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What is The primary mechanism of action of fluoride on topical application is - and explain in detail?
Ans. is 'a' i.e., Conversion of hydroxy-apatite to fluro-apatite by replacing the OH ions When hydroxyapetite is exposed to low fluoride concentrations (about 1 ppm) a layer offluorapetite forms on the hydroxyapetite crystals. The thin layer governs the rate of enamel dissolutin and reduces rate of caries progression. o During caries attack, the enamel is exposed to a pH of about 5.5 or lower, thereby leading to its dissolution. o The presence of fluoride reduces the solubility of enamel by promoting the precipitation of hydroxyapetite and phosphate mineral.