DA 122 Dental Materials. Polysulfide Polyether Polyvinylsiloxane (known as addition silicone) All...
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Transcript of DA 122 Dental Materials. Polysulfide Polyether Polyvinylsiloxane (known as addition silicone) All...
ELASTOMERIC IMPRESSION MATERIALSDA 122 Dental Materials
ELASTOMERIC IMPRESSION MATERIALS Polysulfide Polyether Polyvinylsiloxane (known as addition
silicone)All are supplied as
2-paste systems (tubes): Base + catalyst Automix: Extruder guns (catalyst + base) with
cartridge and mixing tipsBase and Catalyst are mixed to homogeneous
consistency Base = paste in tube, cartridge, or putty Catalyst = paste in tube, cartridge, or liquid in bottle
with dropper (AKA “accelerator”)Self-curing (chemical action)
MIXING ELASTOMERIC IMPRESSION MATERIAL Objective when mixing elastomeric
impression materials is:To obtain a homogenous mixTo obtain a uniform cure of the mix
Wear non-latex gloves
TUBES Base and catalyst tubes Narrow stiff impression spatula Large mix pad (6X6) Syringe for light-body material Adhesive-prepared tray for heavy-body material
CARTRIDGES Light-body cartridge with applicator tip or syringe Heavy-body cartridge Extruder gun; one for each cartridge; hand-held or mechanical
AUTOMATIC MIXING Mechanical device for mixing cartridges
Ex. MixStar Pentamix
PUTTY-POLYVINYL SILOXANEADDITION SILICONE Base = jar or bucket Catalyst = jar or liquid Large mix pad (6X6) Narrow, stiff spatula Non-latex gloves Impression tray
Prepared with adhesive
CURING STAGES Self-cure = polymerization Initial set: includes mix and work time
until material stiffens and you cannot
manipulate it
Final set: in mouth; material goes from elasticity phase into rubber phase
Final cure: takes place from 1 – 24 hours after final set; slight dimensional changes can occur
VISCOSITIES Light-bodied = syringe type
“wash”Thin body, can flow in and around tooth
structureUsed in syringe or extruder gun and placed
directly on tooth or structures in mouth Regular or heavy-bodied = tray type
ThickerUsed to fill tray to make chairside custom
tray which will hold light-bodied material against teeth for better detail
POLYSULFIDE IMPRESSION MATERIAL
Common Uses Special Properties
Final impressions for dentures and partial dentures
RATIO: Equal amounts Mix to
homogeneous consistency
Known as “rubber base” or mercaptan
Unpleasant odor (sulphur)
Long setting time Stains clothing
(mercaptan) Shrinkage after setting Greater strength and
tear resistance than colloids
Flexible
POLYSULFIDE
Armamentarium Clean-up
Stiff, narrow impression spatula
Paper mixing pad Catalyst and base 2x2 gauze squares Adhesive-painted
custom impression tray
Syringe to apply light-bodied material
Orange solvent 2x2 gauze squares Wait until set to peel set
material off spatula Remove used sheet of
mixing pad Recap impression materials
MIX Surface: paper mixing pad
MIX instrument: Stiff, narrow spatula
POLYSULFIDE
Times Appearance
Mix = 60 seconds Work = 3-6 minutes Set = 10 – 20
minutes in mouth
Shiny light blue or chocolate brown Homogenous end
product
COMMON BRAND NAMES:
Permlastic Coe-flex Kerr
POLYSULFIDE IMPRESSION MATERIAL
POLYETHER IMPRESSION MATERIAL
Common Uses Special Properties
Final impression for crowns, bridges, indirect inlays or onlays
RATIO: Base : Catalyst Equal amounts
Accuracy Stability Stiff enough to be
used without putty on tray
Shorter working time
POLYETHER IMPRESSION MATERIAL
Armamentarium Clean-up
Impression tray prepared with adhesive
Narrow, stiff spatula
6x6 paper mix pad Base and catalyst Syringe for
application
Wait until material sets and then peel it off of spatula or other non-porous surfaces
Wipe item clean with rubbing alcohol
MIX surface: paper pad
MIX instrument: Narrow, stiff spatula
**automatic mix units available **
POLYETHER IMPRESSION MATERIAL
Times: Appearance
Mix = 30 – 45 seconds
Work = 2 – 3 minutes
Set = 6 – 7 minutes in mouth
Shiny color
Common Brand Names: Impregum Polyjel NF (we use)
POLYETHER IMPRESSION MATERIAL
POLYVINYLSILOXANE IMPRESSION MATERIAL (ALSO KNOWN AS ADDITION SILICONE)
Common Uses Special Properties
Final Impressions: crowns, bridges, indirect inlays or onlays, implant crowns
Bite registrations
RATIO: equal amounts of
base and catalyst
Available in range of viscosities (“bodies”) or forms: Light, medium, heavy
body Highly accurate Easy to spatulate Odor-free Tends to bubble on
setting Latex gloves may inhibit
set; use vinyl or nitrile gloves
POLYVINYLSILOXANE IMPRESSION MATERIAL
Armamentarium Clean-up
Extruder gun with Cartridge Tips
Adhesive-prepared impression tray (custom or stock)
Also available in automatic mix machine
Immediately on porous surfaces; can stain
Wait to set to peel off non-porous surfaces
Mix surface/instrument: Not necessary
because extruder gun is used
EXTRUDER GUN DISPENSER Extruder gun dispenser for impression materials:Impression material moves plunger forward to force the:Base and accelerator from the
individual chambersThen the pastes move into mixing
tipThey blend and exit tip as a
uniform paste
POLYVINYLSILOXANE Disadvantage of polyvinylsiloxane (also
known as silicone)ExpensiveShort shelf life
POLYVINYLSILOXANE IMPRESSION MATERIAL
Times: Appearance:
Mix = 30 seconds
Work = 2 minutes
Set = 5 minutes in mouth
Brightly colored, shiny, rubbery when set
Common Brand Names: Take 1 Express President
TECHNIQUES FOR POLYVINYLSILOXANE
Wash Technique
Heavy body + light body
Heavy body = putty in tray
Light body=put in syringe