Deck 17: Polymers for Prosthetic Dentistry

Question 1

Why do some clinicians place three or four 2-mm-diameter holes in the wax spacer in the anterior and posterior ridge regions?

A) The spacer creates a uniform thickness for impression material.
B) The holes help prevent the wax from separating from the stone model.
C) Placing holes creates a mesh for bonding of acrylic to a metal framework.
D) It helps orient the tissue-bearing side of the tray toward the teeth.

Answer 1

The spacer creates a uniform thickness for impression material.

Question 2

The monomer will _____ if the temperature becomes too great during the polymerization process.

A) vaporize and produce porosity
B) cause crazing of the material
C) bleach the denture white
D) warp the prosthesis

Answer 2

vaporize and produce porosity

Question 3

Which of the following is true of the chairside reline?

A) It utilizes an indirect technique in which an impression of the tissues is made inside the existing denture and a cast is made from this impression.
B) The reline material is applied to the primed denture base,and the denture is reseated in the patient's mouth for border molding.
C) An indexing instrument is used to establish the relationship between the cast and the denture.
D) The lining material is heat- and pressure-processed in the denture base.

Answer 3

The reline material is applied to the primed denture base,and the denture is reseated in the patient's mouth for border molding.

Question 4

Which of the following is true of plastic (acrylic)and porcelain denture teeth?

A) Porcelain teeth are used more often than plastic teeth.
B) Porcelain denture teeth chemically bond to the acrylic base of the denture.
C) Plastic denture teeth do not wear the opposing natural or artificial teeth or restorations.
D) It is easier to grind porcelain denture teeth rather than acrylic denture teeth to adjust the occlusion or to reshape a tooth to fit the available space.

Question 5

A specialized aspect of a/an _____ practice may include the fabrication of maxillofacial prostheses to replace facial tissues lost as the result of trauma,disease,surgery,or birth defect.

A) prosthodontic
B) periodontic
C) endodontic
D) orthodontic

Question 6

What is the polymerized acrylic resin formed when a liquid monomer is mixed with a powder of small polymer beads?

A) BIS-GMA
B) Benzoyl peroxide
C) Poly (ethyl methacrylate)
D) Poly (methyl methacrylate)

Question 7

Which of the following is true regarding the properties of acrylic resins used in dentistry?

A) Denture bases conduct temperature very well.
B) Heat-cured acrylic resins shrink about 0.6% by volume.
C) The strength of acrylic resins is comparable with dental amalgam.
D) The coefficient of thermal expansion of acrylic resins is more than twice that of composite resins.

Question 8

What are record bases used for?

A) To obtain secondary impressions for creation of secondary or master casts
B) To establish the proper dimension between upper and lower arches
C) To obtain final crown and bridge impressions
D) To fabricate porcelain veneers

Question 9

Polymerization of chemical-cured acrylic resins is set into action when the tertiary amine in the liquid activates the _____ in the powder to produce free radicals.

A) plasticizers
B) hydroquinone
C) benzoyl peroxide
D) glycol dimethacrylate

Question 10

During processing of a denture base,heat-cured acrylic resin in the _____ stage is placed in the space created by removal of the wax and record base.

A) sandy
B) sticky
C) dough
D) rubber

Question 11

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.

Question 12

When the acrylic powder and liquid are mixed,the chemical- and heat-cured materials go through a similar reaction,except that chemical-cured materials have a _____ in the liquid as an activator,whereas heat-cured materials do not.

A) benzoyl peroxide
B) hydroquinone
C) glycol dimethacrylate
D) tertiary amine

Question 13

Which of the following laboratory devices helps keep the monomer from evaporating during polymerization and creates a denser acrylic?

A) Lathe
B) Pressure pot
C) Bunsen burner
D) Vacuum-forming machine

Question 14

Which of the following is true of long-term soft liners for complete and partial dentures?

A) Silicone long-term liners are less stable over the long term than acrylic long-term liners because they have softeners that leach out.
B) Long-term liners may not be processed with the application of heat.
C) Long-term soft liners often do not form a good bond to old acrylic.
D) Silicone liners are easy to adjust.

Question 15

In an addition polymerization reaction,the free radical initiates what reaction?

A) Opening the bond between the two carbon atoms of the monomer
B) Reversing the polarity of the monomer chain
C) Creating a bend in the carbon atom
D) Excluding divalent cations

Question 16

Which of the following is the correct sequence to prepare a broken denture for denture repair with chemical-cured acrylic repair material?
1)Place a coating of the liquid monomer on the roughened surface to wet and prime them.
2)Pour plaster or stone in the prosthesis to create a cast on which to stabilize the parts while they are being repaired.
3)Piece the broken pieces together with sticky wax.
4)Cut the fracture line with an acrylic bur.

A) 1,3,2,4
B) 2,1,4,3
C) 3,2,1,4
D) 3,2,4,1

Question 17

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

Question 18

Polymerization shrinkage is seen most readily in which of the following areas of a heat-cured acrylic resin denture?

