Dental Materials Properties And Manipulation 10th Edition by John M. Powers – Test Bank

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INSTANT DOWNLOAD COMPLETE TEST BANK WITH ANSWERS

 

Dental Materials Properties And Manipulation 10th Edition by John M. Powers – Test Bank

 

Sample  Questions

 

Powers: Dental Materials, 10th Edition

 

Chapter 02: Properties of Materials

 

Test Bank

 

MULTIPLE CHOICE

 

  1. For which of the following materials do dimensional changes occur during setting as a result of a chemical reaction?
A. Wax patterns
B. Gold restorations
C. Elastomeric impression materials
D. A and C
E. B and C

 

 

ANS:   C

 

  Feedback
A Wax patterns undergo dimensional changes from cooling during fabrication.
B Gold restorations undergo dimensional changes from cooling during fabrication.
C Dimensional changes occur during setting as a result of a chemical reaction with elastomeric impression materials. Resin composite materials also set as a result of a chemical reaction and undergo shrinkage.
D A and C are incorrect answers.
E B is an incorrect answer, and C is a correct answer.

 

 

REF:    Pg. 15

 

  1. Dimensional change usually is expressed as a percentage of:
A. the compressive strength.
B. the shear strength.
C. the tensile strength.
D. an original length or volume.
E. the final length or volume.

 

 

ANS:   D

 

  Feedback
A Compressive strength is a measure of stress that may result when force is applied to a material.
B Shear strength is a measure of stress that may result when force is applied to a material.
C Tensile strength is a measure of stress that may result when force is applied to a material.
D The dimensional change usually is expressed as a percentage of an original length or volume, not the final length or volume.
E The dimensional change usually is expressed as a percentage of an original length or volume, not the final length or volume.

 

 

REF:    Pg. 15

 

  1. The volumetric dimensional change is equal to _____ times the linear dimensional change.
A. two
B. three
C. four
D. six

 

 

ANS:   B

 

  Feedback
A Two is a distracter.
B The volumetric dimensional change is equal to three times the linear dimensional change. Volume is described as length times width times depth (or height).
C Four is a distracter.
D Six is a distracter.

 

 

REF:    Pg. 15

 

  1. Because the thermal expansion of a restorative material usually does not match that of the tooth structure, a differential expansion or contraction occurs that may result in leakage of oral fluids between the restoration and tooth.
A. Both parts of the statement are true.
B. Both parts of the statement are false.
C. The first part of the statement is true; the second part is false.
D. The first part of the statement is false; the second part is true.

 

 

ANS:   A

 

  Feedback
A Both parts of the statement are true.
B Both parts of the statement are true.
C Both parts of the statement are true.
D Both parts of the statement are true.

 

 

REF:    Pg. 15

 

  1. A new addition silicone impression material is tested for linear dimensional change upon setting. The result of –0.34% indicates that _____ took place within 24 hours after setting.
A. linear expansion
B. linear shrinkage
C. thermal expansion
D. thermal shrinkage

 

 

ANS:   B

 

  Feedback
A Linear thermal expansion is expressed as a coefficient of thermal expansion.
B The result is a negative number which indicates shrinkage took place.
C Thermal expansion is measured by determination of the difference in the length of a specimen at two temperatures.
D Shrinkage is measured by determination of the difference in the length of a specimen at two temperatures.

 

 

REF:    Pg. 16

 

  1. The thermal coefficient of expansion _____ uniform throughout the entire temperature range and is usually _____ for liquids than solids.
A. is; lower
B. is; higher
C. is not; lower
D. is not; higher

 

 

ANS:   D

 

  Feedback
A The thermal coefficient of expansion for a solid generally increases at some point as the temperature is increased.
B The thermal coefficient of expansion for a solid generally increases at some point as the temperature is increased.
C The thermal coefficient of expansion for a solid generally increases at some point as the temperature is increased.
D The thermal coefficient of expansion is not uniform throughout the entire temperature range and is usually higher for liquids than solids.

 

 

REF:    Pg. 16

 

  1. Which of the following restorative materials has a linear thermal coefficient of expansion that is smaller than that of human teeth?
A. Dental amalgam
B. Ceramics
C. Composites
D. Unfilled acrylics and sealants

 

 

ANS:   B

 

  Feedback
A The linear thermal coefficient of expansion of dental amalgam is 28.
B Ceramics have a linear thermal coefficient of expansion of 14. Teeth have a linear thermal coefficient of expansion of 15.
C The linear thermal coefficient of expansion of composites is 68.
D The linear thermal coefficient of expansion of unfilled acrylics and sealants is 100.

 

 

REF:    Pg. 16

 

  1. Which of the following dental restorative materials has a linear coefficient of thermal expansion closest to teeth?
A. Glass ionomer base
B. Dental amalgam
C. Composites
D. Gold alloys
E. Unfilled acrylics and sealants

 

 

ANS:   D

 

  Feedback
A Glass ionomer base has a linear coefficient of thermal expansion of 10-11.
B Dental amalgam has a linear coefficient of thermal expansion of 22-28.
C Composites have a linear coefficient of thermal expansion of 25-68.
D Gold alloys have a linear coefficient of thermal expansion that is closest to teeth.
E Unfilled acrylics and sealants have a linear coefficient of thermal expansion of 70-100.

 

 

REF:    Pg. 15

 

  1. _____ occurs as the result of a discrepancy between the linear thermal coefficient of expansion between teeth and the restorative material if there is no bonding.
A. Stress
B. Strain
C. Elastic modulus
D. Percolation
E. Yield strength

 

 

ANS:   D

 

  Feedback
A If the restoration is bonded, then stress occurs at the interface of the tooth and restoration.
B Strain occurs as result of the change in length or deformation by unit.
C Elastic modulus equals the ratio of stress to strain.
D Percolation occurs as the result of a discrepancy between the linear thermal coefficient of expansion between teeth and the restorative material. It is thought to be undesirable due to possible irritation to the dental pulp and recurrent decay.
E Yield strength is affected by stress at some arbitrary value.

