Biomaterial Test

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Biomaterial Test

1 / 60

The fluoride release from glass ionomer cement is 😕

a. 0.005 mg during the first week

b. 0.75 mg during the first week

c. 0.0005 mg during the first month

d. 0.075 mg during the first month

2 / 60

Clinical significance of smear layer :

a. Bonded to tooth structure and prevents composite adhesion

b. Improve the strength of the composite

c. Provides calcium for adhesion of composites

d. Increases the bonding action of the bonding agent

3 / 60

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

a. Floor carpeting

b. Baseboard heating

c. fluorite release

d. Amalgam scrap stored in a closed container

4 / 60

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

a. Has the toxic properties of unreacted mercury

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

c. Is combined primarily with silver

d. Composite restorative resins

5 / 60

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

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

b. Should be brittle

c. Should bond with dental porcelain

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

6 / 60

Porcelain denture teeth 😕

a. Have decreased abrasion resistance than dentin

b. Are easy to grind and polish

c. Are more resistant of abrasion than gold

d. Have higher coefficient of thermal expansion than resin teeth

7 / 60

Main disadvantage of denture base soft reliner is 😕

a. It can not lead to cleaned property

b. It can not lead to fungal growth

c. It can be cleaned properly

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

8 / 60

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

a. The amount of copper

b. The amount of copper and tin

c. The amount of copper and zinc

d. The amount of copper and silver

9 / 60

Which of the following statements about compomers are true ?

a. They typically are recommended for class II restorations.

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

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

d. They also are know as GIC

10 / 60

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

a. Carding wax

b. Utility wax

c. Base plate wax

d. Sticky wax

11 / 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

12 / 60

Gold with high percentage elongation is best for 😕

a. To improve the castability

b. To revert sagging during firing

c. To remove metallic oxide

d. Increase the bond strength

13 / 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. Restorations are more brittle than low-copper versions

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

d. Produce excessive creep

14 / 60

Nickel sensitivity in the general population is 😕

a. 3% for women

b. 3% for men

c. 1% in the overall population

d. 11% for women

15 / 60

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

a. Polyether

b. Polysulfide

c. Condensation silicone

d. Addition silicone

16 / 60

The reason zinc oxide eugenol cement is used as a temporary restoration 😕

a. It has an obtudant effect

b. It does not have anticariogenic activity

c. It does not form reparative dentin

d. It has poor tensile strength

17 / 60

Silver has all the following characteristics except 😕

a. Whitens when added to alloys

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

c. Silver points serve as a root canal filling material

d. Addition of palladium to silver increases corrosion

18 / 60

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

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

b. Results in a sharp decrease in flow

c. Results in a marked expansion

d. Increases the setting time

19 / 60

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

a. Polysulfides

b. Addition silicones

c. Polyethers

d. Condensation silicones

20 / 60

Ideal method firing of porcelain is by using 😕

a. Shorter firing at higher temperatures

b. Longer firing at high temperatures

c. Longer firing at low temperatures

d. Shorter firing at low temperatures

21 / 60

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

a. Conventional composites

b. Small particles

c. Hybrid composites

d. Microfilled composites

22 / 60

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

a. Adhesion

b. Flow

c. Dimensional stability

d. Biocompatibility

23 / 60

The following statements about dental porcelains are true except 😕

a. Crystalline nature

b. Undergoes discoloration

c. Undergoes firing shrinkage

d. It is brittle in nature

24 / 60

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

a. Quartz

b. Water

c. Gypsum

d. Silica

25 / 60

For luting purpose, the film thickness should be 😕

a. 25 μm or less

b. minimum 50 μm

c. up to 75 μm

d. ideally 100 μm

26 / 60

A potentially toxic element in base metal alloys is 😕

a. Molybdenum

b. Magnesium

c. Beryllium

d. Boron

27 / 60

Polyether is different from other elastomers in the following aspects 😕

a. High stiffiness

b. Can not be used as light cure material

c. Hydropholic in nature

d. Low stiffness

28 / 60

Softening of impressing compound is best accomplished by 😕

a. Water bath

b. Dry heat

c. Oil bath

d. Open flame

29 / 60

Passiveness of chrome cobalt alloys is due to formation of 😕

a. Chromium oxide

b. Cobalt oxide

c. Ferric oxide

d. Chromium carbide

30 / 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. Ease of casting

b. High strength

c. Thermal insulation

d. Esthetics

31 / 60

The energy absorbed by a material when it is stressed to its proportional limit is 😕

a. Flexibility

b. Resilience

c. Impact strength

d. Toughness

32 / 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. A cover over the mixing arms on a triturator

d. Mixing in a mortar and pestle

33 / 60

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

a. Acrylic resin

b. Composite restorative resins

c. Ceramic

d. Gold alloys

34 / 60

Spot out incorrect statement regarding zinc in dentistry 😕

a. It is low in strength

b. It does not oxidize

c. Pure zinc has no application in dentistry

d. It is relatively soft and ductile

35 / 60

Chemically cured resin shrinks:?

