Hey well done you for coming off the Prozac! (I've been off antidepressants for a few months, after many years of taking them...feels very positive but a bit scary, and raw, like some 'armour' is missing, so I understand exactly what you mean about feeling 'unprotected') but it's bound to take you a while to settle down and get back to full mental strength. So the tooth business is just what you need right now, of course
But you'll handle it.
You could always tell the dentist if he's a sympathetic kind of person, that you're feeling a bit stressed and don't feel up to talking. I think dentists are used to nervousness in patients, it's a stress-inducing profession, maybe that's why they 'chat', to try and put people at their ease but I'm sure he'll understand if explain that you'd rather he just got on with it. If you can't tell him face-to-face, maybe you could drop him a note?
Your tooth pain might be causing, or a major factor in, the feeling of depression, so don't worry too much about it until your tooth is fixed...it might lift on its own once you feel physically better. Take it one day at a time, deep breaths, you can do this!
Good luck Claradoon!