What is the name of the elastic irreversible impression material commonly used in dental impressions?

Alginate is the correct answer because it is a type of elastic, irreversible hydrocolloid impression material that is widely used in dental practices for making impressions of teeth and oral structures. Alginate is favored because it is easy to mix and use, sets quickly, and provides a good detail reproduction of the dental anatomy. It is particularly well-suited for preliminary impressions, study models, and in situations where a quick reproduction of oral structures is needed.

Silicone, while also used in dental impressions, is not categorized as an irreversible material. Silicone impressions can be reversible and are often used for high-precision applications due to their superior detail capture and dimensional stability.

Polyether is another type of elastic impression material that is known for its excellent accuracy and detail. However, it is not considered irreversible because it can be removed and reformulated, unlike alginate, which sets chemically and cannot be returned to its original state.

Gypsum, on the other hand, is a material primarily used for creating models and casts after an impression has been taken. It is not an impression material itself but rather a material used to pour into an impression to create a physical reproduction of the dental structures.

Thus, alginate stands out as the best choice for a material that is elastic