 

 

REF:    Pg. 17

 

  1. Percolation is thought to decrease with time following insertion of which of the following dental restorative materials?
A. Filled resin composite
B. Unfilled acrylic resin
C. Cast gold
D. Dental amalgam
E. Ceramic

 

 

ANS:   D

 

  Feedback
A Filled resin composite is restoration that is either bonded or cemented into place. Percolation related to these restorations would place stress at the interface, which over time would lead to failure of the bond.
B Unfilled acrylic resin is restoration that is either bonded or cemented into place. Percolation related to these restorations would place stress at the interface, which over time would lead to failure of the bond.
C Cast gold is restoration that is either bonded or cemented into place. Percolation related to these restorations would place stress at the interface, which over time would lead to failure of the bond.
D Percolation is thought to decrease with time with dental amalgam, presumably as a result of the space being filled with corrosion products from the amalgam.
E Ceramic is restoration that is either bonded or cemented into place. Percolation related to these restorations would place stress at the interface, which over time would lead to failure of the bond.

 

 

REF:    Pg. 18

 

  1. _____ is used as a measure of heat transferred.
A. Linear coefficient of thermal expansion
B. Thermal conductivity
C. Galvanism
D. Absorption
E. Adsorption

 

 

ANS:   B

 

  Feedback
A Linear coefficient of thermal expansion is determined by the length of a specimen at two temperatures.
B Thermal conductivity is used as a measure of heat transferred.
C Galvanism is the generation of an electric current a patient can feel.
D Absorption refers to uptake of liquid.
E Adsorption refers to concentration of molecules at the surface of a solid or liquid.

 

 

REF:    Pg. 18

 

  1. Which of the following dental restorative materials has the greatest thermal conductivity?
A. Dental amalgam
B. Resin composites
C. Gold alloys
D. Unfilled acrylics
E. Ceramic

 

 

ANS:   C

 

  Feedback
A The thermal conductivity of dental amalgam is substantially lower than gold.
B Resin composites have thermal conductivities comparable to tooth structure.
C Gold alloys have the greatest thermal conductivity.
D Unfilled acrylics have lower thermal conductivity than enamel.
E Ceramic has thermal conductivity comparable to tooth structure.

 

 

REF:    Pg. 16

 

  1. Which of the following restorative materials have thermal conductivity that is most similar to tooth structure?
A. Dental amalgam
B. Composites
C. Gold alloys
D. Zinc phosphate cement
E. Zinc oxide–eugenol cement

 

 

ANS:   B

 

  Feedback
A Dental amalgam has some thermal conductivity but not at a level similar to tooth structure.
B Composites have thermal conductivity most similar to tooth structure.
C Gold alloys have thermal conductivity higher than tooth structure.
D Zinc phosphate cement is a poor conductor of temperature and is used for insulating bases.
E Zinc oxide–eugenol cement is a poor conductor of temperature and is used for insulating bases.

 

 

REF:    Pg. 16

 

  1. Cavity varnishes and liners are ineffective as thermal insulators because they:
A. have high thermal conductivity.
B. have a high coefficient of thermal expansion.
C. have a low coefficient of thermal expansion.
D. are used in thin layers.

 

 

ANS:   D

 

  Feedback
A Varnishes and liners have low thermal conductivity.
B High coefficient of thermal expansion is a measurement of how much a material expands.
C Low coefficient of thermal expansion is a measurement of how much a material expands.
D Cavity varnishes and liners have low thermal conductivities but are used in layers so thin that they are ineffective as thermal insulators.

 

 

REF:    Pg. 21

 

  1. Which of the following is an electrical property of interest in the mouth?
A. Coefficient of thermal expansion
B. Ductility
C. Elastic modulus
D. Galvanism
E. Percolation

 

 

ANS:   D

 

  Feedback
A Coefficient of thermal expansion measures how much a material expands.
B Ductility is the percent of elongation.
C Elastic modulus is equal to the ratio of stress to strain in the liner portion of the stress-strain curve.
D Galvanism is an electrical property. Galvanism results from the presence of dissimilar metals in the mouth. Metals placed in an electrolyte have various inherent tendencies to go into solution.
E Percolation occurs as the result of a discrepancy between the linear thermal coefficient of expansion between teeth and the restorative material.

 

 

REF:    Pg. 16

 

  1. Given a schematic sketch of two opposing teeth, one with a temporary aluminum alloy crown and the other with a gold crown, the electrolyte would be the:
A. temporary aluminum alloy crown.
B. gold crown.
C. saliva.
D. difference in electrical potential.

 

 

ANS:   C

 

  Feedback
A Temporary aluminum alloy crown has a tendency to go into solution.
B Gold crown does not go into solution.
C The saliva functions as the electrolyte.
D The difference in electrical potential in this case would be 2.69 volts. The patient experiences pain and a metallic taste.

 

 

REF:    Pg. 16

 

  1. _____ refers to the uptake of liquid by a bulk solid.
A. Absorption
B. Adsorption
C. Hydrophilic
D. Hydrophobic

 

 

ANS:   A

 

  Feedback
A Absorption refers to the uptake of liquid by a bulk solid.
B Adsorption indicates concentration of molecules at the surface of a solid or liquid.
C Hydrophilic surface is readily wetted if the solution is water.
D Hydrophobic surface is resistant to wetting if the solution is water.

 

 

REF:    Pg. 17

 

  1. Which of the following terms indicates concentration of molecules at the surface of a solid or liquid?
A. Corrosion
B. Hydrophilic
C. Absorption
D. Adsorption

 

 

ANS:   D

 

  Feedback
A Corrosion is the dissolution of metals in the mouth.
B Hydrophilic surface is readily wetted if the solution is water.
C Absorption is the uptake of liquid by a bulk solid.
D Adsorption indicates concentration of molecules at the surface of a solid or liquid.

 

 

REF:    Pg. 17

 

  1. With regard to wettability and water, a low contact angle indicates:
A. the material is hydrophilic.
B. the material is hydrophobic.
C. the contact angle is greater than 90°.
D. both A and C.
E. both B and C.

 

 

ANS:   A

 

  Feedback
A A low contact angle indicates the material is hydrophilic.
B If the contact angle is greater than 90°, poor wetting occurs
C The material is considered hydrophobic if the liquid is water.
D A is correct, and C is incorrect.
E B and C are incorrect.

 

 

REF:    Pg. 17

 

  1. Which of the following choices encourage good wetting?
A. High-energy solid
B. Low-energy solid
C. High-energy liquid
D. A and C
E. B and C

 

 

ANS:   A

 

  Feedback
A High-energy solids and low-energy liquids encourage good wetting.
B Liquids bead up on low-energy solids.
C High-energy liquids can be made more wettable by adding a wetting agent.
D A is correct, and C is incorrect
E B and C are incorrect.

