What term describes the bonding layer applied to enamel and dentin before placing composite?

• A. Bonding Agent
• B. Etchant
• C. Varnish
• D. Sealant

Answer: (A)

The bonding agent is the layer that creates adhesion between the tooth and the composite. After preparing the enamel and dentin surface (often with a conditioner or etchant to roughen it), the bonding agent infiltrates the micro-porosities and forms a hybrid layer with dentin and resin tags with enamel. When cured, this adhesive matrix locks the composite to the tooth, reducing microleakage and improving retention.

Etchant describes the acid conditioner used to prepare the surface before bonding, not the adhesive itself. Varnish is a protective coating used in different contexts and not the bonding layer for composites. Sealant refers to a resin placed in pits and fissures to prevent decay, not the bonding layer between tooth structure and restorative resin.