Biomaterial Test

5 votes, 5 avg

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Biomaterial Test

1 / 60

Setting time of alginate can be better controlled by 😕

a. Chemical accelerators and retarders

b. Changing water: powder ratio

c. Temperature of water used of mixing

d. Mixing time

2 / 60

Ideal method firing of porcelain is by using 😕

a. Shorter firing at higher temperatures

b. Longer firing at low temperatures

c. Shorter firing at low temperatures

d. Longer firing at high temperatures

3 / 60

A cavity varnish used for lining the preparation for a dental amalgam restoration will :

a. Reduce early marginal leakage tooth structure

b. Provide strength of amalgam

c. Provide electrical insulation

d. Provide thermal insulation

4 / 60

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

a. Increased solubility of the resin

b. Decreased polymerization of the resin

c. Subsequent oxidation of the tertiary amine

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

5 / 60

Crystalline materials have 😕

a. Less stable space lattice

b. No space lattice

c. Well-defined melting

d. No well-defined melting

6 / 60

KHN of enamel is 😕

a. 300

b. 100

c. 90-100

d. 600

7 / 60

Dispensing composite resins using a syringe is advantageous because it 😕

a. Increases surface smoothness

b. Conserves the material

c. Decreases air voids in the restoration

d. Increases strength and abrasive resistance

8 / 60

Hypersensitivity reactions like contact dermatitis is caused by 😕

a. Condensation silicones

b. Polysulfides

c. Polyether

d. Addition silicones

9 / 60

Which of the following waxes is obtained from distillation of petroleum ?

a. Paraffin and microcrystalline wax

b. Carnauba and candellia

c. Spermitic and bees wax

d. Montan and Japan coco

10 / 60

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

a. Gold

b. Waxe

c. Ceramic

d. Glass ionomer

11 / 60

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

a. Quartz

b. Silica

c. Gypsum

d. Water

12 / 60

Spot out incorrect statement regarding zinc in dentistry 😕

a. It does not oxidize

b. Pure zinc has no application in dentistry

c. It is relatively soft and ductile

d. It is low in strength

13 / 60

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

a. Carbide burs at high speed

b. Carbide burs at low to medium speed

c. Diamond burs at high speed

d. Diamond burs at low to medium speed

14 / 60

The desirable quality of porcelain is 😕

a. Toughness without brittleness

b. Thermal expansion

c. Translucency

d. Requirement of color

15 / 60

Which of the following properties would be of least importance, when selecting an impression material ?

a. Biocompatibility

b. Dimensional stability

c. Flow

d. Adhesion

16 / 60

Following are the functions of impression compound except 😕

a. To record mucostatic impressions

b. To make impression of edentulous ridge

c. To make special tray for final impression

d. To make individual die impression with copper band

17 / 60

Which one of the following is not true about high-copper dental amalgam restorations ?

a. Better corrosion resistance than low-copper dental amalgams

b. Produce excessive creep

c. Restorations are more brittle than low-copper versions

d. Contain both Sn and Ag in the composition as well

18 / 60

In dental porcelains metallic oxides provide 😕

a. Color but decreases the strength

b. Color and increases the strength

c. Color and provides refractile property

d. Provides refractile property and increases strength

19 / 60

Most commonly used pit and fissure sealant is 😕

a. Bis-GMA resin

b. Polyurethane

c. Unfilled acrylic

d. Filled acrylic

20 / 60

The chemistry behind the condensation of the amalgam is to 😕

a. Condense the unattacked gamma particles

b. To reduce gamma II particules

c. Condense the unattacked gamma II particles

d. Condense the unattacked gamma I particles

21 / 60

Chemically cured resin shrinks:?

a. On the base only

b. Away from the light source

c. Towards the center of bulk of material

d. On the surface only

22 / 60

Which of the following occurs when dental amalgam is overmixed ?

a. Tensile strength increases

b. Corrosion decreases

c. Corrosion increases

d. Compressive strength decreases

23 / 60

Main disadvantage of laminate technique of making impression is : ?

a. Difficult to manipulate

b. Bond between agar and alginate is not very strong

c. Cost factor is high

d. Maximum details are not produced

24 / 60

Carnauba wax is preferred to candelilla wax as 😕

a. It is sticky

b. It has low melting temperature

c. It is harder and has less flow

d. It provides luster to the pattern

25 / 60

Resistance of a liquid to motion is called 😕

a. Creep

b. Viscosity

c. Springiness

d. Diffusion

26 / 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. 0.05 mg Hg/m3 of air

b. 0.04 mg Hg/m3 of air

c. 30 mg Hg/m3 of air

d. 100 mg Hg/m3 of air

27 / 60

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

a. Ag-Su

b. Cu-Sn

c. Sn-Hg

d. Ag-Hg

28 / 60

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

a. They are attached to natural teeth with cements,

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

c. Carbone steal

d. Artificial waxes teeth are attached

29 / 60

Which of the following statements apply to the packable composites ?

a. They are radiolucent.

b. Radiopaque

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

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

30 / 60

Which of the following statements about laboratory composites are true ?

a. Restorations prepared from laboratory composites typically are cemented with zinc phosphate cement.

b. Fiber reinforcement increases their strength but decrease their rigidity.

c. Curing using light, heat, and pressure increase the wear resistance.

d. Bridge prepared from laboratory composites require a metal substructure.