A) Labial flange
B) Alveolar ridge
C) Palatal
D) Hamular notch

Question 19

Which of the following correctly represents the stages seen when acrylic powder and liquid are mixed together?

A) Dough,sandy,rubber,and stringy
B) Stringy,sandy,dough,and rubber
C) Sandy,stringy,dough,and rubber
D) Rubber,stringy,dough,and sandy

Question 20

Which of the following is true of in-office care of a complete denture?

A) Patients will not form calculus on a denture.
B) Tissue-bearing surfaces of the complete denture should be polished during cleaning.
C) It is helpful for the patient if teeth and the acrylic base are worn down during the polishing process.
D) Calculus can be removed by placing the prosthesis in a denture cleaning solution inside a zippered bag placed in an ultrasonic cleaner.

Question 21

How are dentures customized?

A) Recreating diastemas
B) Placing restorations in the acrylic teeth
C) Changing acrylic shades to match skin tone
D) All of the above are possible.

Question 22

Sources of dimensional change for polymeric materials include which of the following?

A) Coefficient of thermal expansion
B) Accelerators and inhibitors
C) Thermal conductivity
D) Water sorption

Question 23

Match the items with the correct description below.
Polymerization

A)A long-chain,high-molecular-weight molecule produced by the linking of many low-molecular-weight monomer molecules
B)A polymer composed of numerous methyl methacrylate monomers linked together in a long chain
C)The joining of adjacent long-chain polymers by bonding of short chains along their sides
D)The act of forming polymers.The process can be activated by chemicals,heat,or light.
E)Low-molecular-weight molecules that are joined to form polymers

Question 24

What are denture teeth usually made of?

A) Plastic
B) Porcelain
C) Composite resin
D) Any of the above

Question 25

The most common form of polymerization in dentistry is:

A) tertiary.
B) addition.
C) propagation.
D) condensation.

Question 26

Which of the following does not apply to porcelain denture teeth?

A) They are hard.
B) They are esthetic.
C) They are easily repaired.
D) They are stain resistant.

Question 27

Describe the process of addition polymerization.

Question 28

Match the items with the correct description below.
Monomer

A)A long-chain,high-molecular-weight molecule produced by the linking of many low-molecular-weight monomer molecules
B)A polymer composed of numerous methyl methacrylate monomers linked together in a long chain
C)The joining of adjacent long-chain polymers by bonding of short chains along their sides
D)The act of forming polymers.The process can be activated by chemicals,heat,or light.
E)Low-molecular-weight molecules that are joined to form polymers

Question 29

Which of the following is true about polymers?

A) They are large,long-chain molecules.
B) They are small,long-chain molecules.
C) They are large,short-chain molecules.
D) They are small,short-chain molecules.

Question 30

Home care of dentures would not include which of the following?

A) Soaking in mouthwash to remove odors
B) Brushing with a denture brush after meals
C) Using a denture toothpaste to remove plaque
D) Soaking in white vinegar to remove calculus

Question 31

Match the items with the correct description below.
Poly (methyl methacrylate)

A)A long-chain,high-molecular-weight molecule produced by the linking of many low-molecular-weight monomer molecules
B)A polymer composed of numerous methyl methacrylate monomers linked together in a long chain
C)The joining of adjacent long-chain polymers by bonding of short chains along their sides
D)The act of forming polymers.The process can be activated by chemicals,heat,or light.
E)Low-molecular-weight molecules that are joined to form polymers

Question 32

Match the items with the correct description below.
Cross-linked polymers

A)A long-chain,high-molecular-weight molecule produced by the linking of many low-molecular-weight monomer molecules
B)A polymer composed of numerous methyl methacrylate monomers linked together in a long chain
C)The joining of adjacent long-chain polymers by bonding of short chains along their sides
D)The act of forming polymers.The process can be activated by chemicals,heat,or light.
E)Low-molecular-weight molecules that are joined to form polymers

Question 33

Match the items with the correct description below.
Polymer

A)A long-chain,high-molecular-weight molecule produced by the linking of many low-molecular-weight monomer molecules
B)A polymer composed of numerous methyl methacrylate monomers linked together in a long chain
C)The joining of adjacent long-chain polymers by bonding of short chains along their sides
D)The act of forming polymers.The process can be activated by chemicals,heat,or light.
E)Low-molecular-weight molecules that are joined to form polymers

Question 34

Which of the following is not true about cross-linked polymers?

A) The bonds are weak.
B) The bond is stronger and stiffer.
C) They have short chain atoms attached.
D) The material is not easily manipulated.

Question 35

Why must dentures be relined periodically?

A) Dentures absorb odors from plaque and food.
B) Dimensional changes in acrylic occur.
C) Alveolar ridges shrink over time.

Question 36

What is the result of the loss of monomer or inadequate pressure during processing?

A) A brittle material
B) Shrinkage of the material
C) Porosities in the material
D) Discoloration of the material

Question 37

Describe how a denture is fabricated using heat-cured resin.