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Sample > Final 2013 > Flashcards

Final 2013 Flashcards

1
Q
  1. Which of the following is the best description of a solid solution?
    a. the creation of an alloy by pressure and heat forming a biphasic solid structure
    b. two metals combined such that one element is in some grains and the second element is in the other grains
    c. the random distribution of the atoms of one element within the lattice Structure of a second element in the solid state
    d. two immiscible metallic elements forming a eutectic
    e. the arrangement of the atoms of one element at specific intervals and geometries in the lattice structure of a second element in the solid state
A

c. the random distribution of the atoms of one element within the lattice structure of a second element in the solid state

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2
Q

Which of the following Bravais lattice structures is the closest packing arrangement?

a. face centered cubic
b. orthorhombic
c. body centered cubic
d. tetragonal - martensitic
e. simple cubic

A

a. face centered cubic

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3
Q

The largest particle sim that may be considered nanosized is about 200 nanometers.
What is another way of identifing that measurement?
a. 0.2 millimeters
b. 20 angstroms
c. 2 angstroms
d. 0.2 micrometers
e. 2,000 micrometers

A

d. 0.2 micrometers

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4
Q

What is a possible short term consequence of microleakage?

a. decreased bond strength
b. post-operative sensitivity
c. pulpal necrosis
d. fracture of the restoration
e. poor esthetic match of the material to the tooth

A

b. post-operative sensitivity

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5
Q

What does the term shelf life indicate?

a. How long the material can be used in the office to make a filling material
b. How long the restoration will last in the mouth
c. The prognosis of the filling material when placed in a laboratory artificial tooth
d. The beginning of a change in the esthetics Of the material when sitting on the shelf
e. The period of time before the liquid component of a material can sit on the shelf before it completely evaporates

A

a. How long the material can be used in the office to make a filling material

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6
Q

Which of the following is a result of refractive index mismatch in a composite restorative material between a glass filler and its resin matrix?

a. the composite has more flexibility
b. the composite has more water sorption
c. the composite is more transparent
d. the composite is more brittle
e. material is more opaque

A

e. material is more opaque

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7
Q

Which color system is used to calculate the amount change in color Of an esthetic restorative material when exposed to staining agents?

a. Munsell
b. Mosaic
c. additive mixing
d. L*,a*,b*
e. Ostwald

A

d. L*,a*,b*

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8
Q

What are the three regions designated On all diagrams for every metallic element?

a. stress, strain, modulus of elasticity
b. liquid, liquid/solid combination, solid
c. solid solution, interrnetallic compound, amorphous
d. assivation, active corrosion
e. occlusal, facial, gingival

A

d. assivation, active corrosion

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9
Q

Which of the following is a metal or alloy that passivates in normal oral conditions?

a. alumina
b. silica
c. iron-carbide
d. gold-palladium-copper
e. chromium

A

e. chromium

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10
Q

In laboratory studies of accelerated corrosion, the accelerated rate of corrosion is produced by what, which is the independent variable?

a. The total force per unit cross-sectional area.
b. The electromotive force integrated over time.
c. The current per unit surface area.
d. The voltage applied.
e. change in current resulting from cyclical mechanical force application.

A

d. The voltage applied.

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11
Q

What is oral galvanism?
a. pulpal pathosis leading to pulpal necrosis
b. a systemic toxicity resulting from the absorption of the ions of metals in dental restorations
c the change in occlusal relationships due to metal restorations
d. a current in the mouth due to different metallic restorations possible causing pulpal pain
e. inducing gingival hyperplasia due to metal margins on crowns

A

d. a current in the mouth due to different metallic restorations possible causing pulpal pain

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12
Q

Which of the following is not one of the four mechanisms that increase corrosion of an alloy?

a. Heterogeneous composition
b. Inhomogeneous surface
c. Two different metals in the mouth
d. Pits
e. Integrative resistance

A

e. Integrative resistance

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13
Q

What is strain in mechanical property testing?

a. the internal force per unit cross-sectional area of a material when an external force is applied
b. the force at which a material fails
c. the dimensional change at failure
d. the force per deformation that takes place inside a material e. the change in dimension of a solid material in response to an external force divided by the original dimension

A

e. the change in dimension of a solid material in response to an external force divided by the original dimension

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14
Q

What is a limitation on using diametral tensile testing to determine the tensile strength of a material?

a. The material must be viscoelastic.
b. The unset material must be available in large quantities.
c. The material must be tough
d. The set material must be wider at the ends than it is in the middle.
e. The set material must have a high modulus of elasticity.

