Elastomeric Impression Materials

1. Elastomeric Impression Materials DA 122 Dental Materials

2. 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)

3. 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

4. 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

5. Cartridges • Light-body cartridge with applicator tip or syringe • Heavy-body cartridge • Extruder gun; one for each cartridge; hand-held or mechanical

6. Automatic Mixing • Mechanical device for mixing cartridges Ex. MixStar Pentamix

7. 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

8. 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

9. 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

10. Polysulfide Impression Material Common Uses 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 • Final impressions for dentures and partial dentures • RATIO: • Equal amounts • Mix to homogeneous consistency

11. Polysulfide Armamentarium 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 • Stiff, narrow impression spatula • Paper mixing pad • Catalyst and base • 2x2 gauze squares • Adhesive-painted custom impression tray • Syringe to apply light-bodied material

12. Polysulfide Times Appearance Shiny light blue or chocolate brown Homogenous end product COMMON BRAND NAMES: Permlastic Coe-flex Kerr • Mix = 60 seconds • Work = 3-6 minutes • Set = 10 – 20 minutes in mouth

13. Polysulfide Impression material

14. Polyether Impression Material Common Uses Special Properties Accuracy Stability Stiff enough to be used without putty on tray Shorter working time • Final impression for crowns, bridges, indirect inlays or onlays • RATIO: • Base : Catalyst • Equal amounts

15. Polyether Impression Material Armamentarium 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 ** • Impression tray prepared with adhesive • Narrow, stiff spatula • 6x6 paper mix pad • Base and catalyst • Syringe for application

16. Polyether Impression Material Times: Appearance Shiny color Common Brand Names: Impregum Polyjel NF (we use) • Mix = 30 – 45 seconds • Work = 2 – 3 minutes • Set = 6 – 7 minutes in mouth

17. Polyether Impression material

18. Polyvinylsiloxane Impression Material (also known as addition silicone) Common Uses 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 • Final Impressions: crowns, bridges, indirect inlays or onlays, implant crowns • Bite registrations • RATIO: • equal amounts of base and catalyst

19. Polyvinylsiloxane Impression Material Armamentarium 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 • Extruder gun with • Cartridge • Tips • Adhesive-prepared impression tray (custom or stock) • Also available in automatic mix machine

20. 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

21. Polyvinylsiloxane • Disadvantage of polyvinylsiloxane (also known as silicone) • Expensive • Short shelf life

22. Polyvinylsiloxane Impression Material Times: Appearance: Brightly colored, shiny, rubbery when set Common Brand Names: Take 1 Express President • Mix = 30 seconds • Work = 2 minutes • Set = 5 minutes in mouth

23. Techniques for Polyvinylsiloxane Wash Technique • Heavy body + light body • Heavy body = putty in tray • Light body=put in syringe