DANB General Chairside Practice Test

What effect does a cooler, less humid treatment room have on impression materials?

1. Decreased working time

2. Increased setting times

3. Improved accuracy

4. Faster curing times

The correct answer is: Increased setting times

A cooler, less humid treatment room significantly affects the properties of impression materials, particularly regarding their setting times. When the ambient temperature is lower, the chemical reactions involved in the setting process may occur more slowly. This is due to the fact that most impression materials, such as alginates and polyvinyl siloxanes, are influenced by temperature: they generally cure more slowly in cooler conditions. As a result, when the setting time is increased, clinicians have more time to work with the material, allowing for better manipulation and placement, which can lead to improved impressions. While accuracy is important and can be affected by the environment, the direct relationship of cooler temperatures causing longer setting times is most evident. Thus, the effects on working time, curing times, and potentially altered material properties become secondary to the clear understanding that lower temperatures lead to an increase in the time required for the materials to set fully.