You will NOT see good results when using invisalign trays to whiten your teeth. Our custom-fitted teeth whitening trays are very different from Invisalign retainers. Invisalign is designed to help shift your teeth during orthodontic procedures. They are made from rigid material and have an incredibly snug fit. Using invisalign trays to whiten will result in all the whitening gel oozing out. This will waste the gel and cause irritation to the tissues in your mouth. Our custom-fitted teeth whitening trays are made with thin and flexible. They are also designed with a reservoir so gel can stay in constant contact with the teeth (instead of oozing out).