Deck 14: Impression Materials

Question 1

_______ gloves should be used when mixing PVS putty.

A) Utility
B) Nitrile
C) Latex
D) Vinyl

Answer 1

Vinyl

Question 2

Containers of alginate such as cans or plastic containers should be turned end-over-end a few times to decompress the powder and mix the ingredients. Alginate dust is potentially hazardous to inhale because it contains silicon dioxide in the diatomaceous earth fillers.

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.

Answer 2

Both statements are true.

Question 3

The temperature at which the hydrocolloid liquefies is not the same temperature at which it solidifies, a property called:

A) agglutination
B) hysteresis
C) hydrophilic
D) hydrophobic

Answer 3

hysteresis

Question 4

A properly extended maxillary alginate impression tray will extend posteriorly enough to include the:

A) hamular notch
B) retromolar pad
C) soft palate
D) uvula

Question 5

Which of the following is true for alginate hydrocolloid?

A) Fast-set alginate has a working time of 2 to 3 minutes.
B) Adjusting the powder-to-water ratio is the best way to lengthen or shorten the setting time.
C) Alginate hydrocolloid should be removed slowly to prevent deformation of critical surfaces.
D) Some moisture will be lost from the impression even in 100% humidity.

Question 6

Ideally, an alginate impression should be poured within:

A) an hour
B) a day
C) a week
D) a month

Question 7

Impressions taken with polyvinyl siloxane should be poured within:

A) 30 minutes
B) 1 hour
C) 1 day
D) 1 week

Question 8

Some practitioners use a specially formulated addition silicone material in an automatic mixing cartridge system to make dies for:

A) direct composite inlays
B) indirect composite inlays
C) porcelain jacket crowns
D) porcelain-fused-to-metal crowns

Question 9

For a maxillary alginate impression, the operator stands just ___________________ and retracts the corner of the mouth with the side of the tray while retracting the other corner of the mouth with the index finger of the other hand.

A) in front of the patient at the 5 o'clock position
B) in front of the patient at the 7 o'clock position
C) behind the patient at the 1 o'clock position
D) behind the patient at the 11 o'clock position

Question 10

Mixed alginate should be loaded into the impression tray in _______ increments as ________ as possible.

A) large; quickly
B) large; slowly
C) small; quickly
D) small; slowly

Question 11

Which of the following impression materials has the smallest dimensional change on setting of all elastomeric and hydrocolloid impression materials?

A) Polyether
B) Polysulfide
C) Addition silicone
D) Condensation silicone

Question 12

Which of the following is true of impression trays?

A) Stock trays are made of plastic rather than metal and can be solid or perforated.
B) Plastic trays are inexpensive and are disposable, whereas metal trays are more expensive and must be cleaned and sterilized between uses.
C) Custom trays are constructed in the patient's mouth with chemically cured, light-cured, or thermoplastic resins on casts of the teeth.
D) The triple tray is a custom full-arch tray used for bite registration.

Question 13

Which of the following is true for hydrocolloids in dentistry?

A) Agar hydrocolloid is a reversible hydrocolloid.
B) When agar powder is mixed with water, it forms a glue-like suspension that entraps the water, making a colloidal suspension called a gel.
C) The main clinical use of reversible hydrocolloid is for impressions for diagnostic casts.
D) Agar hydrocolloid requires the use of custom impression trays.

Question 14

The completed impression forms a _____________ reproduction of the teeth and tissues, and the replica or model forms a _________ replica of the teeth and tissues.

A) positive; positive
B) positive; negative
C) negative; positive
D) negative; negative

Question 15

Which of the following is an elastic impression material?

A) Dental impression compound
B) Impression plaster
C) Impression wax
D) Vinyl polyether silicone

Question 16

A vast majority of dies are made from:

A) epoxy
B) metal
C) gypsum
D) wax

Question 17

Which of the following elastomers is the most hydrophilic?

A) Polysulfides
B) Polyethers
C) Condensation silicones
D) Addition silicones

Question 18

Impressions taken with polyether should be poured within:

A) 30 minutes
B) 1 hour
C) 1 day
D) 1 week

Question 19

Which of the following is the most widely used dental impression material?