A

e. The set material must have a high modulus of elasticity.

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15
Q

What kind of mechanical test is creep?

a. The measurement Of the loss of material through wear
b. determination of the ultimate strength by means of fatigue cycling
c. The measurement of the change in dimension by application of a constant load lower than its ultimate strength
d. The measurement of the change in the stress material exhibits under a constant strain
e. The determination of the proportional limit by means of a constantly increasing load and the offset that allows easy reading of an intersection with a parallel line to the initial slope

A

c. The measurement of the change in dimension by application of a constant load lower than its ultimate strength

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16
Q

Which of the following is the best laboratory test for predicting clinical failure by fracture ?

a. compressive strength
b. fracture toughness
c. shear strength
d. fatigue testing
e. flexural strength

A

d. fatigue testing

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17
Q

What is viscoelasticity?

a. the description of a fluid that is sticky
b. the description of a material that does not follow a normal stress strain curve because of its elastic and fluid properties
c. the description of the mechanical properties of fluid
d. the description of the mechanical properties of a rigid solid
e. the description of a solid material that still has a liquid, or molten, component within the matrix of the grain or crystalline structure

A

b. the description of a material that does not follow a normal stress strain curve because of its elastic and fluid properties

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18
Q

For the crown and bridge material represented by line at what stress will the material fail because the bridge starts to deform permanently?

a. 500 MPa
b. 400 MPa
c. 0.05
d. 0.11
e. 0.10

A

b. 400 MPa

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19
Q

Which line represents a material with the highest modulus of elasticity?

a. A
b. B
c. C
d. D
e. E

A

a. A

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20
Q

Which line represents a material with the greatest toughness?

a. A
b. B
c. C
d. D
e. E

A

c. C

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21
Q

Which of the following means that the toxic effects are felt in the offspring and not in the individual exposed?

a. allergenicity
b. mutagenicity
c. teratogenicity
d. carcinogenicity
e. chronic toxicity

A

c. teratogenicity

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22
Q

Which of the following is the best description of an exposure to a toxic material?

a. the negative effect on a biological system
b. the inhalation of a material that may be toxic
c. the distribution of a chemical agent through the body
d. being in the presence Of a toxin that is encased in a hermetically sealed container
c. risk involved when contacting a new matcrial

A

b. the inhalation of a material that may be toxic

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23
Q

Which of the following are the two factors to be considered when determining the risk while performning a risk analysis on a material or chemical?

a. information on the web and the benefit of the material or chemical
b. the incidence of the adverse effect and the perception Of the population
c. the benefit of the material or chemical and the seriousness Of the negative effect
d. the severity of the adverse effect and the percent of the population that could be affected
e. the governmental regulations and the relative benefit of the material

A

d. the severity of the adverse effect and the percent of the population that could be affected

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24
Q

What FDA product classification does most Of Our dental materials qualify under?

a. Class I
b. Class II
c. Class III
d. Class IV
e. Class V

A

b. Class II

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25
Q

What is the organization that creates the standards for dental materials and devices for sale that are produced in the United States and whether the dental device can be exported?

a. SCDP
b. CE
c. NIST
d. FDA
e. ISO

A

a. SCDP

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26
Q

What is the organization that creates standards for all kinds of materials for many nations throughout the world and thus influences the final form of the standards that are accepted within the United States?

a. SCDP
b. CE
c. NIST
d. FDA
e. ISO

A

e. ISO

27
Q

Which of the following “phases of steel” is used for cutting blades on dental hand instruments and scalpel blades that can be the hardest steel?

a. austenitic
b. hardenistic
c. tungsten-carbide
d. ferritic
e. martinsitic

A

e. martinsitic

28
Q

Which Of the following is not a way for hardening a metal?

a. forming carbide precipitates in the alloy grain structure
b. annealing
c. grain refinement
d. cold working
e. alloying the metal with another element

A

b. annealing

29
Q

Which of the following does increasing carbon content do when in very small concentrations in nickel-chromium alloys?

