National Dental Assisting Examining Board (NDAEB) Practice Exam

Which impression material is best suited for creating a diagnostic model?

1. Polyvinyl Siloxane

2. Alginate

3. Silicone

4. Rubber Base

The correct answer is: Alginate

Alginate is considered the best impression material for creating diagnostic models due to its unique properties. It is a irreversible hydrocolloid that is easy to manipulate and provides a good balance between fluidity and viscosity, allowing it to capture fine details of the oral structures effectively. Alginate impressions set quickly, making the process efficient for the dental office setting, and are typically less expensive than other impression materials. Additionally, alginate is well suited for diagnostic models because it is sufficiently accurate for studying the overall and detailed anatomy of a tooth and soft tissue. The resulting models are often used for treatment planning, making preliminary casts, and for educational purposes. In contrast, while other materials like polyvinyl siloxane and silicone can offer high accuracy and detail, they are generally more expensive and are often preferred for final impressions used in restorations, rather than for creating preliminary diagnostic models. Rubber base materials are primarily used for specific applications, such as crown and bridge impressions, and might not be as versatile for routine diagnostic purposes.