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silicon impression Flashcards

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1
Q

Was the first type of silicone impression material used in dentistry

A

CONDENSATION SILICONE

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2
Q

conventional silicones

A

CONDENSATION SILICONE

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3
Q

It is used to get impressions in the preparation of crowns, bridges,
onlays, and inlays.
And also used for an impression in the process of preparation for complete
dentures.

A

CONDENSATION SILICONE

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4
Q

introduced in 1955

A

CONDENSATION SILICONE

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5
Q

It is a type of silicone that forms from a condensation reaction

A

CONDENSATION SILICONE

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6
Q

ADA Specification No. 19

A

Dental Elastomeric Imp. Mat.

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7
Q

Supplied as a base paste and a low-viscosity
liquid catalyst, a two-paste system, or a twoputty system.

A

CONDENSATION SILICONE

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8
Q

Putty is used tray material in conjunction with
a low-viscosity silicone

A

putty-wash
technique

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9
Q

Hydroxyl-terminated polydimethylsiloxane
- undergoes cross-linking to form rubber
Insert filler such as silica, 35-75% (depending on viscosity)
- gives ‘body

A

PASTE (BASE) of condensation silicon

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10
Q

Alkyl silicate (e.g. tetraethyl silicate or orthoethyl silicate)
- acts as a cross-linking agent
Tin compound (e.g. dibutyl tin dilaurate or stannous octoate)
- acts as a reaction catalyst

A

LIQUID (ACCELERATOR) of condensation silicon

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11
Q

Working time of condensation silicon

A

2.5-4 mins

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12
Q

Setting time of condensation silicon

A

6-8 mins

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13
Q
  • GOOD WORKING TIME
  • BETTER ELASTIC PROPERTIES ON REMOVAL –LONG SHELF LIFE
    -CLEAN AND PLEASANT
    -ADEQUATE TEAR STRENGTH
    -EXCELLENT REPRODUCTION
    OF SURFACE DETAILS
A

Advantages of condensation silicon

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14
Q

-GREATER RIGIDITY
-POOR DIMENSIONAL STABILITY
-HYDROPHOBIC
-ALLERGIC REACTIONS
-EXPENSIVE

A

Disadvantages of condensation silicon

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15
Q

An elastomeric impression material of ethylene oxide and tetrahydrofluro copolymers that polymerizes under the influence of an atomic ester

A

POLYETHER

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16
Q

Supplied as a two-paste system in low, medium, and high consistencies.

A

POLYETHER

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17
Q

Commercial names are Impregum, Remitec, Polyjel etc

A

POLYETHER

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18
Q

2 types of polyether

A
  1. .Based on ring
  2. Based on an acid
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19
Q

opening polymerization of aziridine group

A

Based on ring

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20
Q

catalyzed condensation polymerization of
polyether prepolymer with alkoxysilane terminal groups

A

Based on an acid

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21
Q

Polyether - 80 - 85%
Colloidal silica (Filler)
Glycol ether or phthalate (Plasticizer)

A

polyether composition base

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22
Q

Alkyl-aromatic sulfonate (Initiator/crosslinking agent)
Colloidal silica (Filler)
Glycol ether or phthalate (Plasticizer)

A

polyether composition paste

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23
Q

The base paste of a polyether contains polyether
molecules that terminate in an

A

amine group.

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24
Q

Three-membered heterocycle
containing two methylene groups, and the nitrogen
is called an imine.

