Tooth Whitening (Bleaching): Bleaching teeth is one of the fastest and most popular ways to brighten a smile. The procedure, which can be completed in the office or at home, can bring up the color of your teeth from 5 to 8 shades (somewhat less if teeth are gray or brown due to tetracycline staining) and will last for months or years depending on how well you take care of your teeth and if you avoid coffee and other staining agents.