From what I know, there will be no problem with continuing to fast while you go to the dentist. If your dentist is removing the Amalgams properly, which you indicated will be the case in your previous post, I really don't think there is a reason to worry. The only thing is, when I fasted I was already feeling weak around day 13 and I was a little wonky so I'm thinking you may want to have a friend drive you or get a cab or something, just to stay on the safe side. You will be fine :)