If somebody has a single dark tooth right in the front and it really shows that grey-ish color, we can bleach it, but that can only be done in the dental office. The reason being, we actually have to go inside the tooth to be able to bleach out. And why did this tooth get darker? Because bacteria has gotten inside of it. So usually if you had a fall, you had a root canal treatment in the front tooth - that's when we usually see that that can darken because bacteria has leaked inside the tooth. So we literally have to open it back up, put bleaching inside of it, clean it out, and then seal it back up.