I used it for the first time tonight and it definitely started to make my teeth look whiter, but it basically pulled out all of the flaws in my teeth and exposed them! I will keep you posted once I have done this a few more times to see if this product actually works or is just a pain. I have professionally fitted trays from my dentist, so I didn't use the ones given in the kit here, but they seem like the standard ones.Definitely made my mouth sore. Luckily I had purchased the remineralizing gel separately, which helped immensely. That stuff has a faint mint taste to it and is definitely worth buying! Totally takes away the soreness after using the whitening gel. So far, looks like a good buy...