I too would not recommend having the Zoom! whitening done. I had a severe reaction to it about midway through the whitening process. I began having an adverse reaction the the product once the light was applied. Terrible shooting nerve pains that shot from my teeth all the way into head. The whole process was supervised by my dentist whom I trust very much, and he said although rare, serious adverse reactions do occur. I paid a lot to have it done and by the time all was said and done, my teeth were 6 shades lighter and I had a headache, mouth pain and tooth sensitivity that lasted for about 3 weeks. Definitely NOT worth it to me!