One of my DDS friends hooked me up awhile back with a dental whitening kit (16% solution - There are different % solutions depending on individual sensitivity) and custom molds. Carbamide Peroxide equivalent, peppermint cream flavor and works really well for whitening. Never ued OTC stuff.
i asked my gf who is a dental assistant about them. she said dont waste my money.... she said they dont work well and arent good for your teeth or something along those lines...
Well I bought those strips and started to use them. They were working great except my teeth got a lil sensitive. After discussing it with one of my Dental friends, he told me i should've gone to him first. He gave me a free kit (usually charges almost 600 bucks). Teeth are bright white now. :-D
He gave me a kit, Discus Dental Whitening. check out their site www.discusdental.com