After cavity preparation, the openings of tubules are opened by which process to enable resin infiltration?

• A. Air drying
• B. Light curing
• C. Acid etching
• D. Polishing

Answer: (C)

Opening the dentin tubule openings by removing the smear layer and demineralizing the surface with acid etching is what allows resin monomers to infiltrate the dentin, forming a strong bond. The smear layer covers tubule entrances after preparation, blocking resin penetration. Phosphoric acid etching dissolves that layer and partially demineralizes the surface, exposing the collagen network and creating microscopic porosities. This enables resin to infiltrate the surface and, upon curing, form a durable hybrid layer that provides micromechanical bonding between dentin and adhesive/composite. Other options don’t create these pathways: air drying simply removes moisture, light curing hardens the resin, and polishing is a finishing step that doesn’t open tubules for infiltration.