Which impression material is typically used for fabricating custom trays?

Polysulfide impression material is commonly used for fabricating custom trays due to its excellent properties that make it ideal for this specific application. Polysulfide offers significant flexibility and tear strength, which are crucial characteristics when creating custom trays that need to adapt accurately to the contours of a patient's mouth. This material allows for a precise fit because it can detail the oral structures effectively while still providing enough working time to manipulate it without haste.

Additionally, the stability of polysulfide ensures that the impression remains accurate over time, which is vital when compared to other materials that may not handle the required changes in the oral environment as well. Its dimensional stability helps maintain accuracy, which is crucial for the successful transfer of information to the laboratory for prosthesis fabrication. Thus, using polysulfide for custom trays is favored in prosthetic dentistry.