Bests & Worsts Reviews from Amazon

I just offer this as a warning. I ordered this product through Groupon but I can no longer find a place on their website to rate it, or on the Smile Bright website. The documentation that comes with the product says that on the first use, to do two 20-minute applications, back-to-back. I used it for one 20-minute application and barely made it through. The paste burned my gums so badly that the next day, a layer of skin sloughed off. Obviously, I did not use it again but after three days, my gums are still so tender that it's difficult to brush my teeth. I did notice some whitening effect after the first use but obviously, I'll not use it again. I was not aware that my gums were any more sensitive than any other person's so it did not occur to me that this might happen. Just be aware of the possibility and when using the gel, if it hurts, spit it out.