a. increases the strength by forming carbide precipitates
b. decreases the strength by forming a solid solution
c. increases the corrosion resistance by helping to form an oxide layer
d. increases the corrosion resistance by forming an iron-carbide coating
e. increases both corrosion resistance and strength by providing a stronger lining to the grain structure even at the surface

A

a. increases the strength by forming carbide precipitates

30
Q

What makes Nitinol unique among the metals used in dentistry?

a. The rebound in a material when stressed below its proportional limit.
b. The increased percent elongation caused by increasing temperatures.
c. The ability to be strained beyond the proportional limit and still return to its original shape due to lattice structure changes.
d. The forcing of the material in a plastic state into a form that reproduces the same form.
e. The change to its original size that is caused by decreasing the temperature after the material increased in size due to heating as a response to coefficient of thermal expansion.

A

c. The ability to be strained beyond the proportional limit and still return to its original shape due to lattice structure changes.

31
Q

Which of the following definitions is the best definition of annealing?

a. heating a metal above its melting point for refining, alloying
b. heating a metal to allow a redistribution of defects through the lattice structure within the grains
c. heating a metal to allow pouring the molten metal into a mold and allowing it to cool to give it the desired shape
d. heating the metal to produce a change in the lattice structure from austenitic to martensitic
e. heating the metal to allow the transition from a solid solution to an intermetallic compound

A

b. heating a metal to allow a redistribution of defects through the lattice structure within the grains

32
Q
  1. What exist just below point “C”?
    a. an inter-metallic compound
    b. a solid solution
    c. a ferrite
    d. an eutectic
    e. a peritectic
A

d. an eutectic

33
Q
  1. Which set of letters designates a liquidus line?
    a. A-C-E
    b. A-B-C-F-E
    c. D-B-C-F-G
    d. B-C-F
    e. A-C-F-G
A

a. A-C-E

34
Q
  1. What exists in area outlined by E-C-F-E?
    a. a combination of large grain alpha and beta phases
    b. peritectic phase
    c. a pure alpha phase
    d. a pure beta phase
    e. combination of beta phase and liquid
A

e. combination of beta phase and liquid

35
Q
  1. What form of steel would not be stable if held at elevated temperature
    a. anatase
    b. austenite
    c. ferrite
    d. rutile
    e. martensite
A

e. martensite

36
Q
  1. Which of the following is a characteristic Of ceramics?
    a. low modulus
    b. extreme notch sensitivity
    c. higher strength in compression than shear
    d. refractory to heat
    e. higher strength in tension Or shear
A

a. low modulus

37
Q
  1. Which of the following designates the oxide the main constituent of most ceramics and glasses?
    a. silica
    b. silicon
    c. silicone
    d. silicosis
    e. silane
A

a. silica

38
Q
  1. Which of the following is ggg a strengthening mechanism for a ceramic material?
    a. Cooling the porcelain slowly so that the amorphous structure is more uniforrn.
    b. Supporting the ceramic by bonding to a metal.
    c. Modifying the surface through a glazing procedure.
    d. Producing partial devitrification in a porcelain structure.
    e. Producing compression stress on the surface of the material by cooling processes.
A

a. Cooling the porcelain slowly so that the amorphous structure is more uniforrn.

39
Q
  1. Methacrylate is the basis of most of the monomers used in dentistry and methyl methacrylate is the simplest and may still be the most commonly used.
    What is the chemical structure Of methyl methacrylate?
    A.
    B.
    C.
    D.
    E.
A

E.

40
Q
  1. Which of the following is a description of addition polymerization?
    a. develops high molecular weight polymer late in the reaction very rapid polymerization
    b. the alternative name for the reaction is chain growth reaction
    c. usually vinyl (carbon carbon double bond) monomers provide the reactive site
    d. there are no by-products created from the polymerization process
    e. the polymerization requires an enero’ Input to initiate the polymerization process
A

a. develops high molecular weight polymer late in the reaction very rapid polymerization

