What to do if i have really yellow teeth. i brush once a day with crest. but i need help how to whiten them?

Need help: See dentist for professional cleaning. Learn how to properly clean your teeth (if you're only brushing 1x/day for less than 2 minutes each time, you're failing). Your dentist can then recommend the best whitening system for you.

Teeth Whitening: Fortunately, professional teeth whitening/bleaching is an incredibly effective and fast way to lighten or altogether eliminate stains and achieve a naturally white smile.