At what age is a child most at risk for dental fluorosis affecting permanent teeth?

A child is most at risk for dental fluorosis affecting permanent teeth between the ages of 15-30 months. This is a critical period when the permanent incisors and first molars are developing, making them particularly susceptible to excess fluoride exposure.

Dental fluorosis occurs when children ingest an excessive amount of fluoride during the years when their teeth are forming. During 15-30 months, children are often transitioning from a diet primarily consisting of breast milk or formula to solid foods and may begin using fluoride toothpaste, increasing the risk of unintentional consumption.

In contrast, both the 1-6 months and 6-12 months age ranges are earlier developmental stages when the exposure to fluoride is typically less of a concern. By the age of 3-5 years, while permanent teeth are still developing, the most critical period for risk of fluorosis has already passed, and permanent teeth have begun to calcify, lowering the risk compared to the earlier ages.

Therefore, the peak risk for dental fluorosis directly corresponds to the critical developmental window of the child's teeth, confirming why the age range of 15-30 months is the most relevant in this context.