Reversible Hydrocolloid Impression Material

Among the oldest dental impression materials still in use, reversible hydrocolloid impression materials are formulated with agar and effectively solidify from their liquid state to a solid gel state in the mouth to capture a highly accurate impression. These materials are temperature sensitive, changing from liquid to solid at different temperatures, so they are often used with special water-cooled trays in order to capture the most accurate impressions. Because of the reversible nature of these materials, models should be poured immediately after the impression is taken. These materials work well because of their natural hydrophilicity and the fact that the material does not need to be mixed prior to being added to the impression tray. While these materials can be easy to use, it is usually only possible to pour one model per impression, which means reversible hydrocolloids need to be used under proper conditions and models must be created immediately after the impression is captured.