Acid etch is used to prepare which surfaces for bonding?

• A. Enamel
• B. Dentin
• C. Both enamel and dentin
• D. Cementum

Answer: (C)

Acid etching works by creating a rough, porous surface that allows resin to penetrate and lock in for a durable bond. On enamel, phosphoric acid removes the smear layer and forms micro-porosities, so resin tags can interlock with the enamel prisms for strong micromechanical bonding. On dentin, the acid demineralizes the surface enough to expose a collagen network; adhesive monomers infiltrate this area to form a stable hybrid layer that bonds resin to dentin. Cementum isn’t the typical target for routine bonding, so enamel and dentin are the surfaces prepared by acid etching.