Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: It works!

My teeth were definitely whiter after using this product. Although my gums hurt if the strips touched my gums. The directions say to use it 30 min in the morning and 30 min at night. Sometimes I just did them one after another, wearing the strips for one hour a day. I still got the results. Make sure you eat food and drink BEFORE using the strips. Only problem I had was that I would get hungry while wearing the strips and you can't eat while wearing the strips. I tried and the strips fall off and then your food tastes bad. Bottom line... product works.