I think you should buy the Pro crest. Mainly because the strengh of the bleaching agent is almost twice as strong as the regular crest. One you can buy at walmart and the other you can get at you dental office. The over the counter will bleach you teeth about 3-4 shades, but you will loose some of that the first time you drink coffee. I believe the cost is about the same. The only complaint I have heard is keeping the strip on the lower teeth.