Sorry but there is a lot of bizarre takes in this thread. I work in healthcare - the issue here is she LEFT you during a procedure to deal with another patient after comencing your procedure. What!? What other patient - she had already started a procedure on you and had anaethetised you and then left the room? And then by the time she came back and continued the procedure she got to the point where she couldn't provide any more anaesthetic?

The whole thing sounds like a mess. If for example she is running multiple rooms at the same time then that is frankly bad practice and greed.

Your friend's feedback that you "made the dentist feel threatened" is also bizarre. You're the one in the dentist chair, mouth open while someone is approaching your with drills and metal work. If she felt "threatened" then she should have abandoned the procedure completely - not leave and come back. Patients can be very anxious and tense - thats normal and either you know how to deal with it or you don't. As a health care professional on the occasions you can't deal with it, then you don't proceed - stop, make it safe and get someone else to do it. This was an elective procedure to fix a crown - why on earth would she then proceed with a procedure after having felt "threatened" - it doesn't make sense.

That dental practice sounds like a joke to be honest. Either your dentist is inappropriately treating multiple patients at the same time or she is indecisive - feeling threatened, walking off for safety but then coming back and completeing the procedure makes no sense and just made everything worse. You're hardly going to be less tense with this dentist after that experience.

Find another dentist.