Biomaterial Test

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Biomaterial Test

1 / 60

The most accurate polysulfide impressions are made by using a custom acrylic tray because 😕

a. Custom tray made of plastic material ensures a uniform thickness of impression material

b. The tray does not distort during impression making

c. It can hold more amount of impression material

d. More pressure can be applied during impression making

2 / 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. Increased solubility of the resin

c. Decreased polymerization of the resin

d. Subsequent oxidation of the tertiary amine

3 / 60

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

a. Polysulfides

b. Condensation silicones

c. Polyether

d. Addition silicones

4 / 60

Calcium hydroxide is used for 😕

a. To prevent recurrent caries

b. Pulp capping

c. Reinforce the restoration

d. Reduce maginal leakage

5 / 60

Most commonly used pit and fissure sealant is 😕

a. Filled acrylic

b. Unfilled acrylic

c. Bis-GMA resin

d. Polyurethane

6 / 60

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

a. They cannot be soldered or welded

b. They can be heat treated

c. Their hardness is comparable to stainless steel

d. They have excellent tarnish and corrosion resistance

7 / 60

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

a. Carbide burs at high speed

b. Diamond burs at high speed

c. Diamond burs at low to medium speed

d. Carbide burs at low to medium speed

8 / 60

Adhesion in composites is due to 😕

a. Presence of smear layer

b. True chemical bonding to tooth structure

c. Cohesion

d. Mechanical interlocking

9 / 60

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

a. Glass ionomer cement

b. Silicate cement

c. Amalgam

d. Unfilled

10 / 60

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

a. Spermitic and bees wax

b. Paraffin and microcrystalline wax

c. Carnauba and candellia

d. Montan and Japan coco

11 / 60

Property which distinguishes composites from filled acrylic resins 😕

a. Adhesive bonding between matrix and filler

b. Bonding between coupling agent and filler

c. Bonding between coupling agent and tooth structure

d. Bonding with tooth structure

12 / 60

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

a. Type III

b. Type IV

c. Type I

d. Type II

13 / 60

Main disadvantage of laminate technique of making impression is : ?

a. Difficult to manipulate

b. Maximum details are not produced

c. Bond between agar and alginate is not very strong

d. Cost factor is high

14 / 60

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

a. Hybrid composites

b. Small particles

c. Microfilled composites

d. Conventional composites

15 / 60

Binder in the phosphate investment is 😕

a. Magnesium oxide and monoammonium phosphate

b. Cristobalite

c. Manganese dioxide

d. Phosphoric acid

16 / 60

Porcelain denture teeth 😕

a. Have higher coefficient of thermal expansion than resin teeth

b. Are easy to grind and polish

c. Have decreased abrasion resistance than dentin

d. Are more resistant of abrasion than gold

17 / 60

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

a. Gamma I Phase

b. Sulphide

c. Oxide

d. Gamma II Phase

18 / 60

The restorative material used to restore a small portion of an anterior tooth should have which of the following properties ?

a. Ease of casting

b. Esthetics

c. High strength

d. Amalgam

19 / 60

Which of the following materials are used for dental implants ?

a. Gold alloys

b. Cobalt and chromium alloys

c. Titanium

d. Metal alloys

20 / 60

Which of the following is the best choice of restorative material to achieve moderate to high strength, fluorite release, and esthetics ?

a. Compomer

b. Glass ionomer

c. Hybrid ionomer

d. Composite

21 / 60

In dental plaster the main ingredient is 😕

a. Calcium anhydrate

b. Calcium sulfate dehydrate

c. Calcium sulfate hemihydarate

d. Calcium phosphate

22 / 60

Wrought metal 😕

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

b. Cannot be heat treated

c. Can be formed by working on a cast metal

d. Cannot be rendered corrosion resistant

23 / 60

Dental porcelains are manufactured by a process termed as 😕

a. Fusing

b. Fritting

c. Sintering

d. Vulcanizing

24 / 60

Hypersensitivity reactions like contact dermatitis is caused by 😕

a. Polyether

b. Addition silicones

c. Condensation silicones

d. Polysulfides

25 / 60

Silver in the set amalgam alloy tends to have the following effect 😕

a. Produces contraction

b. Hydrolyzes the water if contaminated

c. Decreases ductility

d. Decreases the setting time

26 / 60

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

a. Latent heat

b. Fusion temperature

c. Temperature of vaporization

d. Specific temperature

27 / 60

Setting time of alginate can be better controlled by 😕

a. Mixing time

b. Chemical accelerators and retarders

c. Temperature of water used of mixing

d. Changing water: powder ratio

28 / 60

Dispensing composite resins using a syringe is advantageous because it 😕

a. Decreases air voids in the restoration

b. Increases surface smoothness

c. Increases strength and abrasive resistance

d. Conserves the material

29 / 60

Which of the following composites give rough surfaced finish ?

