Biomaterial Test

5 votes, 5 avg

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Biomaterial Test

1 / 60

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

a. Oxide

b. Sulphide

c. Gamma II Phase

d. Gamma I Phase

2 / 60

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

a. 4 mm

b. 2 mm

c. 3 mm

d. 1 mm

3 / 60

In a porcelain fused to metal restoration, the porcelain is-bonded to metal by 😕

a. Chemical bonding

b. Chemico-mechenical bonding

c. High malleafility of metal

d. Hight ductility of metal

4 / 60

Greater ratio fo zinc oxide to eugenol will have the following effect on setting time 😕

a. Increases setting time

b. Depends on rate of mixing

c. Decreases setting time

d. Does not alter setting time

5 / 60

Bis-GMA is a reaction product of 😕

a. Bis-phenol-A and glycidyl methacrylate

b. Urethane dimethacrylate and glycidyl

c. Bis-phenol-A and urethane dimethacrylate

d. Bis-phenol-A and methyl methacrylate

6 / 60

One of the disadvantages of using quartz as filler in restorative resin is 😕

a. It cannot be polished

b. It cause abrasion and wearing of opposing tooth surface

c. It cannot be reduced to the size of microparticle composite

d. It has low affinity for resin matrix

7 / 60

The light from the visible light curing unit can cause 😕

a. Cataract

b. Iritis

c. Retinal damage

d. Corneal ulceration

8 / 60

Setting of plaster of Paris is a result of 😕

a. Loss of water from hemihydrates

b. Indirect interaction between hemihydrates

c. Solubility difference between hemihydrates and dehydrate

d. Interaction between hemihydrates and water

9 / 60

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

a. Yield strength, tensile strength, toughness

b. Elastic limit, yield strength, proportional limit

c. Elastic limit, modulus of elasticity, tensile strength

d. Toughness, rigidity, resilience

10 / 60

Proconditioning before GIC restoration is done in order to 😕

a. Create tags

b. Facilitate mechanical bonding

c. Provide more strenght

d. Remove smear layer

11 / 60

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

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

b. Triturating precapsulated alloy and mercury

c. Mixing in a mortar and pestle

d. A cover over the mixing arms on a triturator

12 / 60

The cracks formed on the ceramic during cooling because 😕

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

b. The outer layer cools more rapidly than the interior

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

d. Due to external forces

13 / 60

Which of the following statements about adhesion of composite restorations to tooth structure are true ?

a. Most bonding agent bond more effectively to a dry tooth surface.

b. Bonding is achieved to enamel by application of an acid etchant followed by application of a bonding agent and then the composites resin.

c. The bonding agent forms a hybrid layer with enamel.

d. The bonding agent forms a micromechanical bond with enamel but a chemical bond with dentin.

14 / 60

The most effective cement in stimulating tertiary dentin is 😕

a. Zinc silicophoshpate

b. Zinc phosphate

c. Calcum hydroxide

d. Polycardoxylate

15 / 60

Setting time of alginate can be better controlled by 😕

a. Chemical accelerators and retarders

b. Temperature of water used of mixing

c. Changing water: powder ratio

d. Mixing time

16 / 60

Property which distinguishes composites from filled acrylic resins 😕

a. Adhesive bonding between matrix and filler

b. Bonding between coupling agent and tooth structure

c. Bonding between coupling agent and filler

d. Bonding with tooth structure

17 / 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

18 / 60

Which of the following materials are used for dental implants ?

a. Cobalt and chromium alloys

b. Metal alloys

c. Gold alloys

d. Titanium

19 / 60

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

a. Endosseus implants

b. Subperiosteal

c. Transosteal frames

d. Intramucosal frames

20 / 60

The purpose of burnishing the amalgam after condensation is to 😕

a. To reduce gamma II particule

b. Reduce surface microporosities

c. To prevent recurrent carries

d. To reduce discoloration

21 / 60

The chemistry behind the condensation of the amalgam is to 😕

a. To reduce gamma II particules

b. Condense the unattacked gamma I particles

c. Condense the unattacked gamma II particles

d. Condense the unattacked gamma particles

22 / 60

Materials having coefficient of thermal expansion close to the tooth structure 😕

a. Glass ionomer cement

b. Unfilled

c. Silicate cement

d. Amalgam

23 / 60

The fluoride release from glass ionomer cement is 😕

a. 0.005 mg during the first week

b. 0.075 mg during the first month

c. 0.75 mg during the first week

d. 0.0005 mg during the first month

24 / 60

Softening of impressing compound is best accomplished by 😕

a. Dry heat

b. Oil bath

c. Open flame

d. Water bath

25 / 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

26 / 60

Resistance of a liquid to motion is called 😕

a. Viscosity

b. Creep

c. Springiness

d. Diffusion

27 / 60

Proportional limit is defined as :

a. A deformation resulting from an applied load

b. The maximum force required to cause a structure to break

c. The stress/strain ratio within the elastic limit in a structure

d. The maximum stress that can be induced without permanent deformation

28 / 60

A potentially toxic element in base metal alloys is 😕

a. Beryllium

b. Molybdenum

c. Boron

d. Magnesium

29 / 60

Which of the following waxes used to align of castings before soldering ?

