I used this system right before my wedding to whiten my teeth. I had previously whitened my teeth, so I only used it a few times to whiten up my smile which it did. However, my husband (then fiance) used the remainder of the kit and it did not work well on him. He has never whitened his teeth before but it was still disappointing because his teeth weren't bad to begin with. He doesn't smoke or drink coffee so his teeth were only slightly yellow. Very disappointing. I think for someone who has previously whitened it is an okay product.