a. Small particle filled composites

b. Microfilled composites

c. Conventional composites

d. Hybrid composites

30 / 60

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

a. fluorite release

b. Floor carpeting

c. Baseboard heating

d. Amalgam scrap stored in a closed container

31 / 60

Proportional limit is defined as :

a. A deformation resulting from an applied load

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

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

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

32 / 60

Hydrocolloid impression should be removed from the mouth with a sharp jerk because 😕

a. It is the easiest method of removal

b. The brush heap structure of a gel responds more favorably to a sudden force

c. It decreases the time for syneresis to occur

d. Faster rate of removal increases the yield strength

33 / 60

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

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

b. All are correct

c. Microfilled

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

34 / 60

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

a. Hardness

b. Springiness

c. Toughness

d. Brittleness

35 / 60

Which of the following is used to alter contour of impression trays ?

a. Utility wax

b. Beading wax

c. Boxing wax

d. Carding wax

36 / 60

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

a. Gold alloy

b. Composite resin

c. Metal

d. Amalgam

37 / 60

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

a. Reduce brittleness

b. increase strength

c. Reduce porosity

d. Reduce firing shrinkage

38 / 60

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

a. Mixing in a mortar and pestle

b. A cover over the mixing arms on a triturator

c. Triturating precapsulated alloy and mercury

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

39 / 60

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

a. Organic acid-peroxide

b. Organic acid-metal ion

c. Peroxide-amine

d. Diketone-amine

40 / 60

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

a. Silica

b. Gypsum

c. Water

d. Quartz

41 / 60

Ideal method firing of porcelain is by using 😕

a. Longer firing at high temperatures

b. Longer firing at low temperatures

c. Shorter firing at low temperatures

d. Shorter firing at higher temperatures

42 / 60

The light from the visible light curing unit can cause 😕

a. Iritis

b. Cataract

c. Retinal damage

d. Corneal ulceration

43 / 60

The gelation temperature of agar hydrocolloid impression material should be 😕

a. 45-600C

b. 37-450C

c. Far below the oral temperature

d. 100C higher than mouth temperature

44 / 60

Crystal structures of metals are all the following except 😕

a. Cubic

b. Monoclinic

c. Tetragonal

d. Circular

45 / 60

Passiveness of chrome cobalt alloys is due to formation of 😕

a. Ferric oxide

b. Chromium carbide

c. Cobalt oxide

d. Chromium oxide

46 / 60

Chemically cured resin shrinks:?

a. On the surface only

b. On the base only

c. Towards the center of bulk of material

d. Away from the light source

47 / 60

Noble metal alloys are classified according to their 😕

a. Melting temperature

b. Castability

c. Malleability

d. Dental function

48 / 60

Which of the following statements about laboratory composites are true ?

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

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

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

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

49 / 60

Following are the functions of impression compound except 😕

a. To make impression of edentulous ridge

b. To make individual die impression with copper band

c. To record mucostatic impressions

d. To make special tray for final impression

50 / 60

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

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

b. Light from an argon laser will activate 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.

51 / 60

The chemistry behind the condensation of the amalgam is to 😕

a. Condense the unattacked gamma II particles

b. To reduce gamma II particules

c. Condense the unattacked gamma particles

d. Condense the unattacked gamma I particles

52 / 60

When a mechanical device is used for mixing addition silicones 😕

a. Mixing time is reduced

b. There is no greater uniformity in proportioning and mixing

c. Mixing time is long

d. More possibilities of contamination

53 / 60

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

a. Addition silicone

b. Polysulfide

c. Polyether

d. Condensation silicone

54 / 60

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

a. Saving the application of bonding agent

b. Providing strength to the restoration

c. Achieving complete polymerization

d. Compensating polymerization shrinkage

55 / 60

A potentially toxic element in base metal alloys is 😕

a. Molybdenum

b. Beryllium

c. Magnesium

d. Boron

56 / 60

Glass ionomer cenment is not recommended for 😕

a. Class IV resoration

b. Class I restoration

c. Class V restoration

d. Class III restoration

57 / 60

Polyether is different from other elastomers in the following aspects 😕

a. High stiffiness

b. Low stiffness

c. Hydropholic in nature

d. Can not be used as light cure material

58 / 60

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

a. It has an obtudant effect

b. It does not form reparative dentin

c. It has poor tensile strength

d. It does not have anticariogenic activity

59 / 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

60 / 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 also are know as GIC

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

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