a. Utility wax

b. Sticky wax

c. Carding wax

d. Base plate wax

30 / 60

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

a. Reduce brittleness

b. Reduce firing shrinkage

c. Reduce porosity

d. increase strength

31 / 60

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

a. Triturating precapsulated alloy and mercury

b. A cover over the mixing arms on a triturator

c. Mixing in a mortar and pestle

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

32 / 60

Which of the following is called periphery wax ?

a. Beading wax

b. Sticky wax

c. Bite registration wax

d. Utility wax

33 / 60

Potato starch is contained in which impression material ?

a. Agar agar

b. Potassium sulfate

c. Impression plaster

d. Impression compound

34 / 60

For proper wetting, contact angle should be ideally 😕

a. 600

b. 00

c. 900

d. 450

35 / 60

Sulfur contamination from natural latex gloves inhibits the setting of 😕

a. Polyether

b. Alginate

c. Zinc oxide eugenol impression paste

d. Polyvinyl siloxane

36 / 60

Which of the following uses a hardened steel ball indenting tool ?

a. Rockwell hardness test

b. Brinell hardness test

c. Vichers hardness test

d. Knoop hardness test

37 / 60

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

a. Modulus of elasticity

b. Flexibility

c. Toughness

d. Resilience

38 / 60

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

a. Cu-Sn

b. Sn-Hg

c. Ag-Sn

d. Ag-Hg

39 / 60

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

a. Polysulfides

b. Addition silicones

c. Condensation silicones

d. Polyethers

40 / 60

Ideal metal used for electroplating polysulfide impression is 😕

a. Cobalt

b. Silver

c. Copper

d. Nickel

41 / 60

Greening effect of porcelain is due to 😕

a. Silver

b. Golde

c. Palladium

d. Platinum

42 / 60

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

a. Peroxide-amine

b. Diketone-amine

c. Organic acid-peroxide

d. Organic acid-metal ion

43 / 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.

44 / 60

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

a. Ag-Su

b. Ag-Hg

c. Cu-Sn

d. Sn-Hg

45 / 60

Which of the following composite is recommended for non stress bearing anterior restoration ?

a. Hybrid composites

b. Microfilled composites

c. Small particles

d. Conventional composites

46 / 60

Ideally, the set amalgam should do which of the following ?

a. Have little dimensional change

b. Properties of amalgam

c. Shrink significantly to provide space for correction products to seal the margins

d. Expand greatly to provide marginal seal against the tooth

47 / 60

Which of the following material has a high coefficient of thermal expansion ?

a. Composite resin

b. Silicate cement

c. Glass ionomer cement

d. Unfilled acrylic resin

48 / 60

Light source in the curing unit is usually 😕

a. Infra red bulb

b. Tungsten halogen light bulb

c. Sun light

d. Ultraviolet light bulb

49 / 60

In UV curing system the activator employed is 😕

a. Benzoin methyl ether

b. Dibutyl phthalate

c. Hydroquinone

d. Methyl methacrylate

50 / 60

For each property, list the amalgam type (irregular low-copper, admixed high-copper, and spherical high-copper ) that has the highest value?.

a. Creep irregular low-copper

b. Tensile strength spherical high-copper

c. 1-hour compressive strength spherical high-copper

d. Creep irregular high-copper

51 / 60

Noble metal alloys are classified according to their 😕

a. Castability

b. Malleability

c. Dental function

d. Melting temperature

52 / 60

Montan waxes have the following properties except 😕

a. Have low melting points of 42oC

b. Obtained by extraction from lignite

c. Hard, brittle and lustrous

d. Are mineral waxes

53 / 60

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

a. Carbone steal

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

c. Artificial waxes teeth are attached

d. They are attached to natural teeth with cements,

54 / 60

One of the following statements which one is incorrect regarding polyether :

a. The base paste consists of polyether polymer

b. Aromatic sulfonate ester acts as a cross linking agent

c. The main chain consists of copolymer of methylene oxide and tetrahydrofuran

d. The main chain of polyether consists of copolymer of ethylene oxide and tetrahydrofuran

55 / 60

Elgiloy arch wire is 😕

a. Optical fiber arch wire

b. Gold alloy

c. β-titanium arch wire

d. Cobalt-chromium-nickel alloy

56 / 60

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

a. Amalgam scrap stored in a closed container

b. Baseboard heating

c. Wall carpeting

d. Floor carpeting

57 / 60

For luting purpose, the film thickness should be 😕

a. ideally 100 μm

b. up to 75 μm

c. minimum 50 μm

d. 25 μm or less

58 / 60

Chemically cured resin shrinks:?

a. On the surface only

b. Towards the center of bulk of material

c. Away from the light source

d. On the base only

59 / 60

A direct restorative material used frequently to restore a portion of a posterior tooth that is subject to large biting forces would possess which of the following properties ?

a. Thermal insulation

b. Ease of casting

c. Esthetics

d. High strength

60 / 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 more working time available

c. It takes more time for curing

d. It has not more working time available

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