Question

The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ions are required to make teeth enamel harder by converting $\left[3C{a}_3\right(P{O}_4{)}_2.Ca\left(OH{)}_2\right]$ to

• A. $[3Ca(OH{)}_2.Ca{F}_2]$
• B. $Ca{F}_2$
• C. $\left[3\right(Ca{F}_2).Ca(OH{)}_2]$
• D. $[3C{a}_3(P{O}_4{)}_2.Ca{F}_2]$

Answer 1

The correct option is D $[3C{a}_3(P{O}_4{)}_2.Ca{F}_2]$

Tooth enamel is chemically calcium phosphate hydroxyapatite.

In the process of demineralization of teeth, flourine converts calcium phosphate hydroxyapatite to calcium phosphate fluorapatite.

$3C{a}_3(P{O}_4{)}_2.Ca(OH{)}_2+2F^{-}\to 3\left[C{a}_3\right(P{O}_4{)}_2.Ca{F}_2+2O{H}^{-}$