I had to have a tooth removed and was reffered by my normal dentist to another clinic. When I got there they asked if it was ok to be done by a student dentist as they were a training practice, but they'd be supervised by a fully qualified. An hour in and she couldn't get it all out, the tooth had fragmented and the last but wouldn't budge, despite what felt like cartoon like yanking and pulling. The qualified dentist had to take over and got it out in 5 minutes.
All I learned from it was to go in clean shaven, all the yanking from different angles kept trapping my beard and it was more pain on my face as they kept trapping hair, than I felt in my mouth.