41
Q
  1. Which Of the following is the most common mechanism used in addition polymerimtion as it is applied in dentistry?
    a. cationic
    b. free radical
    c. condensation
    d. anionic
    e. heterogeneous
A

b. free radical

42
Q
  1. Which Of the following is characteristic Of a highly cross-linked polymer?
    a. degradation rather than melting at high temperatures
    b. covalent bonds holding chains together
    c. swelling in the right solvent
    d. high strength
    e. thermoplasticity
A

e. thermoplasticity

43
Q
  1. Which Of the following is an inorganic polymer?
    a. silicone
    b. polymethyl methacrylate
    c. polyethylene
    d. BisGMA/TEGDMA
    e. polystyrene
A

a. silicone

44
Q
  1. Which of the following reaction in addition polymerization leads to shorter chain lengths without stopping the polymerization process?
    a. condensation
    b. addition
    c. chain transfer
    d. propagation
    e. termination
A

c. chain transfer

45
Q
  1. Which of the following is not a method of initiating addition polymerization?
    a. thermal, increased temperature
    b. entropy, increased disorder
    c. photopolymerization
    d. cold curing
    e. redox
A

b. entropy, increased disorder

46
Q
  1. What role does have in a free radical addition polymerization?
    a. plasticizer
    b. catalyst
    c. inhibitor
    d. initiator
    e. comonomer
A

c. inhibitor

47
Q
  1. What is the effect of an inhibitor on the polymerization reaction when it starts?
    a. It limits the size of the polymer produced in the reaction.
    b. In increases the temperature to start an initiator.
    c. It delays the start of the reaction slightly.
    d. It increases the distribution of the sizes Of the polymer chains resulting from the reaction.
    e. It decreases the cross-linking in a polymer that has a tendency to cross-link.
A

c. It delays the start of the reaction slightly.

48
Q
  1. The rate of change from the monomeric state to the polymeric state and the increase in the number of monomers incorporated into the polymer can be monitored for methacrylates most efficiently and accurately by which of the following procedures?
    a. using change in the area of an absorption peak at a specific wavelength in the IR spectrum
    b. monitoring the amount of temperature change that takes place in the exothermic reaction
    c. measuring the increase in absorption of visible light, or increase in opacity
    d. monitoring the change in weight of the material
    e. measuring the evaporation of monomer from the solid as the polymer forms
A

a. using change in the area of an absorption peak at a specific wavelength in the IR spectrum

49
Q
  1. Heating a solid polymer through its glass transition temperature does which of the following?
    a. Decomposes the polymer chains back to their monomeric state.
    b. Makes a cross-linked solid polymer a liquid, fluid material.
    c. Converts the material from a ceramic state to a glassy state.
    d. Converts a cross-linked material from a glassy state to a rubbery state.
    e. Decreases the materials coefficient of thermal expansion.
A

d. Converts a cross-linked material from a glassy state to a rubbery state.

50
Q
  1. What region of the polymer is most affected when passing through the transition temperature?
    a. the martensitic region
    b. the austenitic region
    c. the crystalline region
    d. the amorphous region
    e. the cross-linked region
A

d. the amorphous region

51
Q
  1. Plasticizers can be part of a polymer system. How do they work?
    a. They lubricate the polymer chains to allow more movement.
    b. They increase the densigr Of the polymer thus increasing the toughness of the material.
    c. They break up the chain alignments to decrease the inter-chain secondary bonding.
    d. They slow the polymerization reaction which decreases the molecular weight of the final polymer chains and thus making it softer.
    e. They increase the rate of polymerization which decreases the molecular weight of the final polymer chains and thus making it softer.
A

c. They break up the chain alignments to decrease the inter-chain secondary bonding.

52
Q
  1. Which of the following is a common initiator for a free radical polymerization which allows chemical curing at elevated temperatures?
    a. dibutyl phthalate
    b. tertiary amine
    c. BisGMA
    d. butyl methacrylate
    e. benzoyl peroxide
A

e. benzoyl peroxide

53
Q
  1. Which of the following is needed to make photoinitiation efficient in the blue region of light exposure for camphorquinone?
    a. dibutyl phthalate
    b. tertiary amine
    c. BisGMA
    d. butyl methacrylate
    e. benzoyl peroxide
A

b. tertiary amine

54
Q
  1. Which Of the following terms describes a polymer that can be reshaped to a new rigid from by heating to a temperature that allows reshaping and then cooling to solidify the new form?
    a. a thermoset
    b. an elastomeric
    c. a cross-linked network
    d. a thermoplastic
    e. a dendrimer
A

