For composite restorations with at least 0.5 mm remaining dentin thickness, which material is used to promote adhesion?

• A. Bonding agent
• B. Liner
• C. Sealer
• D. Base

Answer: (A)

Adhesion in composite restorations to dentin relies on an adhesive system that creates a resin-dentin interface. After preparing the cavity and etching, the dentin is primed and bonded with a bonding agent. The resin monomers infiltrate the demineralized dentin, forming a hybrid layer that micromechanically locks the resin to the tooth structure. This bonding step is what provides the durable adhesion needed for the composite to stay in place.

Having at least 0.5 mm of remaining dentin thickness means you can apply the bonding agent directly to dentin without needing a liner to protect the pulp for adhesion purposes. A liner is used when the dentin is thin to protect the pulp and encourage dentin formation, not to promote adhesion. A sealer serves a root canal sealing function, and a base is used for bulk or thermal insulation under restorations, not to enhance bonding. Therefore, the material that promotes adhesion in this scenario is the bonding agent.