HOSA Dental Terminology Practice

Which of the following materials is characterized as nonelastic when used for impressions?

1. Alginate

2. Compound

3. Silicone

4. PVA

The correct answer is: Compound

The correct response to the question about which impression material is characterized as nonelastic is compound. Compound materials, often used in dental impressions, are thermoplastic substances that do not have the ability to deform elastically after setting; once they cool and solidify to capture a dental impression, they do not return to their original shape. This characteristic makes them suitable for making accurate impressions in certain situations where precision is required. In contrast, alginate is an elastic impression material frequently used for making preliminary impressions, as it can stretch and return to its original shape, allowing for a more flexible capturing of the anatomy. Silicone is another elastic material, known for its dimensional stability and flexibility, making it favorable for detailed impressions. PVA (polyvinyl acetate) typically has elastic properties as well and is not known for being nonelastic. Understanding these materials' properties helps in choosing the right type for specific dental procedures.