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Page 1: 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

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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


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