Which of the following is one of the primary ingredients in alginate?

The primary ingredient in alginate that is most commonly recognized is sodium alginate. This polysaccharide is derived from brown seaweed and is known for its ability to form a gel when mixed with water and an appropriate salt, often calcium sulfate. Sodium alginate acts as the base that provides the material its properties for dental impressions, allowing it to set and take detailed impressions of oral structures.

In this context, potassium alginate is not the primary ingredient typically used in the formulation of alginate materials for dental applications. While it may be used in some contexts, sodium alginate is the one predominantly associated with dental impressions. Calcium sulfate is often used as a setting agent in the process but is not the main ingredient itself. Silica is used in various dental materials but does not play a role in alginate composition. Thus, the identification of sodium alginate as the primary ingredient is key to understanding the function and application of alginate in dental practices.