Which material is typically used for a preliminary impression for a full denture?

The material that is typically used for a preliminary impression for a full denture is irreversible hydrocolloid, commonly known as alginate. This material is favored for its ease of use, comfortable application, and ability to capture detailed impressions of soft and hard tissues in the mouth.

Irreversible hydrocolloid provides a quick setting time and is capable of reproducing fine detail, making it suitable for preliminary impressions where the goal is to create a mold for initial evaluations. It is also easy to mix and manipulate, which allows practitioners to work efficiently when obtaining impressions from a patient.

Furthermore, alginate impressions can be used to make study casts, which are essential in prosthodontics. However, its dimensional stability is limited compared to other materials, meaning it should not be stored for extended periods before making a final impression. Despite this limitation, its properties make it ideal for quick, preliminary impressions in denture fabrication.