Biomaterial Test

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Biomaterial Test

1 / 60

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

a. Light from an argon laser will activate polymerization.

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

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

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

2 / 60

Which of the following mixing methods permits the escape of dental amalgam mercury vapor ?

a. Mixing in a mortar and pestle

b. Proportioning mercury and alloy into a friction-fit capsule

c. Triturating precapsulated alloy and mercury

d. A cover over the mixing arms on a triturator

3 / 60

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

a. Cured for longer period

b. Not indicated

c. Fifth generation bonding agent should be applied

d. Restoration should be build in increments

4 / 60

Hand instruments for composites are made of 😕

a. Teflon-coated metal

b. Stainless steel

c. Carbon steel

d. Titanium

5 / 60

Setting time of alginate can be better controlled by 😕

a. Temperature of water used of mixing

b. Changing water: powder ratio

c. Mixing time

d. Chemical accelerators and retarders

6 / 60

Wrought metal 😕

a. Can be formed by working on a cast metal

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

c. Cannot be heat treated

d. Cannot be rendered corrosion resistant

7 / 60

Crystalline materials have 😕

a. No well-defined melting

b. Less stable space lattice

c. No space lattice

d. Well-defined melting

8 / 60

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

a. Floor carpeting

b. Baseboard heating

c. Amalgam scrap stored in a closed container

d. fluorite release

9 / 60

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

a. Porcelain

b. Gold alloy

c. Amalgam

d. Composite resin

10 / 60

The reason for hydroxyapatite coating on implant biomaterials is 😕

a. Greater bony opposition

b. Lesser bony apposition

c. Prolonged healing time

d. Presence of fibrous tissue

11 / 60

Metal has the following properties except 😕

a. Pure metals are not useful in dentistry

b. Metal is any element that ionizes positively in solution

c. Electroplated silver and copper are used in dies

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

12 / 60

Oxalates, carbonates, potassium, trisodium phosphates are added to alginate as 😕

a. Fillers

b. Retarders

c. Accelerators

d. Reactors

13 / 60

Impression plaster is a 😕

a. Mucostatic material

b. Thermoplastic material

c. Mucocompressive material

d. Reversible impression material

14 / 60

Which of the following properties of calcium hydroxide cement help in the formation of reparative dentin ?

a. High alkalinity

b. No Protein lysing effect

c. No antibacterial action

d. Low alkalinity

15 / 60

A full crown on a maxillary anterior tooth may be restored with which of the following restorative materials ?

a. Amalgam

b. Composite resin

c. Ceramic

d. Gold alloys

16 / 60

Polyether is different from other elastomers in the following aspects 😕

a. Low stiffness

b. Hydropholic in nature

c. High stiffiness

d. Can not be used as light cure material

17 / 60

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

a. Proportional limit

b. Percentage elongation

c. Flexibility

d. Yield strength

18 / 60

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

a. Cu-Sn

b. Ag-Hg

c. Sn-Hg

d. Ag-Sn

19 / 60

Binder in the phosphate investment is 😕

a. Magnesium oxide and monoammonium phosphate

b. Manganese dioxide

c. Cristobalite

d. Phosphoric acid

20 / 60

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

a. Gold alloy

b. Silver alloys

c. Ceramic

d. Amalgam

21 / 60

Calcium hydroxide is used for 😕

a. Reduce maginal leakage

b. Pulp capping

c. Reinforce the restoration

d. To prevent recurrent caries

22 / 60

Hypersensitivity reactions like contact dermatitis is caused by 😕

a. Polyether

b. Addition silicones

c. Condensation silicones

d. Polysulfides

23 / 60

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

a. All of them are a result of secondary reaction

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

c. All of them should be heated before using

d. All of them are polymers

24 / 60

Biting force in the molar region ranges from 😕

a. 400-890 N

b. 900-1000 N

c. 1000-1300 N

d. 600-1000 N

25 / 60

Nickel sensitivity in the general population is 😕

a. 11% for women

b. 1% in the overall population

c. 3% for men

d. 3% for women

26 / 60

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

a. Polyether

b. Polysulfide

c. Addition silicone

d. Condensation silicone

27 / 60

In dental porcelains metallic oxides provide 😕

a. Provides refractile property and increases strength

b. Color but decreases the strength

c. Color and increases the strength

d. Color and provides refractile property

28 / 60

Most commonly used pit and fissure sealant is 😕

a. Unfilled acrylic

b. Filled acrylic

c. Bis-GMA resin

d. Polyurethane

29 / 60

Setting of plaster of Paris is a result of 😕

a. Loss of water from hemihydrates

b. Indirect interaction between hemihydrates

c. Interaction between hemihydrates and water

d. Solubility difference between hemihydrates and dehydrate

30 / 60

Crystal structures of metals are all the following except 😕

a. Monoclinic

b. Tetragonal

c. Cubic

d. Circular

31 / 60

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

a. Increased solubility of the resin

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

c. Decreased polymerization of the resin

d. Subsequent oxidation of the tertiary amine

32 / 60

Silver has all the following characteristics except 😕

a. Silver in pure form is not used in dental restorations

b. Whitens when added to alloys

c. Silver points serve as a root canal filling material

d. Addition of palladium to silver increases corrosion

33 / 60

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

a. Gypsum

b. Water

c. Silica

d. Quartz

34 / 60

The light-cured restorative resins have advantages over chemically activated restorative resins as 😕

