Thanks for the info Meg! i have Day White as well, but I think it's a lower percentage than yours.
mette-marit - I have listerine whitening wash, but I don't use it. There are a few types, but I have the one that you use after brushing your teeth (not the pre-wash one). The issues with it that i know of is:
a) You can't eat or drink 30mins after
b) You can develop the harmless but disgusting
black hairy tongue sounds rididculous, I know, but it's true, and reading a lot of listerine reviews, particulary pre-wash, some users have developed it. Apparently because the mouthwash is so strong, the good bacteria on the tongue gets killed as well. So do not use it as often as they suggest on the box. Defintely do not use it more than once a day.
c) skin peeling inside mouth
b) possible loss of taste
While it does apparently whiten, the side effects probably aren't worth it.
you can read reviews on Amazon about their pre-wash here (40 out of 70 people gave it 1 star)
http://www.amazon.com/Listerine-Whi...ageNumber=4&sortBy=bySubmissionDateDescending