APF solution concentration used for professional use is:

• A. 0.5%
• B. 1.23%
• C. 2.0%
• D. 5%

Answer: (B)

Acidulated phosphate fluoride is used in offices for topical fluoride therapy because its acidity helps fluoride penetrate enamel and promote remineralization. The concentration chosen for professional in-office use is 1.23% fluoride ion, which provides a potent, short-application dose (about 12,300 ppm) that enhances resistance to demineralization. The solution’s low pH around 3 makes it effective, but also means it can affect some restorative materials and soft tissues, so it must be applied under supervision with proper isolation. Other concentrations do not match this standard professional-strength APF formulation, which is why the 1.23% option is the correct choice.