The recommended concentration of acidulated phosphate (APF) fluoride gel is:

 # The recommended concentration of acidulated phosphate (APF) fluoride gel is:

 A. 2%

B. 8%

C. 1.23%

D. 10%

The correct answer is C. 1.23%.

Brudevold's solution or APF solution is prepared by dissolving 20 gms of NaF in 1 Litre (2% NaF) of 0.1M phosphoric acid and to this 50% hydro fluoric acid is added to adjust the pH at 3.0 and fluoride ion concentration at 1.23% APF gel is prepared by adding gelling agents like methylcellulose and hydroxyl ethyl cellulose and the pH is adjusted between 4-5.