A) Reversible hydrocolloid
B) Irreversible hydrocolloid
C) Addition silicone impression material
D) Condensation silicone impression material

Question 20

Which of the following is true of vinyl polyether silicone?

A) It is hydrophobic.
B) It can tolerate a little moisture around the preparation.
C) It flows well but has low tear strength.
D) It is available in three viscosities: light, monophase, and heavy.

Question 21

Casts made from improperly disinfected restorations:

A) will not harbor microorganisms
B) should be immersed in solution
C) should be stored for 24 hours first
D) cannot be disinfected, so start over

Question 22

Alginate impressions are used routinely for all of the following except:

A) mouth guard
B) bleaching tray
C) onlay
D) retainer

Question 23

Impressions should be disinfected:

A) for an hour before pouring in gypsum
B) at the dental lab check-in
C) before rinsing with water
D) at the chairside upon removal

Question 24

Match the items with the correct description below.
Irreversible hydrocolloid

A)An alginate impression material that is mixed to a sol state and as it sets converts to a gel by a chemical reaction that irreversibly changes its nature
B)Glue-like material composed of two or more substances in which one substance does not go into solution but is suspended within another substance
C)An agar impression material that can be heated to change from a gel into a fluid state that can flow around the teeth
D)A water-based colloid used as an elastic impression material
E)A versatile irreversible hydrocolloid that is the most used impression material in the dental office

Question 25

Match the items with the correct description below.
Reversible hydrocolloid

A)An alginate impression material that is mixed to a sol state and as it sets converts to a gel by a chemical reaction that irreversibly changes its nature
B)Glue-like material composed of two or more substances in which one substance does not go into solution but is suspended within another substance
C)An agar impression material that can be heated to change from a gel into a fluid state that can flow around the teeth
D)A water-based colloid used as an elastic impression material
E)A versatile irreversible hydrocolloid that is the most used impression material in the dental office

Question 26

List and describe the different types of impression materials suitable for crown and bridge procedures.

Question 27

When mixing alginate, as the water temperature increases, the working time:

A) increases
B) decreases
C) stays the same

Question 28

Match the items with the correct description below.
Alginate

A)An alginate impression material that is mixed to a sol state and as it sets converts to a gel by a chemical reaction that irreversibly changes its nature
B)Glue-like material composed of two or more substances in which one substance does not go into solution but is suspended within another substance
C)An agar impression material that can be heated to change from a gel into a fluid state that can flow around the teeth
D)A water-based colloid used as an elastic impression material
E)A versatile irreversible hydrocolloid that is the most used impression material in the dental office

Question 29

Match the items with the correct description below.
Colloid

A)An alginate impression material that is mixed to a sol state and as it sets converts to a gel by a chemical reaction that irreversibly changes its nature
B)Glue-like material composed of two or more substances in which one substance does not go into solution but is suspended within another substance
C)An agar impression material that can be heated to change from a gel into a fluid state that can flow around the teeth
D)A water-based colloid used as an elastic impression material
E)A versatile irreversible hydrocolloid that is the most used impression material in the dental office

Question 30

When an impression tray is chosen, it should:

A) be large enough to fit all oral structures
B) be rigid to support the impression material
C) accurately reproduce vestibules
D) All of the above are considered.

Question 31

A dentist might choose to use an addition silicone over a condensation silicone because:

A) addition is stronger than condensation
B) addition is cleaner to use
C) addition does not distort as badly
D) addition tastes better

Question 32

A dental impression is a/an _______ reproduction of the teeth.

A) positive
B) negative
C) approximate
D) distorted

Question 33

When preparing to take an alginate impression, which of the following is not necessary?

A) Fluff the material to mix.
B) Wear a mask and eyewear.
C) Have patient use antibacterial rinse.
D) Use a try-in tray for fit.

Question 34

Match the items with the correct description below.
Hydrocolloid

A)An alginate impression material that is mixed to a sol state and as it sets converts to a gel by a chemical reaction that irreversibly changes its nature
B)Glue-like material composed of two or more substances in which one substance does not go into solution but is suspended within another substance
C)An agar impression material that can be heated to change from a gel into a fluid state that can flow around the teeth
D)A water-based colloid used as an elastic impression material
E)A versatile irreversible hydrocolloid that is the most used impression material in the dental office