 

 

REF:    Pg. 17

 

  1. The greatest biting forces are on:
A. molars.
B. bicuspids.
C. cuspids.
D. incisors.

 

 

ANS:   A

 

  Feedback
A The greatest biting forces are on molars.
B Bicuspids’ maximum biting forces decrease from the molar to the incisor region.
C Cuspids’ maximum biting forces decrease from the molar to the incisor region.
D Incisors’ maximum biting forces decrease from the molar to the incisor region.

 

 

REF:    Pg. 17

 

  1. Patients with dentures can apply about ____% of the force of those with normal dentition.
A. 10
B. 19
C. 50
D. 90
E. 150

 

 

ANS:   B

 

  Feedback
A Patients with dentures can apply about 19% of the force of those with normal dentition.
B Patients with dentures can apply about 19% of the force of those with normal dentition.
C Patients with dentures can apply about 19% of the force of those with normal dentition.
D Patients with dentures can apply about 19% of the force of those with normal dentition.
E Patients with dentures can apply about 19% of the force of those with normal dentition.

 

 

REF:    Pg. 17

 

  1. The ratio of the force to the area is called:
A. stress.
B. strain.
C. elastic modulus.
D. tensile strength.

 

 

ANS:   A

 

  Feedback
A The ratio of the force to the area is called stress.
B Strain changes in length per unit of a material produced by stress.
C Elastic modulus is equal to the ratio of the stress to the strain.
D Tensile strength results when a material fractures from tensile stress.

 

 

REF:    Pg. 17

 

  1. For a given force, the _____ the area over which it is applied, the _____ the value of the stress.
A. smaller; smaller
B. smaller; larger
C. larger; larger
D. A and C
E. B and C

 

 

ANS:   B

 

  Feedback
A The smaller the area over which force is applied, the larger the value of stress.
B The smaller the area over which force is applied, the larger the value of stress.
C The smaller the area over which force is applied, the larger the value of stress.
D The smaller the area over which force is applied, the larger the value of stress.
E The smaller the area over which force is applied, the larger the value of stress.

 

 

REF:    Pg. 17

 

  1. Which of the following statements is true of the proportional limit?
A. Below the proportional limit a material is plastic, and above the proportional limit it is elastic.
B. Below the proportional limit a material is elastic, and above the proportional limit it is plastic.
C. A material is elastic both below and above the proportional limit.
D. A material is plastic both below and above the proportional limit.

 

 

ANS:   B

 

  Feedback
A A restoration can be classified as a clinical failure if deformation occurs beyond set limits.
B Below the proportional limit a material is elastic, and above the proportional limit it is plastic.
C A restoration can be classified as a clinical failure if deformation occurs beyond set limits.
D A restoration can be classified as a clinical failure if deformation occurs beyond set limits.

 

 

REF:    Pg. 19

 

  1. Which of the following statements is true of the tensile and compressive strengths of a material?
A. They may be significantly different.
B. Brittle materials have small differences in tensile and compressive strength.
C. Brittle materials are stronger in tension than in compression.
D. A, B, and C are true.
E. A and C are true.

 

 

ANS:   A

 

  Feedback
A The tensile and compressive strength of a material may be significantly different.
B Brittle materials such as human enamel, amalgam, and composites have large differences and are stronger in compression than in tension.
C Brittle materials such as human enamel, amalgam, and composites have large differences and are stronger in compression than in tension.
D Brittle materials such as human enamel, amalgam, and composites have large differences and are stronger in compression than in tension.
E Brittle materials such as human enamel, amalgam, and composites have large differences and are stronger in compression than in tension.

 

 

REF:    Pg. 19

 

  1. The energy required to fracture a material is a measure of its:
A. resilience.
B. toughness.
C. ductility.
D. malleability.

 

 

ANS:   B

 

  Feedback
A Resilience is the energy required to deform a material.
B The energy required to fracture a material is a measure of its toughness.
C Ductility is the percent of elongation.
D Malleability is the percent of compression.

 

 

REF:    Pg. 20

 

  1. Which of the following statements is true of the measure of Knoop hardness?
A. Hardness is directly related to yield strength and wear resistance.
B. It is obtained by measurement of the short diagonal of an indentation from a diamond indenter.
C. The larger the indentation, the smaller the value.
D. Enamel has a lower Knoop hardness value than dentin and cementum.

 

 

ANS:   C

 

  Feedback
A In general, no direct relationship exists between hardness and yield strength and wear resistance.
B In general, no direct relationship exists between hardness and yield strength and wear resistance.
C The larger the indentation of the measurement of the long diagonal from a diamond indenter, the smaller the Knoop hardness value.
D Enamel has a higher Knoop hardness value than dentin and cementum.

 

 

REF:    Pg. 21

 

  1. Analysis of the strain–time curve indicates that the _____ the time and the _____ force applied to the impression material, the lower the permanent strain and the more accurate the impression.
A. shorter; less
B. longer; less
C. shorter; more
D. longer; more

 

 

ANS:   A

 

  Feedback
A The shorter the time and the less force applied to the impression material, the lower the permanent strain and the more accurate the impression.
B Longer time will result in more force to the material.
C Shorter time will result in less force to the material.
D Longer time will result in more force to the material and compromise the accuracy of the impression.

 

 

REF:    Pg. 21

 

  1. Dimensional change may occur during setting as a result of:
A. chemical reaction.
B. volumetric change.
C. cooling.
D. all of the above.
E. only A and C.

 

 

ANS:   E

 

  Feedback
A A and C are correct answers.
B Volumetric change is more difficult to measure.
C A and C are correct answers.
D A and C are correct answers.
E Dimensional changes may occur during setting as a result of a chemical reaction, such as with elastomeric impression materials or resin composite restorative materials, or from the cooling of wax patterns or gold restorations during fabrication.

 

 

REF:    Pg. 15

 

  1. Expansion and contraction rates between dental materials and tooth structure caused by temperature change vary. Gaps at the margins allow fluids to enter the space. This is known as:
A. coefficient of thermal expansion.
B. thermal conductivity.
C. dimensional change.
D. percolation.

