You can whiten your teeth naturally with some household items.
1) Brush with baking soda: baking soda is known to have withening properties, it helps get rid of surface stains on the teeth. It also create an alkaline environment in the mouth making it difficult for bacteria to survive.
2) Rinse your mouth with hydrogen peroxide: hydrogen peroxide is a bleaching agent, it helps take of stains and kill bacteria present in the mouth. Most toothpaste now contain little amount of baking soda and hydrogen peroxide.
3) use activated charcoal: brushing with activated charcoal takes of stain from the teeth.
4) Use strawberries: it is believed that malic acid in strawberries help in teeth whitening. Many use the mixture of strawberries and baking soda.
Fruit peels are also known to be effective. Brushing and flossing daily and regular visit to the dentist is the best way to prevent building up of plaque on the teeth.