coloring agent in impression plaster is 😕

a. Congo red

b. Alizarin red

c. Indigo dye

d. Metallic oxide

40 / 60

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

a. Carbide burs at low to medium speed

b. Diamond burs at low to medium speed

c. Carbide burs at high speed

d. Diamond burs at high speed

41 / 60

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

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

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

c. Light from an argon laser will activate polymerization.

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

42 / 60

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

a. They cannot be soldered or welded

b. They have excellent tarnish and corrosion resistance

c. They can be heat treated

d. Their hardness is comparable to stainless steel

43 / 60

If the light cure resin is curd in increments, it helps in 😕

a. Achieving complete polymerization

b. Providing strength to the restoration

c. Compensating polymerization shrinkage

d. Saving the application of bonding agent

44 / 60

Stiffness of the material with passage of time is maximum in 😕

a. Condensation silicones

b. Polysulfides

c. Addition silicones

d. Polyether

45 / 60

The constituent that acts as a binder in the investment is 😕

a. Gypsum

b. Water

c. Quartz

d. Silica

46 / 60

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

a. Marginal ditching along occlusal margins

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

c. Micrographs of alloys particles.

d. Wear facets along the occlusal contach areas

47 / 60

Which of the following office conditions minimize the health hazard from spilled mercury ?

a. Amalgam scrap stored in a closed container

b. Floor carpeting

c. Baseboard heating

d. Wall carpeting

48 / 60

The main advantage of composites compared to silicates cement is 😕

a. Color matching with the tooth structure is excellent

b. High modulus of resilience

c. Practically insoluble in oral fluids

d. Coefficient of thermal expansion close to tooth structure

49 / 60

All are properties of waxes except 😕

a. Creep

b. Flow

c. Solidification shrinkage

d. Plastic deformation

50 / 60

Elgiloy arch wire is 😕

a. Gold alloy

b. β-titanium arch wire

c. Cobalt-chromium-nickel alloy

d. Optical fiber arch wire

51 / 60

Color stability of cold-cured resins is inferior to that of heat cured resins due to 😕

a. Variation in the molecular weight of the resin (low mol wt)

b. Decreased polymerization of the resin

c. Increased solubility of the resin

d. Subsequent oxidation of the tertiary amine

52 / 60

Which of the following occurs when dental amalgam is overmixed ?

a. Tensile strength increases

b. Compressive strength decreases

c. Corrosion decreases

d. Corrosion increases

53 / 60

Full denture bases are usually made from which of the following materials ?

a. Ceramic

b. Composite restorative resins

c. Acrylic resin

d. Gold alloys

54 / 60

Hand instruments for composites are made of 😕

a. Carbon steel

b. Titanium

c. Teflon-coated metal

d. Stainless steel

55 / 60

The following statements about dental porcelains are true except 😕

a. Undergoes firing shrinkage

b. Crystalline nature

c. It is brittle in nature

d. Undergoes discoloration

56 / 60

In dental plaster the main ingredient is 😕

a. Calcium sulfate hemihydarate

b. Calcium sulfate dehydrate

c. Calcium anhydrate

d. Calcium phosphate

57 / 60

Condensation of porcelain is done by all the methods except 😕

a. Ceramming method

b. Vibration method

c. Brush addition technique

d. Spatulation method

58 / 60

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

a. Ceramic

b. Silver alloys

c. Amalgam

d. Gold alloy

59 / 60

Thermal conductivity is proportional to 😕

a. Type of metal

b. Hardness of metal

c. Area of conduction

d. Fusion temperature

60 / 60

Conventional dental amalgam alloy contains 😕

a. Silver, mercury, copper and mercury

b. Silver, tin, copper and zinc

c. Silver, tin, palladium and zinc

d. Silver, mercury, copper and zinc

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