Having similar experiences to yours in the past, I would suggest oh they know for sure what they do. All of it is a deliberate scam game.

I was lucky to find a decent dentist (and human being). And while I am not living in the country anymore, I still fly in for dental work.

Before you ask, I did try to find a replacement and it was just like you said - oh you have 25 cavities, 5 of them life threatening if we don't deal with it right now. Went back to my dentist and we laughed it out.

Its very unfortunate our healthcare is full of scam artists, with concentration of scammers likely comparable to scam call centers.