Anonymous wrote:dentists recommend waiting until children are at least 14 years old before considering teeth whitening for kids.
https://www.canyonridgepediatricdentistry.com

Simple Google search found this

This is one random dentist, so I wouldn't take it as the last word, although I don't really know whether whitening strips are a good idea or not.

Does she swim? Chlorine can cause intense yellowing, which can be addressed by more frequent dentist visits.

My DC complained about this also. Bought the strips, were used once, and then never mentioned again. If yours is similar, you might get lucky and she just wants to try them.