 

 

ANS:   D

 

  Feedback
A Coefficient of thermal expansion is expressed as the linear difference of a specimen at two temperatures.
B Thermal conductivity is used to measure heat transference.
C Dimensional change is expressed as a percent of the original length.
D Small gaps result at the junction between the two materials. Oral fluids can penetrate this space. When the temperature returns to normal, this fluid is forced out of the space. This phenomenon is called percolation.

 

 

REF:    Pg. 15

 

  1. Of the following materials, which has the closest coefficient of expansion to tooth structure?
A. Amalgam
B. Ceramic
C. Filled polymers
D. Composite resins

 

 

ANS:   B

 

  Feedback
A Values for amalgam and composites are about two to five times those of human teeth.
B Ceramic is the closest, being one half to one third, and gold alloys being approximately the same as for human teeth.
C Values for unfilled polymers, however, are five to seven times those of teeth.
D Values for amalgam and composites are about two to five times those of human teeth.

 

 

REF:    Pg. 15

 

  1. Which of the following materials has the highest rating related to thermal conductivity?
A. Enamel
B. Glass ionomer
C. Gold alloy
D. Dentin

 

 

ANS:   C

 

  Feedback
A Human enamel and dentin are poor thermal conductors.
B Glass ionomer cement bases closely replace lost tooth structure with respect to thermal conductivity.
C Human enamel and dentin are poor thermal conductors compared with gold alloys and dental amalgam, although amalgam is substantially lower than gold.
D Human enamel and dentin are poor thermal conductors.

 

 

REF:    Pg. 16

 

  1. Corrosion is the result of:
A. contact of two dissimilar metals in the mouth.
B. poor oral hygiene around restorations.
C. acidic food and drink.
D. A and C only.

 

 

ANS:   D

 

  Feedback
A A and C are correct.
B Poor oral hygiene around restorations may result in recurrent caries formation.
C A and C are correct.
D Corrosion also can result from this same condition when adjacent restorations are of dissimilar metals. Corrosion also may result from chemical attack of metals by components in food or saliva.

 

 

REF:    Pg. 16

 

  1. A metallic taste in the mouth may be a result of:
A. galvanism.
B. corrosion.
C. contamination.
D. percolation.

 

 

ANS:   A

 

  Feedback
A When the two restorations touch, current flows because the potential difference is 2.69 volts, and the patient experiences pain and frequently complains of a metallic taste.
B Corrosion is a result of the same condition. As a result of the galvanic action, material goes into solution, and roughness and pitting occur.
C Corrosion may occur if a gold alloy is contaminated with a metal such as iron during handling in the dental laboratory
D Small gaps result at the junction between the two materials. Oral fluids can penetrate this space. When the temperature returns to normal, this fluid is forced out of the space. This phenomenon is called percolation.

 

 

REF:    Pg. 16

 

  1. If a liquid presents a contact angle of wettability greater than 90°, the material is said to be:
A. thixotropic.
B. hydrophilic.
C. hydrophobic.
D. viscous.

 

 

ANS:   C

 

  Feedback
A Thixotropic materials require force to be distributed.
B Hydrophilic materials flow readily.
C If a contact angle is greater than 90°, poor wetting occurs (hydrophobic if the liquid is water).
D Viscosity is related to the thickness of a material and may be affected by temperature.

 

 

REF:    Pg. 17

 

  1. Which of the following is not a form of stress?
A. Compressive
B. Flexure
C. Strain
D. Shear

 

 

ANS:   C

 

  Feedback
A Compressive is a type of stress that may result when a force is applied to a material.
B Flexure is a type of stress that may result when a force is applied to a material.
C Strain is the change in length per unit length of a material produced by stress.
D Shear is a type of stress that may result when a force is applied to a material.

 

 

REF:    Pg. 18

 

  1. The change in the length or deformation of a material when subjected to force is:
A. flexure.
B. strain.
C. shear.
D. tensile.

 

 

ANS:   B

 

  Feedback
A Flexure is a type of stress.
B Strain is the change in length or deformation per unit length when a material is subjected to a force.
C Shear is a type of stress.
D Tensile is a type of stress.

 

 

REF:    Pg. 17

 

  1. Deformation of a material becomes permanent when the material reaches its:
A. elastic modulus.
B. stress-strain curve.
C. ultimate strength.
D. yield strength.

 

 

ANS:   D

 

  Feedback
A Elastic modulus is equal to the ratio of the stress to the strain.
B Stress-strain curve is the application of various forces to determine the corresponding values of stress and strain.
C Ultimate strength is the stress at which fracture occurs.
D Yield strength is the measure of the stress allowed before permanent deformation.

 

 

REF:    Pg. 19

 

  1. The hardness of a dental material is reported in:
A. Knoop hardness.
B. nano-indentation.
C. diamond indenter.
D. dynamic properties.

 

 

ANS:   A

 

  Feedback
A The hardness of dental materials generally is reported in Knoop hardness.
B Nano-indentation measures small indentations from small loads.
C Diamond indenter creates a length of the long diagonal of an indentation.
D Dynamic properties occur at extremely high rates of loading such as an impact.

 

 

REF:    Pg. 21

 

SHORT ANSWER

 

  1. Detail the significance of thermal dimensional change.

 

ANS:

Restorative dental materials are subjected to temperature changes in the mouth. These changes result in dimensional changes in the materials and to the neighboring tooth structure. Because the thermal expansion of the restorative material usually does not match that of the tooth structure, a differential expansion occurs that may result in leakage of oral fluids between the restoration and the tooth.

 

REF:    Pg. 15

 

  1. Compare and contrast the terms absorption and adsorption.

 

ANS:

Absorption refers to the uptake of liquid by the bulk solid. For example, the equilibrium absorption of water by acrylic polymers is in the range of 2%. Adsorption indicates concentration of molecules at the surface of a solid or liquid.

 

REF:    Pg. 17

 

  1. Explain the difference between ductility and malleability.

 

ANS:

The percents of elongation and compression are important properties in that they are measures of ductility and malleability, respectively. These two properties are indications of the amount of plastic strain or deformation that can occur before the material fractures and, as such, indicate the brittleness of the material.

