Etchant
Pronunciation: EE-chant
An acidic agent—most commonly 30–40% phosphoric acid gel—applied to enamel or dentine to remove the smear layer and create microporosity for resin bonding.
Full Definition
In adhesive dentistry, etchants demineralise enamel and dentine surfaces to expose collagen fibrils and create resin-receptive microporosities that allow monomer infiltration and micromechanical bonding. Phosphoric acid (H₃PO₄) at 30–40% concentration is the standard etchant for total-etch adhesive protocols, applied for 15–30 seconds on enamel and 15 seconds on dentine. Selective enamel etching applies phosphoric acid only to enamel in combination with self-etch adhesives. Editors should not confuse 'etchant' with 'primer' (the subsequent adhesive component) or with HF acid (used for ceramics, not tooth surfaces).
Usage
Usage note: Distinguish 'etchant' from 'primer'; they are separate components in multi-step adhesive systems. Specify the concentration and type when editing methods sections.
In Context
- "A 37% phosphoric acid etchant was applied to the enamel margins for 30 seconds before primer application." — Restorative dentistry methods section
- "Selective enamel etching with a conventional etchant was combined with a two-step self-etch adhesive to optimise marginal integrity." — Clinical protocol paper