Thin layer of enamel is removed; debris, tooth pellicle & chemically inert crystallites are removed. Which term describes this?

• A. Etched zone
• B. Dentin layer
• C. Pellicle layer
• D. Sealed zone

Answer: (A)

The key idea is that acid etching creates an etched zone on enamel. When enamel is prepared for bonding, a thin surface layer is dissolved by acid, removing debris, the acquired pellicle, and inert crystallites as the outer enamel is demineralized. This removes the smear and creates a rough, porous surface—the etched zone—that allows resin to penetrate and form micromechanical bonds. The other terms don’t describe this surface result: a dentin layer would refer to dentin tissue; the pellicle layer is the film that is removed, not the surface after etching; a sealed zone implies a surface that has been sealed, not the demineralized, porous layer created by etching.