Rank the following fluoride sources by their typical topical fluoride concentration from highest to lowest: toothpaste, mouthrinse, fluoridated water.

• A. Toothpaste > Mouthrinse > Fluoridated water
• B. Mouthrinse > Toothpaste > Fluoridated water
• C. Fluoridated water > Mouthrinse > Toothpaste
• D. Toothpaste > Fluoridated water > Mouthrinse

Answer: (A)

Topical fluoride concentration is about how much fluoride is available to contact the teeth during use, usually expressed in parts per million (ppm). Toothpaste contains a high fluoride level, typically around 1000–1500 ppm, because it’s applied directly to teeth during brushing. Mouthrinses usually have about 0.05% fluoride, which equals ~500 ppm—lower than toothpaste but higher than water. Fluoridated drinking water is commonly about 0.7–1.0 ppm, the smallest amount among these sources. So the typical order from highest to lowest topical fluoride concentration is toothpaste, then mouthrinse, then fluoridated water.