 

REF:    Pg. 20

Powers: Dental Materials, 10th Edition

 

Chapter 04: Direct Esthetic Restorative Materials

 

Test Bank

 

MULTIPLE CHOICE

 

  1. Which of the following is the most popular direct esthetic dental restorative material?
A. Composite
B. Compomer
C. Hybrid ionomer
D. Glass ionomer

 

 

ANS:   A

 

  Feedback
A Composite is the most popular direct esthetic restorative material.
B Compomers have distinct advantages as direct esthetic restorations. However, they are weaker than composite resins and should be used under specific parameters.
C Hybrid ionomers have distinct advantages as direct esthetic restorations. However, they are weaker than composite resins and should be used under specific parameters.
D Glass ionomers have distinct advantages as direct esthetic restorations. However, they are weaker than composite resins and should be used under specific parameters.

 

 

REF:    Pg. 42

 

  1. Which of the following direct esthetic restorative materials releases the least fluoride?
A. Compomer
B. Hybrid ionomer
C. Glass ionomer
D. Composite

 

 

ANS:   D

 

  Feedback
A Compomer contains a fluoride ion that leaches into the tooth structure for added protection.
B Hybrid ionomer contains a fluoride ion that leaches into the tooth structure for added protection.
C Glass ionomer contains a fluoride ion that leaches into the tooth structure for added protection.
D Composite releases the least fluoride.

 

 

REF:    Pg. 42

 

  1. Which of the following is not a direct esthetic restorative material?
A. Composite
B. Ceramic
C. Glass ionomer
D. Compomer

 

 

ANS:   B

 

  Feedback
A Composite is used in direct placement esthetic restorations. Ceramic is used for indirect esthetic restorations.
B Currently, four types of materials are being used as direct esthetic dental restorations: composites, compomers, resin-modified glass ionomers, and glass ionomers.
C Glass ionomer is used in direct placement esthetic restorations. Ceramic is used for indirect esthetic restorations.
D Compomer is used in direct placement esthetic restorations. Ceramic is used for indirect esthetic restorations.

 

 

REF:    Pg. 42

 

  1. Which of the following statements is true of silane in composite materials?
A. Silane forms the dispersed organic filler particles.
B. Silane forms the dispersed inorganic filler particles.
C. Silane is a coupling agent on the filler particles.
D. Silane forms the resin matrix.

 

 

ANS:   C

 

  Feedback
A Silane is a coupling agent that allows bonding of particles. It does not form them.
B Silane is a coupling agent that allows bonding of particles. It does not form them.
C Silane is a coupling agent on the filler particles. Its purpose is to produce a good bond between the matrix and the filler.
D Silane is a coupling agent that allows bonding of particles. It does not form them.

 

 

REF:    Pg. 42

 

  1. Which type of composite has the smallest filler particle size?
A. Microhybrid
B. Microfilled
C. Nanofilled
D. Packable
E. Flowable

 

 

ANS:   C

 

  Feedback
A Microhybrid has particle sizes measured in microns. Nanofilled particles are measured in smaller nanometers.
B Microfilled has particle sizes measured in microns. Nanofilled particles are measured in smaller nanometers.
C Nanofilled composites have the smallest particle size.
D Packable has particle sizes measured in microns. Nanofilled particles are measured in smaller nanometers.
E Flowable has particle sizes measured in microns. Nanofilled particles are measured in smaller nanometers.

 

 

REF:    Pg. 42

 

  1. The setting reaction of a composite restorative material is:
A. gelation.
B. polymerization.
C. hysteresis.
D. reduction.

 

 

ANS:   B

 

  Feedback
A Gelation has reactions not associated with direct esthetic restorations.
B The setting reaction of a composite restorative material is polymerization.
C Hysteresis has reactions not associated with direct esthetic restorations.
D Reduction has reactions not associated with direct esthetic restorations.

 

 

REF:    Pg. 43

 

  1. In a visible, light-curing, direct composite system, the light is absorbed by a(n):
A. diketone, which starts the polymerization reaction in the presence of an organic amine.
B. diketone, which starts the polymerization reaction in the presence of an organic peroxide initiator.
C. organic peroxide initiator and organic amine accelerator.
D. organic peroxide initiator alone.

 

 

ANS:   A

 

  Feedback
A In a visible, light-curing, direct composite system, the light is absorbed by a diketone, which starts the polymerization reaction in the presence of an organic amine.
B In a visible, light-curing, direct composite system, the light is absorbed by a diketone, which starts the polymerization reaction in the presence of an organic amine.
C Organic peroxide initiator activates the two-paste, self-cure systems.
D Organic peroxide initiator activates the two-paste, self-cure systems.

 

 

REF:    Pg. 44

 

  1. Which of the following statements is true of polymerization shrinkage of composite restorative materials?
A. Microfilled composites shrink less than microhybrid composites, because microhybrid composites have less resin.
B. Stresses from polymerization shrinkage cannot exceed the bond strength of a composite to tooth structure.
C. Bulk addition of composite will reduce the effective shrinkage.
D. Incremental addition and polymerization of composite in layers will reduce the effective shrinkage.

 

 

ANS:   D

 

  Feedback
A Microhybrid composites shrink less during setting than microfilled types, because the microhybrid composites have less resin.
B Stresses from polymerization shrinkage can exceed the bond strength of a composite to tooth structure, resulting in marginal leakage.
C Bulk addition will increase the effective shrinkage.
D Incremental addition and polymerization of composite in layers will reduce the effective shrinkage.

 

 

REF:    Pg. 44

 

  1. The more resin matrix, the _____ the linear coefficient of thermal expansion, because the polymer has a _____ value than the filler.
A. higher; higher
B. higher; lower
C. lower; higher
D. lower; lower

 

 

ANS:   A

 

  Feedback
A The more resin matrix, the higher the linear coefficient of thermal expansion, because the polymer has a higher value than the filler.
B Microfilled composites have higher values for thermal expansion than microhybrid composites. Therefore the more resin matrix a material has, the higher the linear coefficient of thermal expansion. The lower the matrix, the lower the value.
C Microfilled composites have higher values for thermal expansion than microhybrid composites. Therefore the more resin matrix a material has, the higher the linear coefficient of thermal expansion. The lower the matrix, the lower the value.
D Microfilled composites have higher values for thermal expansion than microhybrid composites. Therefore the more resin matrix a material has, the higher the linear coefficient of thermal expansion. The lower the matrix, the lower the value.

 

 

REF:    Pg. 44

 

  1. When microhybrid composites are contrasted with microfilled composites:
A. microhybrid composites have more polymerization shrinkage.
B. microfilled composites have a higher linear coefficient of thermal expansion.
C. microhybrid composites have higher water sorption.
D. microfilled composites have higher compressive strength.
E. microhybrid composites have a lower elastic modulus in compression.

