Can bleaching kits make teeth white?

For around $20, you can find teeth whitening kits in drug stores. These kits claim to make teeth white with the application of some bleaching gel. Generally, you have to wear a mouth tray consisting of bleaching agent on your teeth for a few hours a day. These kits are effective when you use them continuously for a few days. However, ADA has not approved these kits, as the bleaching gel is acidic in nature. If you use very strong kits, your teeth enamel may be affected. Normally, when you use such kits to make teeth white, your teeth will become sensitive for a few days.