Which impression material should NOT be kept in water for more than one hour?

• A. Polyether
• B. Condensation silicone
• C. Polyvinyl silicone
• D. Agar

Answer: (A)

Polyether impression materials are known for their dimensional stability and excellent detail reproduction, making them popular in dental applications. However, they are also sensitive to moisture. Keeping polyether impressions in water for an extended period, such as more than one hour, can lead to the hydrolysis of the polymer chains. This process may negatively affect the accuracy and integrity of the impression, potentially resulting in deformation or dimensional changes.

In contrast, other impression materials mentioned, like condensation silicone, polyvinyl siloxane, and agar, have different properties regarding water resistance. They may tolerate being kept in water for longer periods without significant changes in their physical and mechanical properties. Understanding the specific handling and storage conditions for each material is crucial for achieving optimal results in dental impressions.