a. Towards the center of bulk of material

b. On the base only

c. On the surface only

d. Away from the light source

36 / 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

37 / 60

The most commonly employed alloy combination for use in implants is 😕

a. Titanium-platinum-aluminum alloy

b. Titanium-molybdenum-vanadium alloy

c. Titanium-aluminum-vanadium alloy

d. Platinum-aluminum-vanadium alloy

38 / 60

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

a. Ag-Hg

b. Sn-Hg

c. Cu-Sn

d. Ag-Sn

39 / 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. The bonding agent forms a hybrid layer with enamel.

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

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

40 / 60

Wrought metal 😕

a. Cannot be rendered corrosion resistant

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

c. Can be formed by working on a cast metal

d. Cannot be heat treated

41 / 60

In UV curing system the activator employed is 😕

a. Benzoin methyl ether

b. Dibutyl phthalate

c. Hydroquinone

d. Methyl methacrylate

42 / 60

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

a. Diketone-amine

b. Organic acid-peroxide

c. Organic acid-metal ion

d. Peroxide-amine

43 / 60

Most commonly used pit and fissure sealant is 😕

a. Filled acrylic

b. Unfilled acrylic

c. Bis-GMA resin

d. Polyurethane

44 / 60

Binder in the phosphate investment is 😕

a. Magnesium oxide and monoammonium phosphate

b. Manganese dioxide

c. Phosphoric acid

d. Cristobalite

45 / 60

Pick out the incorrect statement regarding alginate impressions 😕

a. Will be shrink as a result of syneresis

b. Will take up water and expand if kept wet

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

d. Is an irreversible hydrocolloid impression material

46 / 60

Resistance of a liquid to motion is called 😕

a. Creep

b. Viscosity

c. Springiness

d. Diffusion

47 / 60

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

a. Providing strength to the restoration

b. Saving the application of bonding agent

c. Compensating polymerization shrinkage

d. Achieving complete polymerization

48 / 60

Oil of clove is sometimes used in preference to eugenal in ZOE paste because :

a. Has a better reaction with zinc oxide

b. It increases mixing property of paste and therefore improves impression recorded

c. Reduces burning sensation of paste

d. To increase setting time

49 / 60

The main ingredient of casting waxes is 😕

a. Gum dammar

b. Carnauba wax

c. Paraffin wax

d. Candellila wax

50 / 60

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

a. 2:1

b. 1:2

c. 1:3

d. 3:1

51 / 60

Which of the following base is contraindicated for composites ?

a. Calcium hydroxide

b. Zinc oxide eugenol

c. Glass ionomer cement

d. Zinc phosphate

52 / 60

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

a. Does not alter setting time

b. Decreases setting time

c. Depends on rate of mixing

d. Increases setting time

53 / 60

Impression plaster is a 😕

a. Mucostatic material

b. Reversible impression material

c. Mucocompressive material

d. Thermoplastic material

54 / 60

The reason for hydroxyapatite coating on implant biomaterials is 😕

a. Presence of fibrous tissue

b. Lesser bony apposition

c. Greater bony opposition

d. Prolonged healing time

55 / 60

Gypsum investments should not be heated above 😕

a. 17000C

b. 7000C

c. 4500C

d. 10000C

56 / 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 of polyether consists of copolymer of ethylene oxide and tetrahydrofuran

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

57 / 60

Amalgam is less prone to corrosion 😕

a. If it contains 25-27% of tin

b. If it contains 4-6% of copper

c. If devoid of the gamma 2 phase

d. If it contains zinc

58 / 60

Which of the following occurs when dental amalgam is overmixed ?

a. Corrosion decreases

b. Corrosion increases

c. Compressive strength decreases

d. Tensile strength increases

59 / 60

Stearic acid in impression compound 😕

a. Increase setting time

b. Reduces flow

c. Reduces brittleness

d. Reduces plasticity

60 / 60

Higher mercury left in an amalgam leads to which of the following ?

a. Higher creep

b. High corrosion

c. Low corrosion

d. Higher strength

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