Deck 13: Polymers in Prosthodontics

Question 1

During denture fabrication,a custom impression tray is typically used to obtain a final impression during the _____ appointment.

A) first
B) second
C) third
D) fourth
E) fifth

Answer 1

second

Question 2

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

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.

Answer 2

Sorption-mediated expansion compensates to some degree for polymerization shrinkage.

Question 3

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

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

Answer 3

unfilled, non-cross

Question 4

Short-term lining materials consist of:

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

Question 5

High degrees of polymerization lead to _____ rigid,_____ soluble polymer networks.

A) more; more
B) less; less
C) more; less
D) less; more

Question 6

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

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

Question 7

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

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

Question 8

Which of the following statements is true of the process of polymerization?

A) Polymerization is a chemical reaction that links small inorganic compounds called monomers into long chains of repeating monomer subunits.
B) Polymers with high degrees of conversion have high levels of residual monomer.
C) Polymers that form by simple addition may not shrink as much as those that form by condensation.
D) Most prosthodontic polymers expand significantly as polymerization proceeds.

Question 9

Cross-linked acrylic polymers are _____ than their non-cross-linked counterparts.

A) less rigid
B) more temperature resistant
C) more soluble
D) A, B, and C
E) A and C

Question 10

When contrasting chemical-cured and heat-cured polymers:

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 11

Removable partial dentures use _____-linked poly(methyl methacrylate)homopolymer.

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

Question 12

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

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 13

The polymerization reaction shrinkage of acrylics approaches _____ vol %.

A) 1
B) 3
C) 6
D) 12

Question 14

When removed from the mouth,dentures:

A) should be boiled and then air dried to kill bacteria and fungi.
B) are best stored in water.
C) should be stored in rubbing alcohol.
D) should be desiccated with acetone to prevent ingress of bacteria.

Question 15

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

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 16

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

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

Question 17

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

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

Question 18

Acrylic polymers used for most dentures:

A) are low in strength.
B) have a high modulus of elasticity.
C) have a low modulus of elasticity.
D) A and B.
E) A and C.

Question 19

Which of the following statements is(are)true of denture soft liners?

A) They may be used for patients with severe undercuts of the edentulous ridges.
B) The hardness of the long-term acrylic materials increases slowly as the plasticizer is leached out by exposure to oral fluids.
C) Silicone liners do not harden as time passes, because they contain no plasticizer.
D) A, B, and C are true statements.
E) A and C are true statements.

Question 20

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

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

Question 21

Copolymers contain two or more different polymers.Copolymers are used in dentures,mouth protectors,and restorative composites.

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 22

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

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

Question 23

The denture base material should be _____ before packing into the flask.

A) doughlike
B) grainy-sandy
C) sticky-stringy
D) viscous-flowing

Question 24

Cross-linked acrylic polymers are:

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

Question 25

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

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 26

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

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 27

Chemical-cured denture materials are initiated using _____ in the monomer liquid that mixes with the benzoyl peroxide in the polymer powder.

A) fillers
B) free-radicals
C) plasticizers
D) accelerators

Question 28

Fillers are particles that are often bonded to the polymer network to:

A) increase strength.
B) reduce water sorption.
C) change the color or transparency.
D) do all of the above.
E) do only A and B.

Question 29

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

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 30

Which of the following statements is correct about plasticizers?

A) Liquid oils such as dibutyl phthalate will cause a PMMA to become rigid.
B) The chemicals in plasticizers do not participate in the polymerization process.
C) The chemicals do not become part of the polymer strands but are trapped in the network.
D) All of the above are correct.
E) Only B and C are correct.

Question 31

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

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

Question 32

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

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

Question 33

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.

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 34

Advantages of light-cured urethane dimethacrylate material versus powder-liquid acrylic material include:

A) lower polymerization shrinkage.
B) lower cost.
C) quicker fabrication time.
D) A, B, and C.
E) A and C.

Question 35

Denture teeth made of acrylic and modified acrylic polymers have replaced ceramic teeth because acrylic teeth:

A) do not wear natural opposing teeth.
B) mechanically bond to the acrylic denture base.
C) better absorb occlusal forces and preserve the edentulous ridge.
D) A, B, and C.
E) A and C.

Question 36

A homopolymer:

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

Question 37

Which of the following statements is correct regarding addition polymerization?

A) It has a high exothermic reaction.
B) It has a low exothermic reaction.
C) It does not create by-products.
D) All of the above are correct.
E) Only A and C are correct.

Question 38

The process of linking monomers into long chains of polymers is known as:

A) poly(methyl methacrylate).
B) polymerization.
C) pickling.
D) PMMA.