1 elastomeric impression materials da 122 dental materials
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Elastomeric Impression Materials
DA 122 Dental Materials
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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 tips
– Base 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)
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Mixing elastomeric impression material
• Objective when mixing elastomeric impression materials is:– To obtain a homogenous mix– To obtain a uniform cure of the mix
– Wear non-latex gloves
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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
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Cartridges
• Light-body cartridge with applicator tip or syringe• Heavy-body cartridge• Extruder gun; one for each cartridge; hand-held or mechanical
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Automatic Mixing
• Mechanical device for mixing cartridges
Ex. MixStar Pentamix
7Putty-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
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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
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Viscosities
• Light-bodied = syringe type– “wash”– Thin body, can flow in and around tooth
structure– Used in syringe or extruder gun and placed
directly on tooth or structures in mouth
• Regular or heavy-bodied = tray type– Thicker– Used to fill tray to make chairside custom tray
which will hold light-bodied material against teeth for better detail
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Polysulfide Impression Material
Common Uses• Final impressions for
dentures and partial dentures
• RATIO:– Equal amounts– Mix to homogeneous
consistency
Characteristics:• Known as “rubber base” or
mercaptan• Unpleasant odor (sulphur)• Long setting time• Stains clothing (mercaptan)• Shrinkage after setting
(disadvantage-lacks dimensional stability)
• Greater strength and tear resistance than colloids
• Flexible
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Polysulfide
Armamentarium• Stiff, narrow
impression spatula• Paper mixing pad• Catalyst and base• 2x2 gauze squares• Adhesive-painted
custom impression tray
• Syringe to apply light-bodied material
Clean-up• 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
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Polysulfide
Times• Mix = 60 seconds• Work = 3-6 minutes• Set = 10 – 20 minutes
in mouth
Appearance• Shiny light blue or chocolate brown• Homogenous end product
COMMON BRAND NAMES:
Permlastic Coe-flex Kerr
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Polysulfide Impression material
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Polyether Impression Material
Common Uses• Final impression for
crowns, bridges, indirect inlays or onlays
• RATIO:– Base : Catalyst– Equal amounts
Special Properties• Accuracy• Stability• Stiff enough to be
used without putty on tray
• Shorter working time
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Polyether Impression Material
Armamentarium• Impression tray
prepared with adhesive
• Narrow, stiff spatula• 6x6 paper mix pad• Base and catalyst• Syringe for application
Clean-up• 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 **
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Polyether Impression Material
Times:• Mix = 30 – 45 seconds
• Work = 2 – 3 minutes
• Set = 6 – 7 minutes in mouth
Appearance• Shiny color
• Common Brand Names: Impregum Polyjel NF (we use)
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Polyether Impression material
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Polyvinylsiloxane Impression Material (also known as addition silicone)Common Uses• Final Impressions:
crowns, bridges, indirect inlays or onlays, implant crowns
• Bite registrations
• RATIO:– equal amounts of base
and catalyst
Special Properties• 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
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Polyvinylsiloxane Impression Material
Armamentarium• Extruder gun with
– Cartridge– Tips
• Adhesive-prepared impression tray (custom or stock)
• Also available in automatic mix machine
Clean-up• 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
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Extruder gun dispenser
• Extruder gun dispenser for impression materials:– Impression material moves plunger
forward to force the:• Base and accelerator from the
individual chambers• Then the pastes move into mixing tip• They blend and exit tip as a uniform
paste
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Polyvinylsiloxane
• Disadvantage of polyvinylsiloxane (also known as silicone)– Expensive– Short shelf life
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Polyvinylsiloxane Impression Material
Times:• Mix = 30 seconds
• Work = 2 minutes
• Set = 5 minutes in mouth
Appearance:• Brightly colored,
shiny, rubbery when set
• Common Brand Names: Take 1 Express President
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Techniques for Polyvinylsiloxane
Wash Technique• Heavy body + light
body
• Heavy body = putty in tray
• Light body=put in syringe