What is the concentration of fluoride in professionally applied gels used for high-dose topical therapy?

• A. 5,000 mg/L
• B. 12,300 mg/L
• C. 20,000 mg/L
• D. 1,000 mg/L

Answer: (B)

High-dose professional gels deliver a fluoride concentration that is much higher than what you find in home-use products. The typical in-office gel is about 12,300 mg of fluoride per liter, which is roughly 1.23% fluoride ion. This high concentration is designed to create a layer of calcium fluoride on the tooth surface during the short application time. Those reservoirs then release fluoride during subsequent acid challenges, helping to remineralize early lesions and inhibit further demineralization, which is especially beneficial for patients at high caries risk.

Other options represent lower-dose products or are not standard for high-dose in-office therapy. For example, a concentration around 5,000 mg/L or 1,000 mg/L would be considered too low for the intended topical, high-dose effect, while 20,000 mg/L would be unusually high and raise safety concerns for routine in-office use.