Safely whitening Teeth? :S?

I am a Teenager and I recently stopped brushing my teeth for days at a time. Now I think of it I regret it a lot :S But now I Have started to Brush my teeth 2 times a day. The problem is that they are slightly yellow.... Is there any brand or product I can use which will whiten my teeth without any abrasives or ingredients which can damage my teeth or gums? and also if so, how long roughly would it take? And one last thing, I read About Orbit White Chewing Gum. Apparently it whitens teeth? could i have some information please :P help with any of this would be appreciated. Thank you! :D
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A lot of products will make your teeth sensitive but I use plus white speed whitening gel. I have really sensitive teeth and that hasn't been bad on them at all, it's cheap, and it seems to be working! You're not supposed to get it on your gums but then again you aren't supposed to get any whitening stuff on your gums really. Also, Orbit white may help but it won't give you dramatically whiter teeth. :)
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