d. a thermoplastic

55
Q
  1. Which Of the following monomers would by themselves produce a cross-linked polymer?
    a. octyl methacrylate
    b. dibutyl phthalate
    c. methyl acrylate
    d. biphenol-A diglycidyl methacrylate
    e. methyl methacrylate
A

d. biphenol-A diglycidyl methacrylate

56
Q
  1. What is an inonomer?
    a. polymer or oligomer that has many charged species extending off of the backbone
    b. A polymer or oligomer that exhibits extensive plasticity
    c. A polyrner or oligomer that exhibits extensive elasticity
    d. A polymer or oligomer that has multiple polymerizing functional units
    e. A polymer Or oligomer that Can be converted between an elastic state to a rigid state by changing the temperature
A

a. polymer or oligomer that has many charged species extending off of the backbone

57
Q
  1. Which of the following materials is one that has been a potential component in the monomers used in dentistry that the public has raised concerns about the safety with data supporting some concem in infants and children?
    a. methyl methacrylate
    b. tertiary amine
    c. urethane dimethacrylate
    d. bisphenol A
    e. benzoyl peroxide
A

d. bisphenol A

58
Q
  1. Which of the following is not a method of decreasing overheating when cutting tooth structure?
    a. air/water spray
    b. light contact
    c. short contact time
    d. intermittent application
    e. shorter bur
A

e. shorter bur

59
Q
  1. What is the smear layer?
    a. a microscopic deformed layer at the surface of a material that produces a reflective surface
    b. a layer of debris that remains on the surface of a tooth after cutting that is not removed by washing with an air/water spray
    c. a layer of atoms at the surface of a material that has unsatisfied bonds available
    d. a layer Of fluoride rich tooth structure that is resistant to acid etching
    e. a layer of reparative dentin that results from any potential insult to the tooth that is totally disorganized
A

b. a layer of debris that remains on the surface of a tooth after cutting that is not removed by washing with an air/water spray

60
Q
  1. What was the effect Of MMPs (matrix metalloproteinases) that are currently being researched in relation to bonding?
    a. These are enzymes that attack collagen that is part of the dentin bonding mechanism.
    b. These are metal ion concentrated proteins that enhance the bond to dentin.
    c. These are metal ion concentrated proteins that enhance the bond to enamel.
    d. These are proteins that are released upon etching dentin that can inhibit bacterial
    e. These are proteins in the matrix of the dentin that resist acid etching
A

a. These are enzymes that attack collagen that is part of the dentin bonding mechanism.

61
Q
  1. When etching enamel with phosphoric acid what is the result?
    a. the interdigitation of grains of the hydroxyapatite with free collagen fibers
    b. the removal Of debris leaving a smooth surface with high surface tension to improve the attraction of the liquid monomer
    c. the removal of tubular plugs that allows the resin to penetrate deep into the tooth structure locking the polymerized resin into the tooth
    d. the production of enamel tags that are approximately 25 microns deep
    e. the coalescence of with phosphate modified hydroxyapatite
A

d. the production of enamel tags that are approximately 25 microns deep

62
Q
  1. Why is amorphous calcium phosphate of interest as a treatment in dentistry?
    a. It has a high solubility that will allow it to deposit on tooth structure and may help to prevent demineralize of the tooth.
    b. It can produce a condition at the pulpal surface that can allow the formation of reparative dentin to seal a pulp exposure.
    c. It has a high intrinsic Strength that can “cement” the enamel prisms together.
    d. It can interact with proteins to make a synthetic dentin that can be used to restore the bulk Of the tooth.
    e. It has a refractive index that will allow it to match the tooth structure and produce an esthetic restoration.
A

a. It has a high solubility that will allow it to deposit on tooth structure and may help to prevent demineralize of the tooth.

63
Q
  1. Which of the following is not a mechanism of producing a whitened tooth?
    a. reduction Of oxidized species in the dentin
    b. dehydration of tooth structure
    c. removing debris from the tooth surface
    d. oxidation of chemicals in the reduced, colored state
    e. increased refractive index mismatch by removing some tooth material from the pores in enamel
A

a. reduction Of oxidized species in the dentin

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