Don't throw away your banana peels. Use the fleshy part on the inside of the peel to gently rub away dinginess on your teeth. Do this daily for about five minutes, rubbing only on your teeth, not your lips or gums. Brush your teeth with toothpaste and water afterwards, using a gentle circular motion. Rinse well. The potassium, magnesium, and natural acid help break down stains on teeth. The grittiness of its fiber also helps polish your enamel.