Yeah, the teeth... But with black tea it's even worse, imho.
I recently stumbled over a YT video which basically advised to mouthwash 1-2 minutes/2 times a day using olive oil to get rid of the coloring.
I had one try so far, but as my sinuses are still clogged, i couldn't really breathe and it was quite a pain to get to the full 2 minutes.
Maybe you want to try, but afaik myself, i will hang on trying this out and report my personal experiences here.

Respect for self-roasting. It tickles me hard to look into this as well, and then usually things get out of control very quickly 
Especially since i already got some roasting experience regarding Cocoa.