Dental Materials Clinical Applications for Dental Assistants and Dental Hygienists 3rd Edition By W. Stephan Eakle -Test Bank
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Sample
Test
Chapter 03: Physical and Mechanical Properties of Dental Materials
MULTIPLE CHOICE
1. Which
type of bond occurs when two atoms share electrons in their outer shell,
creating full shells for both?
|
a. |
Ionic bond |
|
b. |
Covalent bond |
|
c. |
Metallic bond |
|
d. |
Hydrogen bond |
ANS: B
Covalent bonds occur when two atoms share electrons in their
outer shell, creating full shells for both. Covalent bonds are very strong.
Diamond is a good example of a strong covalent bond; it is hard and has a high
melting point.
REF: p.
20
TOP: Physical Structure (Primary Bonds)
2. Which
of the following is an example of a secondary rather than primary bond?
|
a. |
Ionic bond |
|
b. |
Metallic bond |
|
c. |
Covalent bond |
|
d. |
Hydrogen bond |
ANS: D
A hydrogen bond is an example of a secondary bond. Secondary
bonds are much weaker than primary bonds. Unlike with primary bonds, no
transfer or sharing of electrons occurs. This weakness often leads to
deformation or fracture.
REF: p.
20
TOP: Physical Structure (Secondary Bonds)
3. Which
of the following forms of matter has/have both shape and volume?
4. Solid
5. Liquid
6. Gas
|
a. |
1, 2, 3 |
|
b. |
1, 2 |
|
c. |
2, 3 |
|
d. |
1 |
ANS: D
Solids have the strongest attraction between atoms and molecules
and have both shape and volume, a liquid has volume but no shape, and a gas has
neither definite shape nor volume.
REF: p.
21
TOP: Physical Structure (The Three States of Matter)
4. If
the molecules of a solid are arranged in a random form with no regular pattern,
the solid is called:
|
a. |
thixotropic. |
|
b. |
amorphous. |
|
c. |
malleable. |
|
d. |
ductile. |
ANS: B
If the molecules of a solid are arranged in a random form with
no regular pattern, the solid is called amorphous. The
most stable solids have a regular crystalline structure with molecules in a regularly
spaced pattern.
REF: p.
21
TOP: Physical Structure (Solids)
5. Which
of the following is the hardest material?
|
a. |
Enamel of a tooth |
|
b. |
Cementum of a tooth |
|
c. |
Cast gold restorative
material |
|
d. |
Composite resin restorative
material |
ANS: A
Enamel and porcelain are two of the hardest materials and are
more resistant to being scratched than is cementum on the root or composite
resins or gold crowns. Hardness is the resistance of a solid to penetration.
Hardness is also used to define a material’s resistance to wear and abrasion.
The hardness of a material is used to determine the ability of an abrasive to
scratch or resist scratching the substrate to which it is applied.
REF: pp. 21-22
TOP: Physical Structure (Solids)
6. Which
of the following statements is true concerning desirable properties of dental
materials?
|
a. |
The maximum amount of
stress a material can withstand without breaking is known as the proportional limit. |
|
b. |
Stiffer materials have a
high modulus of elasticity. |
|
c. |
Resilience is the ability
of a material to resist fracture. |
|
d. |
In most cases, metals tend
to be brittle and ceramics tend to be ductile and malleable. |
ANS: B
Stiffer materials have a high modulus of elasticity. The
stiffness of a material is its resistance to deformation and is measured by
Young’s elastic modulus. The maximum amount of stress a material can withstand
without breaking is known as the ultimate
strength. Toughness is the ability of a material to resist
fracture. In most cases, metals tend to be ductile and malleable and ceramics
tend to be brittle.
REF: p.
22
TOP: Physical Structure (Solids)
7. The
higher the viscosity, the greater is a liquid’s ability to resist flow.
Usually, the viscosity of liquids increases as the temperature increases.
|
a. |
Both statements are true. |
|
b. |
Both statements are false. |
|
c. |
The first statement is
true; the second statement is false. |
|
d. |
The first statement is
false; the second statement is true. |
ANS: C
The first statement is true, and the second statement is false.
The higher the viscosity, the greater is a liquid’s ability to resist flow.
Usually, the viscosity of liquids decreases as the temperature increases. Values
of viscosity depend on the nature of the fluid; thin fluids have low viscosity,
and thicker fluids have high viscosity.
REF: p.
