Is there any way I could whiten my teeth without buying anything?

I heard about the peroxide and baking soda. How does that work? What are you supposed to do?
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Baking soda is an option. In making a decision you should consider the level of discoloration of your teeth. Care must be exercised to prevent damage to the teeth enamel. You can compare effectiveness and cost of at-home methods here: http://the-dental-makeover.com/whiten-te…
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