Condensation silicones

Choosing Condensation Silicone Impression Materials

• Condensation vs Addition Silicone — Condensation silicones are less dimensionally stable than addition (polyvinyl siloxane) silicones due to by-product shrinkage during polymerisation. For indirect restorations requiring high precision (CAD/CAM, implants), addition silicone is preferred; condensation silicone suits routine crown and bridge work at lower cost.
• Putty Viscosity — Putty condensation silicone is used in the stock tray as the bulk impression material; the putty registers gross anatomy and holds the wash in place. Mix putty base and catalyst in equal volumes (by ratio) until colour is uniform -- undermixing creates sticky, weak areas in the final impression.
• Wash (Light-Body) Viscosity — Light-body condensation silicone is syringe-applied directly to the prepared tooth to capture fine margin detail before the putty is seated. Inject wash from apical to coronal to prevent air traps; seat the putty-loaded tray within 30 seconds of wash injection.
• Putty-Wash Technique — The putty-wash technique achieves the best margin detail by using putty for bulk support and wash for fine surface recording. One-step vs two-step putty-wash: two-step (putty first, then wash) gives more wash space and better detail but requires a second appointment or re-insertion step.
• Dimensional Stability — Condensation silicone impressions must be poured within 30-60 minutes of removal from the mouth due to continued by-product shrinkage. Never store unpoured condensation silicone impressions -- shrinkage of 0.5-1% over 24 hours causes crown margin discrepancies visible clinically.
• Shelf Life and Storage — Condensation silicone has a 2-year shelf life when stored below 25 deg C -- Egypt's climate requires refrigerated storage or climate-controlled rooms. High ambient temperatures accelerate polymerisation catalyst degradation -- check setting time on first use from a new batch to detect accelerated aging.

Impression Material Types at a Glance

How to Take a Putty-Wash Condensation Silicone Impression

1. Mix equal volumes of putty base and catalyst until colour is fully uniform (60-90 seconds).
2. Load a stock tray with putty and prepare the wash syringe simultaneously.
3. Dry the prepared tooth and inject light-body wash from below the margin to the occlusal surface.
4. Seat the putty-loaded tray within 30 seconds of wash injection and hold steady for the full setting time.
5. Remove in a single snap motion; pour the impression in dental stone within 30-60 minutes.

Availability & Delivery in Egypt

MedSTA supplies condensation silicone impression materials to Egyptian dental clinics and labs with EGP pricing and nationwide delivery. Store in climate-controlled conditions to maintain shelf life in Egypt's climate.