Which teeth are most susceptible to fluorosis during the first three years of life?

• A. Permanent maxillary incisors
• B. Permanent mandibular incisors
• C. Primary maxillary incisors
• D. Primary molars

Answer: (A)

Fluorosis occurs when fluoride is ingested during the time enamel is forming, because fluoride alters the enamel mineralization process carried out by ameloblasts. In the first three years of life, the permanent maxillary incisors are actively forming and mineralizing, so they are exposed to fluoride during a key period of enamel development. This makes them the most susceptible to fluorosis compared with other teeth, whose enamel formation is completed earlier (as with primary teeth) or occurs in a different window. That’s why permanent maxillary incisors are the best answer.