What can I buy to safely whiten teeth?

Dentist supervised. For the best results, consult a dentist for a take home tray system that is custom made to your teeth and you apply the gel every night to lighten your teeth.
Professional. Need a dentist. Best to have your teeth thoroughly and professionally cleaned prior to having your teeth whitened. Same goes for fillings, crowns, etc. Treatment should be done first.
Depends. How dark are the teeth? For mild discoloration, or for someone who wants minor color change, try crest whitestrips or cao sheerwhite!. But if you want a moderate or major color change, see your dentist. I have had great success with 1 or 2 in- office zoom! led treatment and dispense custom fit home trays with either 10%, 16% or 22% nitewhite or 14% daywhite. Or kor whitening system.
Plenty. There are many teeth gadgets available to whiten teeth but the fast way to whiten it is to gargle with a capful of hydrogen peroxide for at least 1o mins.
Safe vs wise choice? There are several issues here to consider. While there are many safe tooth whiteners on the market, both otc and dentist supplied, first you need to be sure that you have healthily teeth and gums. Whiteners do not whiten fillings and crowns. See a dentist for a consult and then you will be informed what is best for you.