Which impression material type is less flowable at body temperature?

The impression material type that is less flowable at body temperature is classified as Type I. This type is typically designed for specific applications, particularly for making impressions where higher viscosity is necessary to minimize distortion or movement during the impression-taking process.

The flow characteristics of impression materials are critical as they dictate how well the material can capture fine details of the oral structures. Type I materials are generally formulated to be more rigid and have lower flow characteristics at body temperature, which is advantageous in providing stability once the impression is set.

In contrast, Type II, Type III, and Type IV materials are designed to have varying degrees of flowability and are often used for different purposes. For instance, Type II materials may be more flowable, allowing for better capture of finer details in less rigid scenarios, whereas Type III and Type IV materials typically offer variations in elasticity and setting times suitable for other specific applications, including functional or more complex restorative procedures.

In summary, Type I's reduced flowability at body temperature makes it ideal for situations where dimensional stability and detail retention are critical, thus making it the correct choice for this question.