At elevated temperatures, which type of impression material changes from a gel to a sol?

Reversible hydrocolloid is a unique impression material that undergoes a transformation between its gel and sol states with temperature changes. When heated, reversible hydrocolloid becomes a sol (a more fluid state), allowing it to flow easily into the impression tray and adapt to the details of the oral structures being captured. As it cools, the sol transitions back to a gel state, solidifying to form a stable impression.

This thermoreversible property is fundamental to the function of reversible hydrocolloids in dentistry, as it allows for easy manipulation during the impression process. This distinguishes it from other impression materials, which do not exhibit such a direct phase change in response to temperature. Polysulfide polymer and addition silicone materials, for instance, do not change state in this manner; instead, they set through a chemical reaction. Polyether materials also do not exhibit the gel-to-sol transition of reversible hydrocolloids when temperature increases.

Understanding this phase change is essential for utilizing reversible hydrocolloid effectively in clinical scenarios, particularly when precise impressions are required.