First of all the chemistry behind crest white strips, do they actually work?
I have a package of Crest White Strips Premium plus my friend gave me from his work they have expired are they still effective after expiration date?
Borek
Jun16-08, 11:04 AM
Check what active ingredient is - that's answer to both your questions :wink:
Hydrogen peroxide is a strong oxidizer - so it may work. It is also unstable - so they can be not effective after expiration date, or at least less effective.
Hydrogen peroxide decomposes at a fast rate in water, I would still use the product since these strips have Hydrogen Peroxide imbedded in something other than water, however they may not be a great as one which has not exceeded the expiration date. Observe the package , if it seems inflated , than it's probably no good.