Before toothpaste was invented, there were a few ways people cleaned their teeth. One way people cleaned teeth before minty fresh toothpaste was ashes from a fire! You'd think ashes would make teeth look filthy. It was the crystals in the soot that was thought to whiten teeth!
Some people say lemon juice is an effective way to clean teeth. The reason lemon juice works to whiten teeth is because it causes your teeth to lose calcium, which is a huge part of healthy teeth. Also, lemon juice is an acid, and prolonged exposure on the teeth can cause tooth decay. Once calcium is lost, your teeth become quite vulnerable to tooth decay.
Some say mixing baking soda with your tooth paste works to whiten teeth. Toothpastes even now have baking soda in them, but baking soda is an abrasive and can sand the enamel right off your teeth! Always check with your dentist before you try any at home remedy-and always brush with a fluoride toothpaste!