The risk of enamel fluorosis in infants drinking reconstituted infant formula is positively associated with which factor?

• A. Fluoride concentration in the drinking water
• B. Number of meals per day
• C. Vitamin D status
• D. Water temperature

Answer: (A)

Enamel fluorosis risk hinges on fluoride exposure during tooth development. Infants reconstituting formula drink water with a certain fluoride level, so the fluoride concentration in the water directly determines how much fluoride the infant consumes from the formula. Higher fluoride in the water means higher total fluoride intake and a greater chance of fluorosis. The other factors—how often the infant eats, vitamin D status, and water temperature—don’t meaningfully alter fluoride exposure in this context. So, the fluoride concentration in drinking water is the factor most associated with enamel fluorosis risk.