Polyvinyl siloxane
Polyvinyl siloxane (PVS), also called poly-vinyl siloxane, vinyl polysiloxane, or vinylpolysiloxane, is an addition-reaction silicone elastomer (an addition silicone). It is a viscous liquid that cures ("dries") quickly into a rubber-like solid, taking the shape of whatever surface it was lying against while curing. As with 2-part epoxy, its package keeps its 2 component liquids in separate tubes until the moment they are mixed and applied, because once mixed, they cure (harden) rapidly. Polyvinyl siloxane is widely used in dentistry as an impression material.[1] It is also used in other contexts where an impression similar to a dental impression is needed, such as in audiology (to take ear impressions for fitting custom hearing protection or hearing aids[2]) or in industrial applications (such as to aid in the inspection of interior features of machined parts, for example, internal grooves inside bores). Polyvinyl siloxane was commercially introduced in the 1970s.
To create the material, the user simply mixes a colored putty (often blue or pink) with a white putty (both of roughly Play-Doh consistency), and the chemical reaction begins; from that point, it takes approximately 3 to 5 minutes before the final set, so there is limited timeframe in which to apply the material and spread it where it is needed. Final set is noted when the product rebounds upon touching with a blunt or sharp instrument.
This reaction also gives off hydrogen gas and therefore the ensuing cast should wait to be poured at least 5 minutes.
In dentistry, this material is commonly referred to as having light or heavy body depending on specific usage.
See also
References
- ↑ Mandikos M. Polyvinyl siloxane impression materials: An update on clinical use. Australian Dental Journal 1998;43:(6):428-34 Page accessed March 14, 2007.
- ↑ | Audiology Ear Mold Impression Material