The occurrence of enamel fluorosis is reported to be most strongly associated with cumulative fluoride intake during enamel development, but the severity of the condition depends on the dose, duration, and timing of fluoride intake. The transition and early maturation stages of enamel development seem to be most susceptible to the effects of fluoride.

Concerns regarding the risk for enamel fluorosis are limited to children younger than 8 years; enamel is no longer susceptible once its pre-eruptive maturation is complete. (After age 6 years, only molars are still forming.)

It should be noted that fluorosis is purely a cosmetic condition. In fact, these teeth are actually less susceptible to dental caries!