A

Aziridine rings

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25
main chain of polyether
copolymer of ethylene oxide and tetrahydrofuran.
26
An aromatic sulphonate ester in the activator paste cross-links these polymer chains via the imine end group
Cationic Polymerization
27
Whenever a ring is opened, the cation function remains what? , thus lengthening the chain as the polymers further cross-links.
remains attached
28
Exothermic (polyether)
4-5 degrees Celcius
29
working time of polyether
3 minutes
30
setting time of polyether
6 minutes
31
tear strength of polyether
1800- 4800
32
PERCENT CONTRACTION of polyether
0.19-0.24
33
CONTACT ANGLE BETWEEN SET MATERIAL AND WATER of polyether
49 degrees
34
- GETTING IMPRESSIONS FOR INLAYS AND ONLAYS -DURING PREPARATION FOR CROWNS AND BRIDGES -DURING THE CONSTRUCTION OF -FUNCTIONAL IMPRESSIONS, -CONSTRUCTION OF PARTIAL AND COMPLETE DENTURES -IMPLANT PROSTODONTICS
USES OF POLYETHER
35
manipulation of polyether
- Hand Mixing - Static Mixing - Dynamic Mechanical Mixing
36
Dispense the same lengths of materials onto a mixing pad or glass slab.
Hand Mixing
37
uses a gun for compressing materials in a two-cylinder cartridge.
Static Mixing
38
Uses machine rotating mixers to blend materials as they are extruded through the tip
Dynamic Mechanical Mixing
39
-High level of fidelity -Tear strength -Fast-setting -Clean & easy to use -Least hydrophobic of all elastomers -Margins easily seen -Good stability -Shelf life: 2 yrs
ADVANTAGES OF POLYETHER
40
- stiff, high modulus - unpleasant (bitter) taste and smell - difficult handling - hard rigid material removal from mouth - absorbs water (may suffer expansion) - may cause allergic reaction - high cost
disadvantages of polyether
41
- final impression of full dentures and partial dentures - inlay and crown impressions - fixed bridge impression
common uses of polysulfide
42
mid-1950s
polysulfide
43
made of synthetic rubber and had a long setting time and were not as accurate
polysulfide
44
- first elastomer - homogenous (dentulous) - rubber base - lowest viscosity - least stiff
polysulfide
45
order of impression materials (increasing stiffness)
1. polysulfide 2. condensation silicone 3. addition silicone 4. polyether
46
3 viscosities of polysulfide
1. regular permlastic 2. light bodied permlastic 3. heavy bodied permlastic
47
- partial/full dentures - high degree of flow that will capture all details
regular permlastic
48
- crowns, inlays, and fixed bridged impression - most free flowing - great accuracy and fine definition
light bodied permlastic
49
results in optimum compression of the light bodied permlastic in a double mix
heavy bodied permlastic
50
working time of polysulfide
4-7 mins
51
setting time of polysulfide
7-10 mins
52
tear strength of polysulfide
2500- 7000 gm/cm2
53
dimensional stability of polysulfide
percent contraction .40-.45%
54
loss of polymerization by product
SHRINKAGE
55
lowest cell death count
biocompatibility
56
caused by rocking the material while removal
deformation
57
single swift pull
removal of polysulfide
58
liquid polysulfide polymer - 80-85% inert fillers - 16-18% - titanium oxide, zinc sulfate, silica
base paste of polysulfide
59
lead dioxide - 60-69% dibutyl phthalate - 30- 35% sulfur - 3% other substances - 2% - magnesium stearate and deodorant
catalyst of polysulfide
60
hot and humid will what the setting of polysulfide
accelerate
61
working time at 23 degree of polysulfide
6 mins
62
working time at 37 degree of polysulfide
4.3 mins
63
setting time at 23 degree of polysulfide
16 mins
64
setting time at 37 degree of polysulfide
12.5 mins
65
- long working time - good tear strength/ high tear resistance - good flow before setting - good reproduction of surface detail - high flexibility for easier removal around undercuts - cheaper than silicones and polyether
advantages of polysulfide
66
- unpleasant odor and taste - long setting time - stains clothing (mercaptan) - shrinkage after setting - poor dimension stability - not as accurate as other elastomers
disadvantages of polysulfide
67
Also known as polyvinyl siloxane or vinyl polysiloxane
ADDITION SILICONE
68
most popular elastomeric impressions
ADDITION SILICONE
69
Available as two-paste systems in four viscosities ○ Light ○ Medium ○ Heavy ○ Putty Available in a range of colors
ADDITION SILICONE
70
a polymerization reaction in which each polymer chain grows to a maximal length in sequence
Addition reaction
71
the component that forms the main three-dimensional structure of a final impression
Base Paste
72
a chemical reaction that transforms small molecules into large polymer chains
Polymerization
73
Materials are based on silicone prepolymers with vinyl and hydrogen side groups, which can polymerize by addition polymerization
Composition of addition silicon
74
1. Polymethylhydrosiloxane ○ undergoes cross-linking 2. Divinylpolysiloxane 3. Filler ○ Colloidal silica (35-75%) ○ Controls the viscosity ○ Increasing the filler content increases the consistency of the paste and the stiffness of the impression and decreases the coefficients of thermal expansion and contraction
base of addition silicon
75
Colloidal silica (35-75%) ○ Controls the viscosity ○ Increasing the filler content increases the consistency of the paste and the stiffness of the impression and decreases the coefficients of thermal expansion and contraction
filler (base) of addition silicon
76
Divinylpolysiloxane ○ Cross-linking agent ● Platinum salt ○ Chloroplatinic acid ○ Catalyst ○ Karstedt type ■ complex compound consisting of platinum and 1,3-divinyltetramethyldisiloxane ● Palladium ○ present in some products Hydrogen absorber ● Fillers
catalyst of addition silicone
77
Vinyl siloxane + Hydrogen siloxane --Platinum salt-> Silicone rubber
setting reaction of addition silicone
78
Increases the setting of addition silicone impressions ○ Result of sulfur contamination ○ Retardation or no polymerization in the contaminated area of the impression ● Recommendations ○ Thorough washing of the gloves with detergent and water just before mixing ○ Switching to vinyl and nitrile gloves
Complications with Latex Gloves
79
No reaction by-products are formed, however secondary reaction may produce hydrogen gas which may produced porosity
setting reaction of addition silicone
80
Residual monomer in acrylic provisional restorations and resin composite cores can also inhibit the setting reaction ● Recommendations: use of 2% chlorhexidine to remove contaminants
Other Complications of addition silicone
81
Working time of addition silicone
2- 4 mins
82
setting time of addition silicone
4-6.5 mins
83
- Substitute for alginate impression ● Very precise impression ● High elastic recovery ● High stability ● Low creep ● Multiple usage ● Less irritation ● No unpleasant taste and smell
Advantages of addition silicone
84
-Expensive ● Hydrophobic ● May release hydrogen gas on setting ● Stiff ● Low Tear Strength
Disadvantages of addition silicone

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