 

 

ANS:   B

 

  Feedback
A Microhybrid composites have less polymerization shrinkage.
B Microfilled composites have a higher linear coefficient of thermal expansion.
C Microhybrid composites have lower water sorption.
D Microfilled composites have a lower compressive strength than microhybrid composites.
E Microhybrid composites have a higher elastic modulus in compression than microfilled composites.

 

 

REF:    Pg. 45

 

  1. A bond strength of _____ MPa is an estimated requirement to prevent marginal gaps as a result of polymerization shrinkage during placement of composite restorations.
A. 0.01
B. 1
C. 10
D. 20

 

 

ANS:   D

 

  Feedback
A 0.01 is well below the estimated MPa requirement and would exacerbate the potential for marginal gaps.
B 1 is well below the estimated MPa requirement and would exacerbate the potential for marginal gaps.
C 10 is well below the estimated MPa requirement and would exacerbate the potential for marginal gaps.
D A bond strength of 20 MPa is an estimated requirement to prevent marginal gaps as a result of polymerization shrinkage during placement of composite restorations.

 

 

REF:    Pg. 45

 

  1. Sensitivity associated with placement of composite restorations has been reported in about ____% of cases.
A. 1
B. 10
C. 25
D. 50
E. 75

 

 

ANS:   B

 

  Feedback
A Sensitivity associated with placement of composite restorations has been reported in about 10% of cases.
B Sensitivity associated with placement of composite restorations has been reported in about 10% of cases.
C Sensitivity associated with placement of composite restorations has been reported in about 10% of cases.
D Sensitivity associated with placement of composite restorations has been reported in about 10% of cases.
E Sensitivity associated with placement of composite restorations has been reported in about 10% of cases.

 

 

REF:    Pg. 46

 

  1. Currently acceptable composites for posterior applications require clinical studies demonstrating a loss of surface contour less than _____ µm over a 5-year period.
A. 5
B. 50
C. 100
D. 250
E. 5000

 

 

ANS:   D

 

  Feedback
A Currently acceptable composites for posterior applications require clinical studies demonstrating a loss of surface contour less than 250 µm over a 5-year period, or an average of 50 µm per year of clinical service.
B Currently acceptable composites for posterior applications require clinical studies demonstrating a loss of surface contour less than 250 µm over a 5-year period, or an average of 50 µm per year of clinical service.
C Currently acceptable composites for posterior applications require clinical studies demonstrating a loss of surface contour less than 250 µm over a 5-year period, or an average of 50 µm per year of clinical service.
D Currently acceptable composites for posterior applications require clinical studies demonstrating a loss of surface contour less than 250 µm over a 5-year period, or an average of 50 µm per year of clinical service.
E Currently acceptable composites for posterior applications require clinical studies demonstrating a loss of surface contour less than 250 µm over a 5-year period, or an average of 50 µm per year of clinical service.

 

 

REF:    Pg. 46

 

  1. The most likely cause(s) of sensitivity following placement of composite restorations is(are):
A. an occlusal interference.
B. the use of acid etchant during placement.
C. induced internal stress.
D. microleakage of bacteria.
E. both C and D.

 

 

ANS:   E

 

  Feedback
A Effective finishing and polishing of the restoration at the time of placement will eliminate high occlusion.
B Use of a low-strength liner prior to etching will protect the pulp.
C C and D are correct.
D C and D are correct.
E The most likely causes of sensitivity following placement of composite restorations are induced internal stress and microleakage of bacteria.

 

 

REF:    Pg. 46

 

  1. With _____-generation bond agents, etching and priming are accomplished at the same time, and rinsing is not required.
A. third
B. fourth
C. fifth
D. sixth

 

 

ANS:   D

 

  Feedback
A Third-generation bond agents are all associated with multiple steps.
B Fourth-generation bond agents are all associated with multiple steps.
C Fifth-generation bond agents are all associated with multiple steps.
D With sixth- and seventh-generation bonding agents, etching and priming are accomplished at the same time, and rinsing is not required.

 

 

REF:    Pg. 46

 

  1. Which of the following statements is true of single- and two-paste composites?
A. Compules are a component of two-paste composites.
B. Single-paste composites are light activated.
C. An automix syringe is a component of single-paste composites.
D. Single-paste composites may be dual cured.

 

 

ANS:   B

 

  Feedback
A Compules are a component of single-paste composites.
B Single-paste composites are light activated.
C An automix syringe is a component of two-paste composites.
D Some forms of two-paste composites are dual cured.

 

 

REF:    Pg. 46

 

  1. Advantages of placing composite into the plastic tip of a syringe and injecting it into the cavity preparation include that the syringe:
A. allows the use of small mixes.
B. reduces incorporation of voids into the composite during insertion.
C. facilitates placement of the material in the areas of retention.
D. A, B, and C.
E. A and C.

 

 

ANS:   D

 

  Feedback
A A, B, and C are correct.
B A, B, and C are correct.
C A, B, and C are correct.
D Advantages of placing composite into the plastic tip of a syringe and injecting it into the cavity preparation include that the syringe allows the use of small mixes, reduces incorporation of voids into the composite during insertion, and facilitates placement of the material in the areas of retention.
E A, B, and C are correct.

 

 

REF:    Pg. 47

 

  1. Flowable composites:
A. are recommended for low–stress-bearing restorations.
B. have a low modulus of elasticity.
C. have a high modulus of elasticity.
D. A and B.
E. A and C.

 

 

ANS:   D

 

  Feedback
A Flowable composites are recommended for low–stress-bearing restorations. They have a low modulus of elasticity, which is the ratio of stress to strain.
B Flowable composites are recommended for low–stress-bearing restorations. They have a low modulus of elasticity, which is the ratio of stress to strain.
C Flexible materials have a low modulus of elasticity, and stiff materials have a high modulus of elasticity.
D Flowable composites are recommended for low–stress-bearing restorations. They have a low modulus of elasticity, which is the ratio of stress to strain.
E Flowable composites are recommended for low–stress-bearing restorations. They have a low modulus of elasticity, which is the ratio of stress to strain.

