Charcoal: Once upon a time, these toothpastes and tooth powders did not exist. But the teeth of our ancestors were sparkling white. Even in this age, our grandparents, especially those in villages, do not use toothpaste at all. But their teeth are white. The secret is charcoal. Yes, charcoal whitens teeth. They are also strong. So if you want to whiten yellow teeth, use charcoal. It has no side effects.