This treatment has been described as effective by numerous people. The classic teeth whitening does not work on all teeth, especially if they are gray, as the effect is not visible, and it is only more effective when it comes to yellowish teeth.
This is one homemade recipe for teeth whitening. This method is really helpful. Note: The whitening does not act equally on every teeth. For example if you have grayish teeth the whitening can be invisible and in case of yellow teeth the whitening will.
DIY tooth whitening: Mix a tiny bit of toothpaste with 1 tsp baking soda & tsp water. Brush teeth for 2 minutes. Do this once a week until you reach desired results. From then on, use the treatment once every month or two.