 

 

REF:    Pg. 47

 

  1. Which of the following statements is true of flowable composites when contrasted with microhybrid composites? Flowable composites:
A. have a higher filler content than microhybrid composites.
B. exhibit lower polymerization shrinkage than microhybrid composites.
C. have higher wear resistance than microhybrid composites.
D. have lower viscosity than microhybrid composites.

 

 

ANS:   D

 

  Feedback
A Flowable composites have a lower filler content than microhybrid composites.
B This makes them more flexible and well suited for fabrication areas, but they do exhibit more polymerization shrinkage.
C Flowable composites have lower wear resistance than microhybrid composites.
D Flowable composites have lower viscosity than microhybrid composites.

 

 

REF:    Pg. 47

 

  1. Which type of direct composite has a wear rate most similar to dental amalgam?
A. Flowable composite
B. Packable composite
C. Microhybrid composite
D. Microfilled composite

 

 

ANS:   B

 

  Feedback
A Flowable has higher wear rates than is recommended for stress-bearing areas.
B Packable has a low wear rate (3.5 µm/year), similar to that of amalgam.
C Microhybrid has higher wear rates than is recommended for stress-bearing areas.
D Microfilled has higher wear rates than is recommended for stress-bearing areas.

 

 

REF:    Pg. 47

 

  1. Which of the following statements is true when contrasting composite core material with amalgam?
A. Composite can be finished immediately and prepared for a crown at the same appointment, whereas amalgam cannot be prepared for a crown at the same appointment.
B. Composite materials have good color under ceramic, but amalgam does not.
C. Composite materials are easier to contour than amalgam materials.
D. A, B, and C are correct.
E. A and C are correct.

 

 

ANS:   D

 

  Feedback
A A, B, and C are all correct answers.
B A, B, and C are all correct answers.
C A, B, and C are all correct answers.
D Amalgam cannot be prepared for a crown at the same time as the placement appointment because of delayed setting expansion or contraction. Composite materials have better color under ceramic while the silver-gray color of amalgam can bleed through. Composite materials are easier to contour than amalgam materials.
E A, B, and C are all correct answers.

 

 

REF:    Pg. 48

 

  1. Advantages of composite provisional materials over acrylic provisional materials include:
A. lower cost.
B. doughy stage for easier handling.
C. harder, more brittle texture.
D. lower heat release during curing.

 

 

ANS:   D

 

  Feedback
A They are more expensive.
B Acrylic is listed as having a doughy stage for easier handling than composite.
C They are harder and more brittle, which are listed in Table 4-5 as disadvantages of composite.
D Composite provisional materials release less heat during curing than acrylic provisional materials.

 

 

REF:    Pg. 48

 

  1. When composites are repaired, the repair bond strength is about ____% of the cohesive strength of the original composite.
A. 100 to 120
B. 80 to 100
C. 60 to 80
D. 40 to 60
E. 20

 

 

ANS:   C

 

  Feedback
A Option A is higher than the given percent rate.
B Option B is higher than the given percent rate.
C The repair bond strength is about 60 to 80% of the cohesive strength of the original composite.
D Option D is lower than the given percent rate.
E Option E is lower than the given percent rate.

 

 

REF:    Pg. 48

 

  1. Compomers contain:
A. dimethacrylate (Bis-GMA).
B. urethane dimethacrylate (UDMA) oligomers.
C. monomers modified by polyacid groups with fluoride-releasing silicate glasses.
D. a powder of aluminosilicate glass and a water solution of polymers and copolymers of acrylic acid.

 

 

ANS:   C

 

  Feedback
A Bis-GMA is associated with composite resins, microfilled, and microhybrids.
B UDMA is associated with composite resins, microfilled, and microhybrids.
C Compomers contain monomers modified by polyacid groups with fluoride-releasing silicate glasses
D Option D is associated with glass ionomer.

 

 

REF:    Pg. 49

 

  1. It is recommended that glass ionomer restorations be used in Class _____ restorations where esthetics is not critical.
A. I
B. II
C. III
D. IV
E. V

 

 

ANS:   E

 

  Feedback
A Class Is are load-bearing areas, and glass ionomers are not strong enough to withstand biting forces.
B Class IIs are load-bearing areas, and glass ionomers are not strong enough to withstand biting forces.
C Class IIIs are highly visible areas in which esthetics is an issue.
D Class IVs are highly visible areas in which esthetics is an issue.
E It is recommended that glass ionomer restorations be used in Class V restorations where esthetics is not critical. They are recommended for patients with high risk of caries.

 

 

REF:    Pg. 49

 

  1. The smear layer consists of:
A. calcium hydroxide.
B. hydroxyapatite and partially denatured collagen.
C. etchant.
D. primer.
E. adhesive.

 

 

ANS:   B

 

  Feedback
A Calcium hydroxide is used as a low-strength liner and will stimulate the formation of reparative dentin.
B The smear layer consists of hydroxyapatite and partially denatured collagen.
C Etchant removes the smear layer and prepares enamel and dentin to receive the esthetic restoration.
D Primer is related to the bonding process.
E Adhesive is related to the bonding process.

 

 

REF:    Pg. 49

 

  1. Which of the following statements is true regarding composite curing times?
A. Curing times with PAC lights are longer than for QTH or LED lights.
B. Microhybrid composites require longer curing times than microfilled composites.
C. Darker shades require shorter curing times than lighter shades.
D. More opaque composites require longer curing times than more translucent composites.

 

 

ANS:   D

 

  Feedback
A QTH or LED lights are more intense than PAC lights.
B Microfilled composites take longer to cure than microhybrid composites.
C Shade should not affect curing time.
D More opaque composites require longer curing times than more translucent composites.

 

 

REF:    Pg. 51

 

  1. Glass ionomers are typically reserved for which type of restoration?
A. Cervically eroded areas
B. Posterior interproximal lesions
C. Anterior interproximal lesions
D. Pit and fissure lesions

 

 

ANS:   A

 

  Feedback
A Areas of cervical erosion benefit from using glass ionomer.
B Posterior interproximal lesions require a restorative material with more strength and wear resistance.
C Anterior interproximal lesions require a restorative material with more strength and wear resistance.
D Pit and fissure lesions require a restorative material with more strength and wear resistance.

 

 

REF:    Pg. 42

 

  1. Which of the following is not true about composite resin materials?
A. Esthetically pleasing
B. High fluoride content
C. High strength
D. High wear resistance

 

 

ANS:   B

 

  Feedback
A Composite resins are esthetically pleasing, strong, and have high wear resistance.
B Composite resins have little to no fluoride content.
C Composite resins are esthetically pleasing, strong, and have high wear resistance.
D Composite resins are esthetically pleasing, strong, and have high wear resistance.

