Question 1

Short-term lining materials consist of:

Accepted Answer

A)   methacrylate-based polymers.
B)   silicone-based polymers.
C)   polyethylene methacrylate powder and liquid plasticizers.
D)   butadiene-styrene rubber-reinforced polymers. C

Question 2

The extent to which all monomer is polymerized in a polymer is referred to as:

Accepted Answer

A)   threshold level.
B)   degree of conversion.
C)   bond strength.
D)   modulus of elasticity. B

Question 3

The denture base resin mixture should be _____ when it is used to pack the denture flask.

Accepted Answer

A)   grainy
B)   sticky
C)   doughy
D)   rubbery C

Question 4

_____ polymerization uses monomers that have a carbon-carbon double bond as their reactive group.

Accepted Answer

A)   Poly(methyl methacrylate) 
B)   Residual monomer
C)   Free-radical
D)   Addition

Question 5

Orthodontic appliances use _____-linked poly(methyl methacrylate)homopolymer.

Accepted Answer

A)   unfilled, non-cross
B)   unfilled, cross
C)   filled, non-cross
D)   filled, cross

Question 6

Small organic compounds called _____ chemically link into long chains of repeating subunits called _____.

Accepted Answer

A)   polymers; methacrylates
B)   monomers; methacrylates
C)   polymers; monomers
D)   monomers; polymers

Question 7

Not all monomers may be able to participate in the polymerization reaction.Any unreacted residual monomer in the polymer may have significant clinical consequences.

Accepted Answer

A)   Statement 1 is correct; statement 2 is correct.
B)   Statement 1 is correct; statement 2 is incorrect.
C)   Statement 1 is incorrect; statement 2 is correct.
D)   Statement 1 is incorrect; statement 2 is incorrect.

Question 8

Which of the following is the most common type of chemical reaction used to form polymers used for dental restorations?

Accepted Answer

A)   Ring opening to form epoxy polymers
B)   Ring opening to form silicone polymers
C)   Condensation to form silicone polymers
D)   Condensation to form epoxy polymers
E)   Free-radical addition to form acrylic polymers

Question 9

Increased salivary viscosity does not allow good wetting of the denture polymer.Increased salivary viscosity leads to impaired retention of the denture.

Accepted Answer

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.

Question 10

Custom impression trays are essential for the appropriate construction of _____ prostheses.

Accepted Answer

A)   removable but not fixed
B)   fixed but not removable
C)   both removable and fixed
D)   neither removable nor fixed

Question 11

Which of the following is the most common monomer found in acrylic polymers used in dentistry?

Accepted Answer

A)   Methyl methacrylate
B)   Poly(methyl methacrylate) 
C)   Hydroxyethyl methacrylate
D)   Butyl methacrylate
E)   Octyl methacrylate

Question 12

Which of the following statements is(are)true regarding acrylic denture teeth?

Accepted Answer

A)   Polymers in the gingival portion of the plastic teeth have maximal cross-linking to ensure the denture base can bond to the polymer of the denture tooth.
B)   The coronal portion of the tooth is constructed of minimally cross-linked polymer to provide resistance to crazing when the teeth are exposed to solvents during eating.
C)   Cross-linking provides better wear resistance and a more solid feel when the patient chews food.
D)   A, B, and C are true statements.
E)   A and C are true statements.

Question 13

During fabrication of removable partial dentures,the acrylic bonds _____ to the denture teeth and _____ to the alloy framework.

Accepted Answer

A)   chemically; chemically
B)   mechanically; mechanically
C)   chemically; mechanically
D)   mechanically; chemically

Question 14

Which of the following statements is true of Bis-GMA-based polymers used to fabricate temporary crowns or bridges?

Accepted Answer

A)   Lower cost than non-cross-linked acrylic polymers
B)   May be light-cured, chemical-cured, or dual-cured
C)   Do not wear as well as acrylic polymers
D)   Are more difficult to trim than acrylic polymers

Question 15

Soft liners are used for patients with minimal undercuts of the edentulous ridges.They are also used for those patients whose ridges are continually sore.

Accepted Answer

A)   Statement 1 is correct; statement 2 is correct.
B)   Statement 1 is correct; statement 2 is incorrect.
C)   Statement 1 is incorrect; statement 2 is correct.
D)   Statement 1 is incorrect; statement 2 is incorrect.

Question 16

A homopolymer:

Accepted Answer

A)   contains multiple types of monomers.
B)   contains one type of monomer.
C)   contains no monomer.
D)   does not polymerize.

Question 17

Which of the following statements is true concerning denture acrylic polymers and water sorption?

Accepted Answer

A)   Denture acrylic polymers have low water sorption.
B)   Water sorption causes denture expansion of as much as 10%.
C)   Sorption-mediated expansion compensates to some degree for polymerization shrinkage.
D)   Months are necessary for full water sorption to occur.

Question 18

Chemicals such as dibutyl phthalate will cause a poly(methyl methacrylate)to become:

Accepted Answer

A)   greasy.
B)   slippery.
C)   rubbery.
D)   stiff.
E)   porous.

Question 19

When contrasting chemical-cured and heat-cured polymers:

Accepted Answer

A)   residual monomer levels are higher in chemical-cured acrylic polymers.
B)   the clinical fit of heat-cured dentures is somewhat inferior to those cured chemically.
C)   both heat- and chemical-cured acrylic polymers have residual stresses that result from polymerization shrinkage.
D)   A, B, and C.
E)   A and C.

Question 20

Cross-linked acrylic polymers are:

Accepted Answer

A)   more rigid.
B)   more temperature resistant.
C)   less soluble.
D)   all of the above.
E)   only A and B.

Exam 13: Polymers in Prosthodontics