Question

What is the benefit of Fluoride content in toothpaste?

Answer 1

pH of mouth and tooth decay.

• In our mouths after eating sweet-tasting food, carbohydrates and other food particles like chocolates undergo bacterial decomposition to form different acids such as Lactic acid, Ethanoic acid, Butanoic acid, etc.
• As a result, the pH of our mouth comes down to 5.5, then the tooth decay starts.
• Tooth enamel which contains Calcium phosphate(${\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2$) reacts with these acids to form soluble Calcium salts and in long run, we get cavities in our teeth.

Benefits of fluoride:

• To prevent this decay cleaning of the mouth is required, at least two times a day using fluoride toothpaste.
• In Fluoride toothpaste, Sodium fluoride is added which reacts with Calcium phosphate present in our teeth to form insoluble Calcium fluoride and as a result acids cannot attack further.

$\underset{(\mathrm{Calcium}\mathrm{phosphate})}{{\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2\left(\mathrm{s}\right)}+\underset{(\mathrm{Sodium}\mathrm{fluoride})}{6\mathrm{NaF}\left(\mathrm{s}\right)}\to \underset{(\mathrm{Calcium}\mathrm{fluoride})}{3{\mathrm{CaF}}_2\left(\mathrm{s}\right)}+\underset{(\mathrm{Sodium}\mathrm{phosphate})}{2{\mathrm{Na}}_3{\mathrm{PO}}_4\left(\mathrm{s}\right)}$