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DENT 113 > L4 impression material > Flashcards

L4 impression material Flashcards

1
Q

Impression compound should be soft outside the mouth (___ temp) and gradually hardens in the mouth (lowers to ___ temp)

A

43° - 55°
37.5 - 38°

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2
Q
  • High fusing (soften at 70°C) used as custom tray
  • Used to take final impression
  • SOFT (b27)
  • No longer used in dentistry now due to its bad properties : prone to warping, unstable
A

TYPE II (TRAY COMPOUND)

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3
Q
  • Low fusing (soften at 45°- 55° C) used to record (primary impression and tracing)
  • HARD (b27)
  • Stick form - used for border molding (b27)
A

TYPE I (IMPRESSION COMPOUND)

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4
Q

IMPRESSION CMPD USES

A
  • Primary impression for EDENTULOUS PATIENTS.
  • Modeling or tracing of special acrylic tray
  • Support other impression material (tray for wash
    impression)
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5
Q

different forms of type 1 impression cmpds (4)

A

sheets
sticks
cylinders
cones

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6
Q

type i impression cmpds are capable of recording sharp grooves from ___ wide

A

0.2-4mm

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7
Q

type 1 impression cmpds are _____: Able to record soft tissues under compressed state due to high viscosity

A

mucocompressive material

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8
Q

can be used to extend/line the borders of the tray to copy the shape of the ORAL MUCOSA AND VESTIBULE

A

stick

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9
Q
  • Used for taking impressions of a single tooth
  • A hollow open-ended copper tube is used as a tray
A

COPPER RING TECHNIQUE

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10
Q

causes of warpage: (4)

A
  1. residual stress
  2. incomplete homogenous softening
  3. removal of impression matrial before complete hardenting
  4. delaying in pouring the impression
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11
Q
  • Tray customized for the patient
  • Not used anymore because acrylics and plastics are better and more stable
  • Not distorted at mouth temperature
  • Used for corrective wash impression by adapting soften compound on study model and border of denture area trimmed
  • Tray compound lacks dimensional stability and strength
    thus replaced by acrylics and plastics
A

TYPE II tray compound

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12
Q

viscosity of impression compounds

A

4000 pas (most viscous of impression material)
- 70x > impression plaster
- 100x > light body elastomers

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13
Q

Significance of tray cmpd

A

Limits degree of fine detail which can be recorded in
impression
Characterizes compound as a mucocompressive
impression material

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14
Q

disinfection of tray cmpd

A

immerse for 10mins in 2% alkaline glutaraldehyde solution, rinsed and pour

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15
Q

ada spec of zinc oxide eugenol (ZOE) impression paste

A

16

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16
Q

ZOE can be found in 2 forms of pastes:

A

○ Base (white)
○ Accelerator/Reactor/Catalyst (red)

17
Q

ZOE types of paste

A

type i - soft
type ii - hard

18
Q

[mucostatic/mucocompressive]

  • ZOE
  • Impression plaster
  • Impression paste
A

Mucostatic (Minimal soft tissue displacement)

19
Q

[mucostatic/mucocompressive]

Impression compound

A

Mucocompressive (Squishes soft tissue)

20
Q

classify acc to dental use [complete denture / dentulous mouth]

ZOE
Impression plaster
Impression compound

A

complete denture

21
Q

classify acc to dental use [complete denture / dentulous mouth]

Alginate
Rubber base impression

A

dentulous mouth

22
Q

ELASTOMERIC IMPRESSION MATERIALS

  • AKA RUBBER IMPRESSION MATERIAL
  • Rubber-like polymers that show an elastic behavior at
    the time of load application
A

elastomeric

23
Q

ELASTOMERIC IMPRESSION MATERIALS

  • Long chain of chemical repeating units that attach
    together to form the set mass (polymers)
24
Q

ELASTOMERIC IMPRESSION MATERIALS
- These polymer molecules have weak interactions in between
(_____ what force ____), although they are tied together in 3D
network

A

Van der Wall forces

25
Q

TYPES OF ELASTOMERIC MATERIALS

A
  1. polysulfide (hydrophobic)
  2. silicones
  3. polyether (hydrophilic)
26
Q

[hydrophobic/philic]

ALL impression materials are ____! If indicated
HYDROPHILIC, an ADDITIVE is only added to make it
_____

A

HYDROPHOBIC, PHILIC

27
Q

part of elastomeric impression materials

  • In rubber impression material, after it sets there will ALWAYS be a by-product
  • Material sets via CONDENSATION POLYMERIZATION reaction
  • WATER is the reaction by-product
A

polysulfide rubber

28
Q

polysulfide rubber of elastomeric impression materials

___ is toxic and has bad smell, so it has
been replaced in the recent products by peroxide
compounds

A

lead oxide

29
Q

part of elastomeric impression materials

  • Material sets via CONDENSATION POLYMERIZATION reaction
  • ETHYL ALCOHOL is the reaction by-product
    > Alcohol could cause air bubble in the stone cast
A

condensation silicone

30
Q

Condensation silicone is ____, and can be electroplated with either silver or copper

A

hydrophobic

31
Q

part of elastomeric impression materials:

  • Material sets via ADDITION POLYMERIZATION reaction (no by-product) → more dimensionally stable than condensation polymerized materials
  • HYDROGEN GAS may release from a side reaction in
    presence of moisture or imbalance of reactants
A

additional silicone

32
Q

Additional silicone is ____ and can be electroplated,
however adding of surfactants turns the material ___

A

hydrophobic, hydrophilic

33
Q

part of elastomeric impression materials:

  • Material sets via ADDITION POLYMERIZATION REACTION (NO BY-PRODUCT) → more dimensionally stable than condensation polymerized materials
  • Set material is so STIFF (as a result of high rate of crosslinking), so tray adhesive must be used to retain the material within the tray at the time removing an impression
  • once nagset, mahirap alisin
A

polyether rubber

34
Q

Polyether rubber is ____ and can absorb water in wet
condition (swelling), accordingly.
- Cannot be electroplated
- Should be stored in dry environment to preserve its dimensional accuracy

A

HYDROPHILIC

35
Q

types of tray for elastomeric impression compounds [stock tray/special tray/ wash impression]

  • Used with heavy and putty consistency
  • Retention come through tray perforations, rim locks, or tray adhesive
  • Used to be small, medium, or large only
A

stock tray

36
Q

types of tray for elastomeric impression compounds [stock tray/special tray/ wash impression]

  • Used with light and medium consistency
  • Retention comes from tray perforations and tray adhesive
  • Used in full-dentures
A

special tray

37
Q

types of tray for elastomeric impression compounds [stock tray/special tray/ wash impression]

  • Sometimes heavy or putty impressions act as special tray for light
A

wash impression

38
Q

Which characteristic makes Polyether rubber challenging to
remove from the tray after setting?

A

too stiff due to high cross-linking

39
Q

the elastomeric material has the highest tear strength

DENT 113 (5 decks)

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