miswak
A miswak is basically a stick from a specific tree and the stick is frayed at one end so it becomes brush-like. For all intents and purposes it is a toothbrush, but it is entirely natural and you don't need to put any toothpaste on it. The tree itself has proven beneficial for users throughout history, the miswak and its use as a toothbrush goes back to when the Qur'an itself was written. Matter of fact there are verses in the Qur'an that refer to using a Miswak to clean your teeth before prayers and meals.