23
TOP: Physical Structure (Liquids)
8. Which
of the following are considered to be therapeutic dental materials?
|
a. |
Partial and complete
dentures |
|
b. |
Fluorides and pit and
fissure sealants |
|
c. |
Fillings, inlays, crowns,
bridges, and implants |
|
d. |
Medicated bases and topical
treatments for periodontal disease |
ANS: D
Medicated bases and topical treatments for periodontal disease
are considered to be therapeutic materials used in the treatment of disease.
Fluorides and pit and fissure sealants are preventive materials. The
classification of restorative materials applies to any filling, inlay, crown,
bridge, implant, or partial or complete denture that restores or replaces lost
tooth structure, teeth, or oral tissue.
REF: p.
23
TOP: Application
9. Which
of the following is an example of a direct restorative material?
|
a. |
Porcelain inlay |
|
b. |
Cast gold crown |
|
c. |
Ceramic implant abutment |
|
d. |
Silver dental amalgam
restoration |
ANS: D
A silver dental amalgam restoration is an example of a direct
restorative material. Some materials, such as amalgams and composites, may be fabricated
directly in the mouth. Other materials, because of convenience or toxic or
other physically harmful characteristics, need to be fabricated indirectly
outside the mouth and then placed into the oral environment. Porcelain, for
instance, needs to be fired to temperatures higher than 1000° F, making it
necessary to be fabricated indirectly.
REF: p.
23
TOP: Application
10. Dental
plaster begins with _____ components.
|
a. |
water and powder |
|
b. |
liquid and powder |
|
c. |
paste and liquid |
|
d. |
paste and paste |
ANS: A
Dental plaster begins with water and powder components;
composite restorations may use a paste and a blue light as an initiator. Many
components are classified as catalyst and base; the catalyst is responsible for
the speed at which the reaction occurs and is often the liquid component.
REF: p.
23
TOP: Composition
11. _____
time is the time permitted to manipulate the material in the mouth.
|
a. |
Mixing |
|
b. |
Working |
|
c. |
Initial set |
|
d. |
Final set |
ANS: B
Working time is the time permitted to manipulate the material in
the mouth. Mixing time is the amount of time the auxiliary has to bring the
components together into a homogenous mix. The initial set time begins when the
material can no longer be manipulated in the mouth, and the final set time is
when the material has reached its ultimate state.
REF: p.
24
TOP: Reaction
12. Dual
set materials utilize _____ setting reactions.
|
a. |
both light-activated and chemical |
|
b. |
light-activated but not
chemical |
|
c. |
chemical setting but not
light-activated |
|
d. |
neither light-activated nor
chemical |
ANS: A
Dual set materials utilize both light-activated and chemical
setting reactions. Dual set materials begin with the initiation of the blue
light source and then continue with the chemical set reaction; this also gives
the clinician better control of his or her working time.
REF: p.
24
TOP: Reaction
13. Which
of the following is true concerning initial and final setting times?
|
a. |
Moisture and pressure
controls are frequently important during the initial set. |
|
b. |
The final set always occurs
while the patient is still in the dental office. |
|
c. |
The material must not be
disturbed through the end of the final set. |
|
d. |
Once a material has reached
the initial set, it will not fracture. |
ANS: A
Moisture and pressure controls are frequently important during
the initial set. Moisture contamination, from saliva and blood, during initial
setting time may have an adverse effect on many dental materials, causing them
to fail. Continued firm pressure from biting force or by holding the material
firmly in the mouth is essential for materials needing intimate contact with
the tooth such as dental cements. The material must not be disturbed through
the end of the initial set. The final set may occur while the patient is still
in the dental office or several hours later. Appropriate patient postoperative
instructions on when and what to eat or on placing pressure on the restoration
are essential to avoid fracture of these materials.
REF: p.
24
TOP: Reaction
14. In
general, _____ temperature and _____ humidity will accelerate the reaction of
the material.
|
a. |
high; high |
|
b. |
high; low |
|
c. |
low; high |
|
d. |
low; low |
ANS: A
In general, high temperature and high humidity will accelerate
the reaction of the material, but low temperatures and low humidity will retard
the reaction.
REF: p.
24
TOP: Manipulation
15. Which
of the following is not a primary bond?
|
a. |
Hydrogen |
|
b. |
Covalent |
|
c. |
Metallic |
|
d. |
Ionic |
ANS: A
Primary bonds are the strongest bonds that hold atoms together
because they involve the exchanging or sharing of electrons. There are three
types of primary bonds: ionic bonds, covalent bonds, and metallic bonds.
