Can anyone out there offer me some advice regarding the various teeth whitening products out there? There are three that stand out to me: the Crest Whitestrips, Rembrant's stuff (tray and gel), and another peroxide-based gel and tray). As far as I know, 16% carbamide peroxide is what is commonly used in the offices. I don't think these products contain specifically that. Are these OTC brands worth the cost? Can they damage the enamel? Any effect on gingiva? Thanks.