 

 

REF:    Pg. 42

 

  1. The composition of composite resin material consists of:
A. organic filler particles.
B. inorganic filler particles.
C. resin matrix.
D. all of the above.
E. only B and C.

 

 

ANS:   E

 

  Feedback
A Filler particles in composite resin materials include quartz, lithium aluminum silicate, and barium, strontium, zinc, or ytterbium glasses. All are inorganic materials.
B B and C are correct.
C B and C are correct.
D B and C are correct.
E Composites consist of three phases: resin matrix, dispersed inorganic filler particles, and silane coupling agent on the filler particles to produce a good bond between the matrix and the filler.

 

 

REF:    Pg. 42

 

  1. Organic fillers that are radiopaque include:
A. crystalline silica.
B. lithium aluminum silicate.
C. strontium.
D. all of the above.

 

 

ANS:   C

 

  Feedback
A Crystalline silica fillers are radiolucent.
B Lithium aluminum silicate fillers are radiolucent.
C Fine fillers that contain barium, strontium, zinc, or ytterbium atoms are radiopaque with the radiopacity proportional to the volume fraction of the filler.
D Option C is the only correct answer.

 

 

REF:    Pg. 42

 

  1. Organic fillers that are radiolucent include:
A. crystalline silica.
B. lithium aluminum silicate.
C. strontium.
D. all of the above.
E. only A and B.

 

 

ANS:   E

 

  Feedback
A A and B are correct.
B A and B are correct.
C Strontium is radiopaque.
D A and B are correct.
E Quartz (crystalline silica) and lithium aluminum silicate are not radiopaque.

 

 

REF:    Pg. 42

 

  1. The polymerization reaction of a self-cure composite resin is initiated by:
A. visible curing light system.
B. diketone in the presence of an organic amine.
C. organic peroxide initiator.
D. dimethacrylate.

 

 

ANS:   C

 

  Feedback
A Curing lights relate to a one-paste composite system that uses visible light to cure.
B In self-curing systems, polymerization is accomplished with an organic peroxide initiator and an organic amine accelerator.
C In self-curing systems, polymerization is accomplished with an organic peroxide initiator and an organic amine accelerator.
D Dimethacrylate is a resin matrix.

 

 

REF:    Pg. 44

 

  1. Bond strength is exceeded and gaps occur at the cavosurface margin as a result of:
A. inadequate cure.
B. saliva contamination.
C. inadequate etch.
D. polymerization shrinkage.

 

 

ANS:   D

 

  Feedback
A Inadequate cure affects adhesion rather than strength.
B Saliva contamination affects adhesion rather than strength.
C Inadequate etch affects adhesion rather than strength.
D Even with acid etching of enamel and dentin and use of bonding agents, stresses from polymerization shrinkage can exceed the bond strength of a composite to tooth structure, and, as a result, marginal leakage can occur.

 

 

REF:    Pg. 44

 

  1. Which of the following have the highest rates of thermal expansion?
A. Microfilled composites
B. Macrofilled composites
C. Microhybrid composites
D. Nanofilled composites

 

 

ANS:   A

 

  Feedback
A Microfilled composites have higher values for thermal expansion than microhybrid composites.
B Macrofilled composites have lower values of thermal expansion.
C Microhybrid composites have lower values of thermal expansion.
D Nanofilled composites have lower values of thermal expansion.

 

 

REF:    Pg. 44

 

  1. The elastic modulus of composite materials for posterior restorations is dominated by:
A. stiffness of the filler.
B. low filler content.
C. high filler content.
D. percentage of matrix.

 

 

ANS:   C

 

  Feedback
A Elastic modulus is the stiffness of the material.
B Low filler content materials are susceptible to biting forces.
C The lower filler content of the microfilled composites results in elastic moduli of one-fourth to one-half of the more highly filled microhybrid composites. This stiffness is important in applications in which high biting forces are involved and wear resistance is essential.
D Percentage of matrix affects bonding with fillers.

 

 

REF:    Pg. 45

 

  1. Composite materials are superior materials for anterior restorations because of:
A. minimal surface erosion.
B. minimal degradation in the oral environment.
C. resistance to biting forces.
D. low rate of recurrent caries.

 

 

ANS:   D

 

  Feedback
A The problem with composites is the loss of surface contour of composite restorations in the mouth.
B Anterior restorations suffer from erosive wear from degradation of the composite in the oral environment.
C Anterior restorations suffer abrasive wear from chewing and toothbrushing.
D Clinical studies have shown that composites are superior materials for anterior restorations in which esthetics is essential and occlusal forces are low. Color changes are minimal; marginal adaptation is good; and recurrent decay is low.

 

 

REF:    Pg. 45

 

  1. Postoperative sensitivity can be avoided by:
A. placing smaller layers of material.
B. using a low-strength liner.
C. using a high-strength base.
D. all of the above.
E. only A and C.

 

 

ANS:   D

 

  Feedback
A A, B, and C are correct answers.
B A, B, and C are correct answers.
C A, B, and C are correct answers.
D Incremental placement of the composite, excellent isolation during placement, and use of bases to protect the pulp are recommended solutions.
E A, B, and C are correct answers.

 

 

REF:    Pg. 46

 

  1. In the event that an esthetic material is required for a direct, posterior, load-bearing restoration, ______ composite is the material of choice.
A. packable
B. flowable
C. laboratory
D. core

 

 

ANS:   A

 

  Feedback
A These composites (see Table 4-2) are recommended for use in Class I, II, and VI (MOD) cavity preparations.
B Flowable composites are not strong enough to place in load-bearing areas.
C Laboratory composites are used for indirect restorations.
D Core composites are used to replace tooth structure prior to the placement of a crown.

 

 

REF:    Pg. 47

 

  1. Compomers are recommended for patients with _____ risk.
A. low caries
B. medium caries
C. high caries
D. any level of

 

 

ANS:   B

 

  Feedback
A Low caries risk would not need a material containing a fluoride ion.
B Compomers are recommended for patients with medium caries risk.
C High caries risk might require a material with a higher level of fluoride release.
D Not all patients are candidates for compomer restorative materials.

 

 

REF:    Pg. 49

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