Hydrofluoric Acid Ceramic Etching — NDEB AFK MCQ
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Correct answer: A — 5-10% hydrofluoric acid
Hydrofluoric acid (HF, 5-10%) is used to etch the intaglio surface of glass-ceramic restorations (feldspathic, leucite-reinforced, lithium disilicate) to create microretentive porosities for adhesive bonding. HF selectively dissolves the glass phase, creating a roughened surface. Etching times vary: feldspathic (60-120 seconds), leucite-reinforced (60 seconds), lithium disilicate (20 seconds). HF is TOXIC and must be handled carefully — it should never be used intraorally (only on extracted teeth or on the restoration extraorally). Phosphoric acid is used on tooth enamel but is ineffective on ceramics.
Reference: Anusavice – Phillips' Science of Dental Materials, 13th ed., 2022