How do teeth whitening mouthwashes work?

Emma Wants White:

Hi! I love the site & am an avid reader! I am very interested in comparing ingredients between products nowadays thanks to your blog. My question is, is there a difference between using those whitening mouthwashes, and just swishing some hydrogen peroxide around your mouth? Since usually the first or second ingredient is peroxide that I can buy for less than $1.50 for a huge bottle, compared to the $6+ for these whitening mouthwashes, I was just curious.

The White Brain, uh, the Right Brain, Responds:

Smile Emma! We think the bigger question here is: do these mouthwashes really whiten your teeth? According to the ADA, professional toothwhitening is the way to go. Gee, what a surprise, the American Dental Association is firmly coming down on the side of paying dentists to do all your teeth whitening. But wait, perhaps we’re too cynical too soon. They also say that there are peroxide-based whitening products that you can buy over the counter and use at home!

Specifically, there are two ADA approved ways to whiten your teeth: you can bleach the stains (which is what whitening strips do) or you can physically abrade them (which is what toothpaste does). There’s no mention of whitening mouthwashes – why do you think that is?

Probably because mouthwashes can’t deliver a high enough concentration of the bleaching agent for a long enough period of time without damaging the tissue in the rest of your mouth. Remember, strips and toothpaste are applied directly to your teeth; mouthwash touches every where in your mouth.

There doesn’t seem to by anything wrong with using a “whitening” mouthwash, it just seems unlikely that it will be very effective – at least not as effective as the other methods. And the same goes for gargling with hydrogen peroxide.