a. It is more sensitive to oxygen inhibitors

b. It has not more working time available

c. It has more working time available

d. It takes more time for curing

35 / 60

The impression material which is routinely used in auto mixing devicee system is 😕

a. Polyether

b. Condensation silicone

c. Polyvinyl siloxane

d. Polysulfied

36 / 60

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

a. Restorations are more brittle than low-copper versions

b. Better corrosion resistance than low-copper dental amalgams

c. Produce excessive creep

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

37 / 60

Minimal thickness of base for adequate thermal insulation is 😕

a. 1 mm

b. 0.75 mm

c. 2 mm

d. 0.5 mm

38 / 60

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

a. 100 ng Hg/m3 of air

b. All are corrects

c. 0.05 mg Hg/m3 of air

d. 30 ng Hg/m3 of air

39 / 60

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

a. Intramucosal frames

b. Endosseus implants

c. Subperiosteal

d. Transosteal frames

40 / 60

In a porcelain fused to metal restoration, when the coefficient of thermal expansion of metal and porcelain are different 😕

a. Porcelain will crack on cooling

b. Porcelain will not bond with metal

c. Porcelain will wear off

d. Porcelain will provide good shade

41 / 60

A potentially toxic element in base metal alloys is 😕

a. Molybdenum

b. Beryllium

c. Magnesium

d. Boron

42 / 60

The primary difference between low- and high-copper amalgams is which of the following ?

a. The amount of copper and silver

b. The amount of copper and zinc

c. The amount of copper

d. The amount of copper and tin

43 / 60

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

a. Type I

b. Type II

c. Type IV

d. Type III

44 / 60

Spot out incorrect statement regarding zinc in dentistry 😕

a. Pure zinc has no application in dentistry

b. It is relatively soft and ductile

c. It does not oxidize

d. It is low in strength

45 / 60

Most common use of Zinc oxide eugenol paste 😕

a. Wash impression for edentulous patients

b. Dual impression for Partially edentulous patients

c. As interocclusal record material

d. Surgical paste

46 / 60

Gypsum investments should not be heated above 😕

a. 4500C

b. 10000C

c. 7000C

d. 17000C

47 / 60

Of the four types of gold casting alloys, the most commonly used for crowns and bridges is 😕

a. Type II

b. Type I

c. Type IV

d. Type III

48 / 60

For proper wetting, contact angle should be ideally 😕

a. 00

b. 900

c. 600

d. 450

49 / 60

The following statements about dental porcelains are true except 😕

a. Undergoes discoloration

b. Crystalline nature

c. Undergoes firing shrinkage

d. It is brittle in nature

50 / 60

Bis-GMA is a reaction product of 😕

a. Bis-phenol-A and urethane dimethacrylate

b. Urethane dimethacrylate and glycidyl

c. Bis-phenol-A and methyl methacrylate

d. Bis-phenol-A and glycidyl methacrylate

51 / 60

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

a. Hardness

b. Toughness

c. Springiness

d. Brittleness

52 / 60

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

a. Sn-Hg

b. Cu-Sn

c. Ag-Su

d. Ag-Hg

53 / 60

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

a. Reduce firing shrinkage

b. Reduce brittleness

c. increase strength

d. Reduce porosity

54 / 60

Which of the following polymer systems are used for the organic matrix in composites ?

a. Poly (methyl methacrylate)

b. Polystyrene

c. Bisphenol A-glycidyl methacrylate (Bis-GMA)

d. Pheyl methacrylate

55 / 60

Softening of impressing compound is best accomplished by 😕

a. Oil bath

b. Water bath

c. Dry heat

d. Open flame

56 / 60

Porcelain-bonded to metal is stronger when fired 😕

a. Under compression

b. Several times in air

c. Under low temperature

d. After metal is tempered

57 / 60

Cavity varnish should not be applied when the following is used as a filling material 😕

a. Direct resin-filling material

b. Silicate

c. Amalgam

d. Zinc phosphate

58 / 60

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

a. Requires higher forces of condensation

b. Requires more mercury for trituration

c. Have longer setting time

d. Requires less amalgamation time

59 / 60

When the gold content of gold alloys increases 😕

a. The hardness decrease

b. Ductility decrease

c. The percentage elongation decrease

d. The corrosion resistance increases

60 / 60

The maximum warpage of acrylic denture occurs during 😕

a. Curing

b. Packing

c. Deflasking

d. Polishing

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