Since kids have very soft enamel is is incredibly prone to acid erosion and decay. Acid erosion is very common since most children have very acidic diets (fruit, fruit juices, apple sauce, lemonade).

The tricky thing about acid erosion is that you can not always see is visually... but check with your dentist the next visit.

I actually work with Sensodyne who just came out with a great new ProNamel for Children that was designed with dentists to help prevent acid erosion, cavities and re-harden their enamel.

I would be more than happy to share any other information. Just ask :)

Pronamel is a good product but it contains stannous flouride. It will be improved as they continue to work with masking the taste of the rather bitter ingredients. As the previous comment suggests it does help in the healing of erosion if it hasn't progressed too far.