Dentin Composition Percentages — NDEB AFK MCQ
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Correct answer: B — 70%
Dentin is approximately 70% inorganic (hydroxyapatite), 20% organic (primarily type I collagen), and 10% water by weight. Compare: enamel is approximately 96% inorganic, 1% organic, 3% water; cementum is approximately 65% inorganic, 23% organic, 12% water; and bone is approximately 65% inorganic, 25% organic, 10% water. The higher organic content of dentin compared to enamel makes it more resilient but also more susceptible to acid dissolution (critical pH ~6.2 vs ~5.5 for enamel).
Reference: Nanci – Ten Cate's Oral Histology, 9th ed., 2017