Australian Dental Council (ADC) Test 2026 – 400 Free Practice Questions to Pass the Exam

When a dry cast is immersed in water saturated with calcium sulphate, it undergoes a process characterized by negligible expansion. This is primarily because the dry cast is already in a stable state and typically contains a limited amount of water. When introduced to water saturated with calcium sulphate, any potential absorption of water by the cast results in only a slight increase in volume, if at all.

In this context, the properties of the materials involved play a crucial role. Calcium sulphate, especially in the form of gypsum, can create a slightly supersaturated solution. However, when a dry cast interacts with such a solution, the solid forms of calcium sulfate do not significantly increase the volume of the cast. The material’s stability and the limited interaction with the saturated solution means that there is minimal change in size or structure, leading to the conclusion of negligible expansion.

The other potential scenarios—contraction, definite expansion, or no change—imply different interactions between the cast and the saturated water, which do not align with the known behavior of dental casts in such a situation. Contraction would suggest a loss of volume, which is not supported by the context of water absorption. Definite expansion implies a significant change in size, contrary to the limited nature of the