31 / 60

The gelation temperature of agar hydrocolloid impression material should be 😕

a. Far below the oral temperature

b. 100C higher than mouth temperature

c. 45-600C

d. 37-450C

32 / 60

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

a. They cannot be soldered or welded

b. Their hardness is comparable to stainless steel

c. They have excellent tarnish and corrosion resistance

d. They can be heat treated

33 / 60

The physical property measured in terms of the deformation of the structure per until dimensions is ?

a. Stress

b. Space lattice

c. Strain

d. Amorphous material

34 / 60

Wrought metal 😕

a. Cannot be heat treated

b. Can be formed by working on a cast metal

c. Cannot be rendered corrosion resistant

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

35 / 60

A small portion of an anterior tooth would most likely be restored with which of the following ?

a. Gold alloy

b. Composite resin

c. Porcelain

d. Amalgam

36 / 60

Glass ionomer cenment is not recommended for 😕

a. Class I restoration

b. Class IV resoration

c. Class V restoration

d. Class III restoration

37 / 60

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

a. Brittleness

b. Hardness

c. Springiness

d. Toughness

38 / 60

In an alloy oxygen scavenger is 😕

a. Zinc

b. Copper

c. Silver

d. Palladium

39 / 60

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

a. Polyether

b. Addition silicone

c. Condensation silicone

d. Polysulfide

40 / 60

Metal has the following properties except 😕

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

b. Electroplated silver and copper are used in dies

c. Pure metals are not useful in dentistry

d. Metal is any element that ionizes positively in solution

41 / 60

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

a. Requires more mercury for trituration

b. Have longer setting time

c. Requires less amalgamation time

d. Requires higher forces of condensation

42 / 60

Crystal structures of metals are all the following except 😕

a. Tetragonal

b. Monoclinic

c. Cubic

d. Circular

43 / 60

Main disadvantage of denture base soft reliner is 😕

a. It can not lead to cleaned property

b. It can be cleaned properly

c. It can not lead to fungal growth

d. It has not to be changed over a period of time

44 / 60

Light source in the curing unit is usually 😕

a. Sun light

b. Tungsten halogen light bulb

c. Infra red bulb

d. Ultraviolet light bulb

45 / 60

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

a. Temperature of specificity

b. Vapor temperature

c. Heat temperature

d. Fusion temperature

46 / 60

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

a. Type II

b. Type III

c. Type IV

d. Type I

47 / 60

Amalgam is less prone to corrosion 😕

a. If it contains zinc

b. If it contains 25-27% of tin

c. If devoid of the gamma 2 phase

d. If it contains 4-6% of copper

48 / 60

A potentially toxic element in base metal alloys is 😕

a. Beryllium

b. Boron

c. Magnesium

d. Molybdenum

49 / 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. Composite resin

c. Amalgam

d. Glass ionomer

50 / 60

The main advantage of composites compared to silicates cement is 😕

a. Coefficient of thermal expansion close to tooth structure

b. High modulus of resilience

c. Practically insoluble in oral fluids

d. Color matching with the tooth structure is excellent

51 / 60

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

a. Polyethers

b. Addition silicones

c. Condensation silicones

d. Polysulfides

52 / 60

Setting of plaster of Paris is a result of 😕

a. Interaction between hemihydrates and water

b. Indirect interaction between hemihydrates

c. Loss of water from hemihydrates

d. Solubility difference between hemihydrates and dehydrate

53 / 60

Pick out the incorrect statement regarding alginate impressions 😕

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

b. Will be shrink as a result of syneresis

c. Will take up water and expand if kept wet

d. Is an irreversible hydrocolloid impression material

54 / 60

Commonly used coloring agent in impression plaster is 😕

a. Metallic oxide

b. Indigo dye

c. Alizarin red

d. Congo red

55 / 60

Conventional dental amalgam alloy contains 😕

a. Silver, tin, palladium and zinc

b. Silver, mercury, copper and zinc

c. Silver, tin, copper and zinc

d. Silver, mercury, copper and mercury

56 / 60

Which of the following is recommended as an adhesive to trays with polysulfides ?

a. Styrene-acrylonitrile

b. Polydimethyl siloxane

c. Acrylic resin

d. Ethyl silicate

57 / 60

Gypsum investments should not be heated above 😕

a. 10000C

b. 17000C

c. 7000C

d. 4500C

58 / 60

The temperature at which a solid changes into liquid is called 😕

a. Fusion temperature

b. Temperature of vaporization

c. Specific temperature

d. Latent heat

59 / 60

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

a. Should bond with dental porcelain

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

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

d. Should be brittle

60 / 60

Minimal thickness of base for adequate thermal insulation is 😕

a. 0.75 mm

b. 0.5 mm

c. 1 mm

d. 2 mm

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