We haven't tried this ourselves, but it sounds like an amazing way to stay natural and keep your teeth white. This is recommended no more than once per week as it produces a strong acid whicih can damage your tooth enamel if used excessively. Let us know if you've tried this and how it's worked.
1 very ripe strawberry
1/2 teaspoon baking soda (Arm & Hammer, etc.)
Instructions: Crush the strawberry down to a pulp, and then mix with the baking powder until well blended. Use your soft toothbrush to spread the mixture onto your front teeth. Leave it on for 5 minutes, and then brush thoroughly with toothpaste to remove the berry–baking soda mix. Rinse. (Some dental floss will help get rid of any strawberry seeds.) You can apply up to once a week.