Fluoride protects teeth against caries primarily by which biochemical mechanism?

• A Stimulation of odontoblast proliferation and secondary dentine deposition
• B Conversion of hydroxyapatite to fluoroapatite, which is more resistant to acid dissolution ✓
• C Direct bactericidal action against Streptococcus mutans
• D Increasing salivary calcium and phosphate supersaturation

Explanation

Fluoride ions replace hydroxyl groups in hydroxyapatite crystal lattice to form fluoroapatite, which has a lower solubility product and resists acid attack from bacterial glycolysis. Fluoride also inhibits bacterial enolase at high concentration, but the principal protective mechanism is structural modification of enamel mineral. It does not kill organisms outright nor act mainly through salivary composition changes.

Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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