REF: p.
20
TOP: Physical Structure (Primary Bonds)
16. The
stability of a solid is evaluated by noting:
|
a. |
its atomic mass and number. |
|
b. |
whether or not it is a compound. |
|
c. |
how hard the material is
when set. |
|
d. |
whether the molecules are
arranged uniformly. |
ANS: D
The most stable solids have a regular crystalline structure with
molecules in a regularly spaced pattern. If these molecules are arranged in a
random form with no regular pattern, the solid is less stable and is
called amorphous.
REF: p.
21
TOP: Physical Structure (Solids)
17. What
is the maximum amount of stress a material can take before breaking?
|
a. |
Ultimate capacity |
|
b. |
Ultimate strength |
|
c. |
Material hardness |
|
d. |
Maximum elasticity |
ANS: B
The maximum amount of stress a material can withstand without
breaking is known as its ultimate
strength.
REF: p.
22
TOP: Physical Structure (Solids)
18. Metals
that can withstand dimensional change without breaking are:
|
a. |
tough. |
|
b. |
ductile. |
|
c. |
resilient. |
|
d. |
malleable. |
ANS: B
The orthodontic wire being pulled or stretched under tension is
a measure of its ductility, the amount of dimensional change it can withstand
without breaking.
REF: p.
22
TOP: Physical Structure (Solids)
19. What
is the measure of the weight of a material as compared with its volume?
|
a. |
Density |
|
b. |
Viscosity |
|
c. |
Hardness |
|
d. |
Resistance |
ANS: A
Density is a measure of the weight of a material as compared
with its volume. Viscosity refers to the material’s ability to flow under
pressure. Hardness is a material’s resistance to penetrations.
REF: p.
21
TOP: Physical Structure (Solids)
20. Of
the following, which is not an
application of a material’s classification?
|
a. |
Longevity |
|
b. |
Utilization |
|
c. |
Fabrication |
|
d. |
All of these are correct. |
ANS: D
Materials are classified by their application, how they will be
utilized and fabricated, and their expected longevity.
REF: p.
23
TOP: Application
21. A
_____ material will flow more easily under mechanical pressure.
|
a. |
viscous |
|
b. |
thixotropic |
|
c. |
resistance |
|
d. |
therapeutic |
ANS: B
Thixotropic materials are liquids that flow more easily under
mechanical forces.
REF: p.
23
TOP: Physical Structure (Liquids)
22. Which
of the following would be considered an indirect placement restorative
material?
|
a. |
Gold |
|
b. |
Gold foil |
|
c. |
Amalgam |
|
d. |
Composite resin |
ANS: A
Some materials, because of convenience or toxic or other
physically harmful characteristics, need to be fabricated indirectly outside
the mouth and then placed into the oral environment. Porcelain, for instance,
needs to be fired to temperatures higher than 1000° F; therefore, it must be
fabricated indirectly.
REF: p.
23
TOP: Application
23. What
is the reaction initiated when a catalyst and a base are mixed together?
|
a. |
Chemical |
|
b. |
Physical |
|
c. |
Dual |
|
d. |
All are possible reactions. |
ANS: D
Chemical set materials are those that set through the timed
chemical reaction of the catalyst and the base. Once the two components come in
contact with each other, the chemical reaction begins and continues through the
reaction stage. Light-activated materials use a blue light source to initiate
the reaction stage. Both components are present in the material but do not
react until the material comes in contact with the blue light source, thus
giving the clinician unlimited working time. Dual set materials begin with
initiation of the blue light source and then continue with a chemical set
reaction; this also gives the clinician much better control of his or her
working time.
REF: pp. 24-25
TOP: Reaction
24. Altering
the set ratios of a material for any purpose will do what?
|
a. |
Make the material harder |
|
b. |
Produce adverse results |
|
c. |
Speed up the initial set |
|
d. |
Have little significance |
ANS: B
These ratio changes are variables that permit the clinician to
alter manipulation and reaction times for some materials but are
contraindicated with other materials because of adverse effects. Manufacturers
give direction as to how much variation in ratio the material can withstand
without adverse results and when this will occur.
REF: p.
