Prior to having the zoom 3 whitening procedure performed by my dentist, I did much research and read MANY reviews. All but a few described extreme pain. But, having coffee stained yellow teeth and only being 30 I went for it anyways. At the dentist the hygentist performed the entire procedure. She first discussed the procedure and the prep. She told my why they do the prep. She discussed all the side effects and (unlike many other people's dentist) she told me about the extreme pain ...in detail.... that I would feel after words. She herself had the procedure done on herself and experienced it first hand. Still I did it anyways. (I also had to sign a release form). She prepared me by drenching my face and my lips in sunscreen. I mean so thick that it looked like I was wearing a mask. She told me that it is to protect my face from the UV light. She used other stuff on my lips as well. She than piled on gauze around my tongue, and covered my lips. Next she used special pads and put them all over my lips. She may have used a tape like material to hold them on, but I am not sure. She said it was VERY important to protect all the lip including under the lip. She finished the "protection" on my lips and face and started to prep the gums. She used a selant type gel that hardens. She spent about 45 minutes making sure EVERY speck of gums were covered. She informed me that any part of the gums that are showing will severely burn if exposed to the light and or the bleach.She told me to immediatly report ANY sensation on my lips, gums, or face. After she prep'd my gums, she applied the two gels on my teeth. She placed the light on for 15 minutes. (Your dentist will either do 3 times at 20 mins each, or 4 times at 20 min each). After about 2 minutes she came back in and asked if I feel ANY sensation on my gums, lips, or face. I did. A small part of my front gums were burning a little. She immediatly took the lamp off and fixed the gum seal. I moved my mouth and broke the seal. Since the seal hardens, if you move it will crack. I made it through the first 15 minutes no problem. She took the gels off my teeth, reinspected the gum selants, replaced the gauze around my tongue and lips, reapplied the gels on the teeth and set the timer for another 15 minute round. AND THEN THERE WAS PAIN!!! About 10 minutes into the 2nd round of 15 minutes I felt those "zingers". Holy CRAP!!!!! THEY feel like someone is nailing your teeth nerves with a sledgehammer and tiny needles. OUCH. I have NEVER had pain like this. It was a pulsating type of pain. It lasted only a few seconds and passed. Then they happened again and again. Now, having passed a kidney stone, gone through 9 hours of "coupling" child birth labor pains, and having been stabbed in the leg I can honestly say that I would rather have all three of those happen to me at the same time than have this pain. Okay, so you say.... a painful zinger here and there... no biggy. It will eventually go away right? That is what I thought. I immediatly stopped the procedure, had everything taken out of my mouth and off my face, took the meds they gave me and left. The drive home the zingers were HORRIBLE. I went home and fell to the floor just rolling in pain. I called my regular dentist, and he had me come in right away. He is NOT a fan of the in office whitening procedures for this very reason. Anyways, he perscribed to me painkillers and a mouth wash that is basicaly Litacain (sp?). I picked up these items (in pain) and took them home. The zingers were not constant for me, and I only had about 10 every hour (although one in a lifetime is more than enough). So I didn't take the meds YET. I fell asleep. I woke up about 1 hour later and all he** broke loose in my mouth. Every one of my teeth were screaming with pain. Not quite the pain of the zingers, but none the less this was a constant pain. TERRIBLE pain. I didn't want to MOVE. I immediatly took the painkillers and used the mouthwash... and after an hour gave up hope that either of these would help. It was HORRIBLE PAIN. In the end, I had to stick it out. The pain lasted 17 hours total. The next day my teeth felt better, but were still sensitive (at a level that I could handle). Many people reading this my think I am weak, have a low pain threshold, etc, but if you do your research, you will find that I am NOT alone and MOST people who write the reviews will describe the same thing I am explaining now. Having said that this is the outcome. My teeth never whitened using the bleaching trays. That is why I wanted to try this procedure. I went in and my teeth were the yellowist color on the "teeth" scale before turning into the gray/yellow shades. Immediatly after the procedure my teeth were at the whitest on the scale (and remember I only went through 1 session at 15 min, and 1 session at 10 minutes). After a few days and after my teeth resealed themselves, my teeth were between the 3rd and 4th whitest on the white side of the teeth color scale (according to the many reviews I have read, this is common that they become less white after they reseal, unlike what the dentist tells you about your teeth will continue to whiten for 2-3 days... that is bull and I have yet to hear anyone confirm that they DO continue to whiten for the following 2-3 days). Anyways, I was sent home with more at home bleach to continue to use for the following 3 days ( after the pain I felt, I gave it more like 2 weeks). I never did use the 22percent strength formula they gave me to use. I just used a 15 percent peroxide tubes that I got from my original dentist. This took my teeth 1 shade white within a week. And I am happy with that. My conclusion is this. If you are willing to risk having to deal with the extreme extreme nerve pain in your teeth for about a day(50 x's worse than a root canal WITHOUT the numbing), possible 3rd degree burns on your gums, lip, tongue, etc,and you can afford to drop the money on this procedure than that is 100 percent your choice. I educated myself and new to make sure my gums, lips, face etc. were 100 percent protected. I went for it. Although the pain was extreme; and if you asked me on the day I had this pain, I would have told you that it is NOT worth it. For me, know that it seems to be overwith I would do it again. My teeth NOW respond using the bleaching trays at home as I was easily able to lighten them up a bite after my teeth darked a little. Fully educate yourself on what can go wrong with the procedure. My information on the severly burnt gums, etc are things I read about numerous time in other people's reviews of this procedure. But I used that information to be able to be better prepared to PREVENT things from going wrong. The meds don't help to take the pain away. My friend had the same procedure done, and was able to get a novacain (sp?) shot, and that didn't even phase the pain. Perhaps you will be lucky enough to NOT experience any pains or even just minor pains. There are those who report minor pain. I hope my experience will help you to make a good decision, better prepare yourself for the procedure, and make you more aware of some of the risks involved. Just a little FYI. One of my front teeth were damaged as a kid, and I have a veneer on it. On my picture, you may be able to see a difference in my front teeth. It is going to be replaced to match my other teeth, however, you should know that veneers, crowns, fillings etc. will NOT bleach. Mine did a little as the veneer itself was put on when I was 12 (before my coffee days) and the bleach was able to remove a good amount of surface stains, but it did NOT change the original color of the veneer.