Which material is NOT ideal for placement under a composite restoration?

The material that is not ideal for placement under a composite restoration is Zinc Oxide Eugenol. While Zinc Oxide Eugenol (ZOE) has properties that can be beneficial, including its sedative effect on the pulp and its ability to provide thermal insulation, it can interfere with the bonding properties of composite materials. The presence of eugenol can inhibit the polymerization of composite resins, leading to inadequate bonding and reduced longevity of the restoration.

In contrast, Calcium Hydroxide is used under composites for its pulp-capping benefits, as it stimulates the formation of reparative dentin. Zinc Phosphate offers good mechanical properties and some thermal insulation, making it a reliable choice in certain cases. Glass Ionomer cement is often favored as it bonds chemically to tooth structure and releases fluoride, contributing to both adhesion and caries prevention. These materials enhance the effectiveness and longevity of composite restorations, making them suitable for this purpose.