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P2 > LECTURE 13: IMPRESSION MATERIALS AND PROCEDURES FOR RPD > Flashcards

LECTURE 13: IMPRESSION MATERIALS AND PROCEDURES FOR RPD Flashcards

1
Q

capable of recording tooth and tissue details accurately; they
cannot be removed from the mouth without fracture and reassembly

A. Rigid
B. Thermoplastic
C. Elastic

A

A

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2
Q

was once the only material available for partial denture impression, but now elastic materials have replaced them

A. PLASTER OF PARIS
B. METALLIC OXIDE PASTE

A

A

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3
Q

used by many dentists to record maxillomandibular relationship

A. PLASTER OF PARIS
B. METALLIC OXIDE PASTE

A

A

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4
Q

some form of a zinc oxide-eugenol combination

A. PLASTER OF PARIS
B. METALLIC OXIDE PASTE

A

B

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5
Q

not used as primary impression materials and not used for impressions that include remaining natural teeth

A. PLASTER OF PARIS
B. METALLIC OXIDE PASTE

A

B

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6
Q

→ not used in stock tray
→ border molding with _____ is not advisable because wrinkles will occur if movement is permitted at the time of setting

A. PLASTER OF PARIS
B. METALLIC OXIDE PASTE

A

B

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7
Q

have a setting time during which they should
not be disturbed and after which no further border molding is effective

A. PLASTER OF PARIS
B. METALLIC OXIDE PASTE

A

B

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8
Q

are those that become plastic at higher temperature and resume their original form when cooled

A

THERMOPLASTIC IMPRESSION MATERIALS

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9
Q

softened at a temperature above that intended by the manufacturer, the material becomes brittle and unpredictable, also there is the danger of burning the patient’s mouth

A

MODELING PLASTIC (COMPOUND)

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10
Q

modeling plastic forms:

o ___ material in cake form

o ___ modeling plastics in stick form

A

red-brown

red, gray, and green

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11
Q

the most used modeling plastic for corrected impressions of extension base areas for Kennedy Class I and Class II partial denture bases

A. red-brown
B. red, gray, and green

A

A

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12
Q
  1. → used in border molding of impression tray
  2. → ____ have a higher and broader working range
    than do the of cake-like color

A. red-brown
B. red, gray, and green

A
  1. A
  2. red and gray sticks
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13
Q

the modeling plastic are used as a secondary impression
material to record edentulous ridges in partial denture construction; when this is done, it is generally used only as a means of building up the underside of the denture before recording the tissue with secondary impression material

A. red-brown
B. red, gray, and green

A

B

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14
Q

a second group of thermoplastic impression materials consists of those impression waxes and resins commonly spoken of as mouth-temperature waxes

A

IMPRESSION WAXES AND NATURAL RESINS

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15
Q

they are mouth temperature waxes

A

IMPRESSION WAXES AND NATURAL RESINS

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16
Q

T/f

Iowa may be used as a secondary impression material or as impression material for relining

A

T

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17
Q

T/f

since mouth temperature waxes have the ability to flow as long as they are inside the mouth they permit equalization of
pressure and prevent over displacement of tissues

A

T

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18
Q

T/f

IMPRESSION WAXES AND NATURAL RESINS

other type of waxes have more resinous base, they are used to record tissues under an occlusal load

A

T

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19
Q

_____ are not ordinarily used in partial denture
impression technique except for secondary impression for recording partial lower free end

A

resinous waxes

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20
Q

have the ability to flow as long as they are in the mouth and thereby permit equalization of pressure and prevent displacement

A

Impression Wax

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21
Q

may be used to correct the
borders of made of
materials, establishing optimum contact at the border of the denture

A

Impression Wax

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22
Q

→ have the ability to record border detail accurately and include the correct width of the denture border
→ have the advantage of being correctable

A

Impression Wax

23
Q

the principal advantage of mouth temperature waxes is that, given sufficient time, they permit a rebound of those tissues that may have been forcibly displaced

A

Modeling Plastic

24
Q

flow only in proportion to the amount of flaming and tempering that can be done outside of the mouth; this does not continue after the plastic has approached mouth temperature

A

Modeling Plastic

25
Q

T(f

Not all hydrocolloids are dimensionally stable only during a brief period of time

A

F

(all hydrocolloids are dimensionally stable only during a brief period of time)

26
Q

→ hydrophilic materials so can gain water and expand (imbibition), so must not be immersed in water
→ they lose water rapidly and shrink if exposed to air

A

HYDROCOLLOIDS

27
Q

which are fluid at higher temperatures and gel on reduction in temperature, are used primarily as impression materials for fixed restorations

A

reversible (agar-agar) hydrocolloids,

28
Q

used as a removable partial denture impression material

A. REVERSIBLE HYDROCOLLOIDS
B. IRREVERSIBLE HYDROCOLLOIDS

A

REVERSIBLE HYDROCOLLOIDS

29
Q

T/f

because they are made of colloid materials, neither reversible or irreversible hydrocolloid impressions can be stored for any length of time, but must be poured immediately

A

T

30
Q

these materials have low tear strength, provide less surface detail than other materials (e.g., mercaptan rubber base), and are not as dimensionally stable as other materials

