6. Activated charcoal
Ever used black toothpaste? The working ingredient in this teeth whitening solution is activated charcoal. This substance clings onto the teeth-staining tannins that are found in almost every food and drink. With continues use, it will whiten your teeth. You can make your own powerful teeth whitening substance at home, by mixing a small capsule of activated charcoal with a tiny amount of water. Apply to your teeth, let it sit for several minutes, then rinse!