Dental Polymers/Denture Base Resins UPDATED ACTUAL Exam Questions and CORRECT Answers
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Dental Polymers/Denture Base Resins
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Dental Polymers/Denture Base Resins
Dental Polymers/Denture Base Resins
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Which of the following is true regarding addition polymerization?
a.
It occurs in three stages: initiation, margination, and condensation.
b.
Monomers have a core of two silicon atoms joined by a double bo...
Dental Polymers/Denture Base Resins
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Which of the following is true regarding addition polymerization?
a.
It occurs in three stages: initiation, margination, and condensation.
b.
Monomers have a core of two silicon atoms joined by a double bond.
c.
One carbon atom has two hydrogen atoms attached, and the other carbon atom has attached to
it one hydrogen atom and one reactive group called a free radical.
d.
The reaction produces by-products such as water, hydrogen gas, or alcohol that may
compromise the physical properties or handling characteristics. - CORRECT ANSWER✔✔-
ANS: C
One carbon atom has two hydrogen atoms attached, and the other carbon atom has attached to
it one hydrogen atom and one reactive group called a free radical. Addition polymerization
occurs in three stages: initiation, propagation, and termination. Monomers have a core unit of
two carbon atoms joined by a double bond. The condensation polymerization reaction
produces by-products such as water, hydrogen gas, or alcohol that may compromise the
physical properties or handling characteristics.
In an addition polymerization reaction, the free radical initiates the reaction by:
a.
opening the bond between the two carbon atoms of the monomer
b.
creating a bend in the carbon atom
c.
excluding divalent cations
d.
reversing the polarity of the monomer chain - CORRECT ANSWER✔✔- ANS: A
,In an addition polymerization reaction, the free radical initiates the reaction by opening the
bond between the two carbon atoms of the monomer. The broken bond causes the monomer
molecule to bond to another monomer. Each linkage leaves a free radical available for further
reaction.
The monomer will _____________ if the temperature becomes too great during the
polymerization process.
a.
cause crazing of the material
b.
vaporize and produce porosity
c.
bleach the denture white
d.
warp the prosthesis - CORRECT ANSWER✔✔- ANS: B
The monomer will vaporize and produce porosity if the temperature becomes too great during
the polymerization process. Porosity weakens the material, causes it to discolor as stains are
absorbed into the pores, and can lead to retention and growth of oral microorganisms.
The polymerized acrylic resin formed when a liquid monomer is mixed with a powder of
small polymer beads is:
a.
bis-GMA
b.
benzoyl peroxide
c.
poly (ethyl methacrylate)
d.
poly (methyl methacrylate) - CORRECT ANSWER✔✔- ANS: D
The polymerized acrylic resin formed when a liquid monomer is mixed with a powder of
small polymer beads is poly (methyl methacrylate). It is composed of numerous methyl
methacrylate (MMA) monomer units linked together to form a long-chain polymer.
, Which of the following is true regarding the properties of acrylic resins used in dentistry?
a.
Heat-cured acrylic resins shrink about 0.6% by volume.
b.
The coefficient of thermal expansion of acrylic resins is more than twice that of composite
resins.
c.
The strength of acrylic resins is comparable with dental amalgam.
d.
Denture bases conduct temperature very well. - CORRECT ANSWER✔✔- ANS: B
The coefficient of thermal expansion of acrylic resins is more than twice that of composite
resins. Heat-cured acrylic resins shrink about 6% by volume and about 0.2% to 0.5% linearly.
The strength of acrylic resins is fairly low, with a compressive strength of approximately
11,000 psi and a tensile strength of 8000 psi. By comparison, amalgam has a compressive
strength of about 60,000 psi. Denture bases do not conduct temperature well.
In general, the chemical-cured acrylic resins are ____________ than heat-cured acrylic
resins.
1. stronger
2. harder
3. more porous
4. less color stable
a.
1, 2, 3, 4
b.
1, 2, 3
c.
1, 2
d.
3, 4 - CORRECT ANSWER✔✔- ANS: D
In general, the chemical-cured acrylic resins are more porous and less color stable but weaker
and softer than heat-cured acrylic resins. After polymerization, there is more residual
monomer in the chemical-cured acrylic, and this initially adversely affects many of the
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