Unlike whitening toothpastes,which only remove surface stains to reveal the underlying whiteness of teeth, bleaching agents actually make teeth whiter. The most common teeth bleaching agents are hydrogen peroxide and carbamide peroxide. The effectiveness of teeth bleaching depends on the color of your teeth. Bleaching works best for yellow stains,while gray teeth, which can result from certain antibiotics, are much harder to whiten.People who have stains from smoking,red wine or coffee can get very good results with teeth whitening. There are two different ways to get whiter teeth:dental (in-office) whitening, and using a home bleaching kit available through a dentist. A dentist applies a whitening gel,containing a high concentration of hydrogen peroxide, to your teeth, which is then activated by a special blue high intensity light or laser,causing the gel to release the oxygen molecules.The laser merely activates the bleaching gel,it doesn't actually penetrate the teeth. The results depend on the shade of your teeth before bleaching. While in-office teeth bleaching is the safest route to go, home teeth bleaching can be also be safe,and effective,if done properly and under the supervision of a dentist. Tray teeth whitening technique involves the use of a plastic tray that is filled with bleaching gel and then fitted over your teeth.By keeping the bleaching gel in contact with your teeth, for the prescribed period of time, your teeth will get whiter.Persons who are using the teeth bleaching products should always ask a dentist for advice. Increased tooth sensitivity and gum irritation and are the most common side effects of teeth bleaching.Some people even experience extreme pain.Your dentist will advise you on the appropriate steps to take if your teeth become sensitive during the bleaching process. Although the results of teeth whitening can vary from person to person, most people are very satisfied with their results.But if teeth bleaching isn't working for you or if have teeth that are shaped badly or crooked, veneers may be the option.