Which of the following materials is NOT typically included in a resin composition?

The material that is not typically included in a resin composition is calcium hydroxide. Resin compositions commonly consist of components that facilitate polymerization and enhance their adhesive properties.

Silane coupling agents are included because they improve the bond between the resin and the substrate, providing better adhesion. Dimethacrylate resins are the primary structural components of many dental resins, forming the basis for their physical properties and cure. Polymerization inhibitors are also essential in resin formulations to control the setting time and prevent premature polymerization, ensuring that the material remains workable until it is needed.

Calcium hydroxide, while a material used in dentistry, particularly in pulp capping and various endodontic treatments, is not part of the formulation of resins. It serves different purposes, such as promoting the formation of reparative dentin and has different chemical properties compared to the aforementioned components, which are specifically designed to interact in resin mixtures. Thus, identifying calcium hydroxide as not typically included in resin compositions highlights its distinct role in dental materials compared to functional resin components.