Hydroxyapatite Composition — NDEB AFK MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: C — Calcium phosphate in the form of hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂]
Hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] is the primary mineral component of all calcified dental and skeletal tissues. Enamel is approximately 96% hydroxyapatite by weight; dentin ~70%; cementum ~65%; bone ~65%. The crystalline structure of hydroxyapatite determines the physical properties of these tissues. Fluoride substitution for hydroxyl groups creates fluorapatite [Ca₁₀(PO₄)₆F₂], which is more resistant to acid dissolution — the basis of fluoride's caries-preventive mechanism.
Reference: Nanci – Ten Cate's Oral Histology, 9th ed., 2017