On a weekly basis Smile Brilliant receives inquiries asking if the Invisalign can be used as a tooth bleaching/whitening tray. It's a good question considering they look like teeth whitening trays and form to your teeth with precision; however they are not ideal for teeth whitening.
The Invisalign is designed to merge/straighten your teeth which means it has a very snug fit. Granted teeth whitening trays fit your teeth precisely they still have a little "give" or space which allows the bleaching gel enough movement to prevent overflow in the mouth. When you apply teeth whitening gel to your Invisalign it will push most if not all of the gel out of the tray and into your mouth thus wasting the gel and causing irritation to the tissues in your mouth.
In conclusion we do NOT recommend using the Invisalign as a teeth bleaching tray.