Restorative & Materials · single question
How does saliva contribute to the remineralization of enamel?
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Correct answer: C. Saliva contains calcium and phosphate ions which help remineralize enamel
Saliva is supersaturated with calcium and phosphate ions (Ca²⁺ and HPO₄²⁻), especially near neutral pH. When acids from bacterial metabolism lower the pH, minerals dissolve from enamel (demineralization). When pH rises (buffered by saliva's bicarbonate), calcium and phosphate ions re-deposit into the enamel hydroxyapatite crystal lattice (remineralization). Fluoride, when present, also incorporates as fluorapatite, which is more acid-resistant.
- A. CORRECT. Saliva is supersaturated with calcium and phosphate, providing the ions necessary to reprecipitate hydroxyapatite into enamel during remineralization.
- B. Incorrect. While saliva does contain antibacterial components (lysozyme, lactoferrin, sIgA), it is not primarily 'bactericidal' against S. mutans. Its remineralization role is ionic, not antimicrobial.
- C. Incorrect. Mechanical cleansing occurs but is not the primary mechanism of remineralization. Remineralization is a chemical process dependent on ionic content.
- D. Incorrect. Lowering pH would PROMOTE demineralization, not remineralization. Saliva actually raises pH (buffers acids) to allow remineralization to occur.
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