She's already in trouble with the law for what she did and I would be willing to say that she'll never work as a dentist again - so she's already lost her livelihood.
Besides, I did say that it was wrong - meaning it was wrong of her to do what she did. However, I can say this - if you have ever been cheated on, think back to those feelings you had right after it happened and tell me that you weren't pissed off. According to this article, the dipshit went into his ex's dental office two days after he told her he was dumping her for another woman and expected her to work on a tooth that was hurting him.
Neither of them are too bright - him for thinking he could have her fix a problem for him after he dumped her for another woman and her for doing what she did. I can at least understand the emotions behind what she did.
I want to say something sarcastic like "God forbid a professional actually do what you're paying them for without doing harm" but its not going to come off all that well.
Generally when you go to a professional to have some work done, regardless if its a dentist, optomitrist, doctor, whatever you're trying to trust that person to do what you're paying them to do. Its possible that he didnt know she, specifically, would be doing it and at that point youre kind of backed against the wall. Deal with more pain till a new dentist is available or trust her to do the right thing
Lets give him credit where credit is due, at least he broke it off. Instead of moving on and acting like an adult she went over the line both personally and professionally