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