24
TOP: Manipulation
25. What
will happen if expired materials or improperly stored materials are used?
|
a. |
Render the material
ineffective |
|
b. |
Be of little consequence |
|
c. |
Cause a toxic reaction |
ANS: A
The shelf life of a material refers to the deterioration and
change in quality of the material over time. Attention to the date of
expiration is important for consistency in the optimum characteristics of the
product. Conditions of storage such as temperature and humidity, as well as
type of storage container, may directly affect the material’s shelf life.
REF: p.
24
TOP: Manipulation
MATCHING
Match the items with the correct description below.
|
a. |
Resistance to deformation |
|
b. |
The greatest stress a
structure can withstand without permanent deformation |
|
c. |
The resistance of a solid
to penetration |
|
d. |
The maximum amount of
stress a material can withstand without breaking |
|
e. |
The ability of a material
to resist fracture |
1. Hardness
2. Ultimate
strength
3. Stiffness
4. Proportional
limit
5. Toughness
1. ANS:
C
REF: p.
21
TOP: Physical Structure (Solids)
2. ANS:
D
REF: p.
22
TOP: Physical Structure (Solids)
3. ANS:
A
REF: p.
22
TOP: Physical Structure (Solids)
4. ANS:
B
REF: p.
22
TOP: Physical Structure (Solids)
5. ANS:
E
REF: p.
22
TOP: Physical Structure (Solids)
Match the items with the correct description below.
|
a. |
Begins when the material
can no longer be manipulated in the mouth |
|
b. |
When the material has reached
its ultimate state |
|
c. |
The amount of time the
auxiliary has to bring the components together into a homogenous mix |
|
d. |
The time permitted to
manipulate the material within the mouth |
6. Mixing
time
7. Working
time
8. Initial
set time
9. Final
set time
6. ANS:
C
REF: p.
23
TOP: Reaction
7. ANS:
D
REF: p.
24
TOP: Reaction
8. ANS:
A
REF: p.
24
TOP: Reaction
9. ANS:
B
REF: p.
24
TOP: Reaction
SHORT ANSWER
1. List
and describe the three types of primary bonds.
ANS:
·
Ionic bond: A metal gives an electron to an atom that needs
extra electrons.
·
Covalent bond: Occurs when two atoms share electrons in their
outer shell, creating full shells for both.
·
Metallic bond: The electrons in the outer shells are shared
among all the atoms in the lattice with all the atoms positively charged.
REF: p.
20
TOP: Physical Structure (Primary Bonds)
2. List
and describe the three different classifications of dental materials.
ANS:
·
Preventive materials: Directed toward preventing the occurrence
of oral disease and promoting oral health.
·
Therapeutic materials: Used in the treatment of disease and
include materials such as medicated bases or topical treatments for periodontal
disease.
·
Restorative materials: Applies to any filling, inlay, crown,
bridge, implant, or partial or complete denture that restores or replaces lost
tooth structure, teeth, or oral tissue.
REF: p.
23
TOP: Application
Chapter 04: General Handling and Safety of Dental Materials in
the Dental Office
MULTIPLE CHOICE
1. Which
of the following are considered to be personal protective equipment (PPE)?
|
a. |
Protective shields on model
trimmers and on collection bins for lathes |
|
b. |
Dust or surgical masks,
eyewear, gowns, and hair coverings or tiebacks when appropriate |
|
c. |
Surface and immersion
disinfectants |
|
d. |
Plastic wraps and covers |
ANS: B
Dust or surgical masks, eyewear, gowns, and hair coverings or
tiebacks when appropriate are considered to be PPE. During the manipulation of
many dental materials, particulate matter can be generated. It is important for
each person handling and manipulating these materials to have and use the
proper PPE.
REF: p. 28
TOP: Material Hazards in the Dental Environment
(Exposure to Particulate Matter)
2. A
hazardous chemical is any substance that what?
3. Can
catch fire
4. Can
react or explode when mixed with other substances
5. Is
corrosive or toxic
6. May
cause infection or disease
|
a. |
1, 2, 3, 4 |
|
b. |
1, 2, 3 |
|
c. |
2, 3, 4 |
|
d. |
1, 3 |
ANS: B
A hazardous chemical is any substance that can catch fire, can
react or explode when mixed with other substances, or is corrosive or toxic. It
is defined as any chemical that has been shown to cause either a physical or
health hazard. Many dental materials contain more than one chemical.
REF: p.
29
TOP: Chemical Safety in the Dental Office (Hazardous Chemicals)
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