HESI General Chairside Assisting Practice Exam

Which type of gypsum is most suitable for creating a strong bleaching tray?

1. Plaster of Paris

2. Dental Stone

3. Model stone

4. Investment stone

The correct answer is: Dental Stone

Dental Stone is the most suitable type of gypsum for creating a strong bleaching tray due to its superior strength and durability compared to the other types of gypsum. It has a finer particle size and a denser consistency, which translates into better resistance to deformation. This quality is crucial when fabricating trays that must maintain their shape under the pressure of bleaching materials and fit securely in the patient's mouth. Plaster of Paris, while useful in some applications, is typically too soft and brittle for this purpose. It may easily break or warp, compromising the integrity of the bleaching tray. Model stone, although stronger than plaster, does not offer the same level of durability and precision required for the specific fit and function of a bleaching tray. Investment stone, commonly used for castings in dental applications, provides high strength but is usually more rigid and not specifically designed for the flexible, adaptable requirements of a bleaching tray. Therefore, Dental Stone stands out as the most appropriate choice, offering the right balance of strength, durability, and adaptability for this specific dental application.