Alex and the dentist are usually open enemies (at least on Alex's side). He may tolerate it for the sake of the elevator but he'll resist as much as he thinks he can get away with. Initially, we had to put him under general anesthesia for his cleanings and then we moved up to a full body restraint board.
Yesterday, we strapped him into the restraints and he was actually cooperative. He didn't fight to wriggle out of the restraints. He opened his mouth for ten seconds at a time (a personal best). He asked politely to get down rather than trying to throw himself off the exam chair. (I had to tell him no but told him I was proud he asked.)
I don't think it's a coincidence that he's doing better and we've been doing the behavioural programming. Hopefully we can keep it up.