Cleaning teeth with charcoal

I was looking at the 1842 bound edition of Information for the People, and I came across an issue on personal hygiene, p. 656. For cleaning teeth the method suggested state:

"...we know of none better than finely-powdered charcoal... by putting a little of this on the wet brush, and rubbing the teeth with it, impurities and discolourations will be removed without injuring the enamel. Rinse well afterwards with water."

That sounded very strange to me but I looked it up and found you can buy Activated charcoal to clean teeth these days as well as a Youtube video of a woman using charcoal to clean her teeth. It seems to work. https://www.youtube.com/watch?v=xETW8UrBuzU

So, it looks like some 19th century knowledge and practices are still circulating in the world.