How old should you be to use crest white strips?

Answer 1

The way they work ...

Stains get caught in small holes in your teeth. Any whitening agents will 'bleach' out these stains. However it also opens the holes, so it's important to follow up with additional flouride such as Act original. If you use a lot of flouride on already stained teeth, it will be that much harder to whiten. Speak with your dentist.