A. REVERSIBLE HYDROCOLLOIDS
B. IRREVERSIBLE HYDROCOLLOIDS

A

B

31
Q

→ hydrophilic

A. REVERSIBLE HYDROCOLLOIDS
B. IRREVERSIBLE HYDROCOLLOIDS

A

B

32
Q

the hydrocolloids can be acceptably disinfected with a spray solution of _____, stored in 100% humidity, and poured within 1 hour

A

2% acid glutaraldehyde

33
Q

can be used for RPD impressions especially for altered cast technique or secondary impression

A. reversible
B. irreversible
C. mercaptan rubber
D. polyether impression materials
E. silicone impression materials

A

C

34
Q

→ to be accurate the impression must have a uniform thickness that does not exceed 3 mm

→ materials that are highly cross-linked (medium and heavy body) do not recover well from deformation and should not be used in large multiple undercuts

A. reversible
B. irreversible
C. mercaptan rubber
D. polyether impression materials
E. silicone impression materials

A

C

35
Q

an elastic-type material, as are the polysulfide and silicone materials

A. reversible
B. irreversible
C. mercaptan rubber
D. polyether impression materials
E. silicone impression materials

A

D

36
Q

demonstrate good accuracy in clinical evaluations and are thixotropic, which provides good surface detail and makes them useful as a border molding material

A. reversible
B. irreversible
C. mercaptan rubber
D. polyether impression materials
E. silicone impression materials

A

D

37
Q

flexibility is the lowest of any of the elastic impression materials;
this limits its use in RPD impressions

A. reversible
B. irreversible
C. mercaptan rubber
D. polyether impression materials
E. silicone impression materials

A

D

38
Q

→ stiff material may lead to breakage of cast on removal of cast
from impression

→ unpleasant taste

A. reversible
B. irreversible
C. mercaptan rubber
D. polyether impression materials
E. silicone impression materials

A

D

39
Q

condensation silicones

A. polysiloxanes
B. polyvinyl siloxanes

A

A

40
Q

addition reaction silicones

A. polysiloxanes
B. polyvinyl siloxanes

A

B

41
Q

5-7 minutes working time that can be altered by adjusting the amount of accelerator

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

A

42
Q

→ pleasant odor
→ high tear strength

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

A

(polysiloxanes)

43
Q

should be poured within 1-2 hours

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

A

(polysiloxanes)

44
Q

→ can be poured within up to 1 week

→ thixotropic

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

B

(polyvinyl siloxanes)

45
Q

sulfur in latex gloves and in ferric and aluminum sulfate
retraction solution may inhibit polymerization

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

B

46
Q

→ available in hydrophilic and hydrophobic forms

→ the working time 3-5 minutes can be adjusted with the use of retarders and temperature control

→ hydrophobic; can make cast formation a problem

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

B

47
Q

→ more expensive than other elastic impression materials

→ the most accurate of the elastic impression materials

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

B

48
Q

→ less polymerization shrinkage

→ no smell, no taste

A. CONDENSATION SILICONE IMPRESSION MATERIALS
B. ADDITION SILICONE IMPRESSION MATERIALS

A

B

49
Q

T/f

CONDENSATION SILICONE IMPRESSION MATERIALS and ADDITION SILICONE IMPRESSION MATERIALS has fast recovery from deformation and high tear strength

A

T

50
Q

T/ F

materials that could be permanently deformed by removal from tooth or tissue undercuts should not be used

A

T

51
Q

IMPORTANT PRECAUTIONS TO BE OBSERVED IN THE HANDLING OF HYDROCOLLOID IMPRESSIONS

The impression should be protected from dehydration by
placing it in a humid atmosphere or wrapping it in a damp paper towel until a cast can be poured. To avoid volume change, this should be done within ____ minutes after removal of the impression from the mouth.

A

15

52
Q

_____ from the hydrocolloid has a retarding effect on the chemical reaction of gypsum products and results in a chalky cast surface. This can be prevented by pouring the cast immediately or by first immersing the impression in a solution of accelerator if an accelerator is not included in the formula.

A

Exudate

53
Q

. → the step-by-step procedure and important points to observe in the making of a hydrocolloid impression are as follows:

(1) Select a suitable, sterilized, perforated or rim-lock
impression tray that is large enough to provide a ___ mm thickness of the impression material between the teeth and tissues and the tray.

A

4-5

54
Q

the possible causes of an inaccurate cast are as follows:

A

(1) Distortion of the hydrocolloid impression by:
(a) use of an impression tray that is not rigid
(b) partial dislodgment from the tray
(c) shrinkage caused by dehydration
(d) expansion caused by imbibition (this will be
toward the teeth and will result in an undersized
rather than oversized cast)
(e) attempting to pour the cast with stone that has
already begun to set

(2) A ratio of water to powder that is too high. Although this
may not cause volumetric changes in the size of the cast, it will result in a weak cast.

(3) Improper mixing. This also result in a weak cast or one with a chalky surface.

(4) Trapping of air, either in the mix or in pouring, because of insufficient vibration.

(5) Soft or chalky cast surface that results from the retarding action of the hydrocolloid or the absorption of necessary water for crystallization by the dehydrating hydrocolloid.

(6) Premature separation of the cast from the impression.

(7) Failure to separate the cast from the impression for an
extended period.

P2 (11 decks)

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