I’ve used Crest Whitestrips with fair-to-good results after 2 weeks to a month. They’re expensive, usually you find a coupon in the Sunday newspaper supplements for $5 off. The gummy little plastic strips are tedious to put on, and wear, for half an hour twice a day - though they may have invented a new improved kind by now. I would say, try the Whitestrips, make sure they adhere to every tooth (some of mine have shifted over the years, I used to smooth the strip against the out of line ones with a toothpick). I felt a mild tingling at times, if your teeth are real sensitive this may bother you, but I could put up with it…There’s a cheap system with a kind of mouthpiece you fill up with gel and clench in your teeth for a while, it didn’t do anything whatsoever as far as whitening, and it had good reviews! …ask any dentist and they will grudgingly admit Crest Whitestrips work a little bit, but for real white teeth, the only way to go is professional bleaching at the cost of hundreds of dollars! Imagine that!..OT but i’ve heard bleaching of teeth is addictive. I remember a bartender, a thin, skinny girl with nothing at all remarkable lookswise, but in the dim light of the bar her teeth were shining like the Cheshire Cat in Alice in Wonderland, with an eerie blue glow. Weird, and not so attractive as she would think.