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What is Addition Silicone?
Addition silicone, often shortened to “a-silicone”, is the most used impression material in restorative dentistry. It is widely regarded as the best impression material due to the advantages it holds over alternative materials. Also known as PVS (polyvinyl siloxane) or VPS (vinyl polysiloxane), addition silicone is an elastomeric impression material typically used for creating crowns, bridges, partial dentures and implants. A-silicone can take several different forms but will always follow the same chemical reaction of polymerisation and be presented as either a one-stage or two-stage paste-to-paste system.
How is A-Silicone Used?
An a-silicone impression can be done using either a one-stage or two-stage paste-to-paste technique.
- One-stage impression: Heavy-bodied a-silicone or putty is placed onto an impression tray. A layer of light-bodied a-silicone (wash) is then placed over it or directly onto the relevant teeth or both. The impression tray is then placed back into the patient’s mouth for the material to set.
- Two-stage impression: A putty impression is recorded first, and after it has set it is relined with a thin layer of wash material. Two-stage impressions can be taken with or without a spacer.