I am a dental hygienist and I tried this product after talking with a sales rep. I used the 32 percent LumiSmile formula and it was very painful. I had to remove it after only 2 minutes. I used this with custom trays that were filled according to the product's instructions, so I don't feel that I did anything wrong with applying it.
Sorry to write a negative review, but after my experience I would never recommend this to anyone.