OP, i was in the exact same position as you are now.
I've been terrified of the dentist for years, since bad treatment by a sub-standard bastard dentist many years ago (he was struck off the register for it).
I posted at Christmas on AIBU asking for help with dreadful toothache, which no painkillers would touch.
I'd delayed going back for the initial treatment so long since 2014 due to fear of the dentist, and was climbing the walls in agony, and no painkillers worked.
My dentist said, patients with fear are in a catch 22. They delay seeing him for as long as possible because they are scared, and then only attend because it's absolutely unavoidable, by which time the damage can go further than it would have been originally , so treatment can take longer- which in turn makes them even more nervous for future visits!
But from this recent visit, a double extraction (2 weeks ago so fresh in my mind), i can say it was not painful. It didn't hurt, and the dental nurse was brilliant in relaxing me. There was pressure, and noise, but at no point was I in pain.
When he said, "That's it, you're done" the relief was so intense I burst into happy tears and told him he's the best dentist in the world
I'm sorry this is quite long, I just wanted to share with you OP as I've been terrified for years, but seeing such an understanding dentist, who helped me relax and trust he knew exactly what he was doing, made the treatment as comfortable and quick as possible. I believe this good experience has cancelled out the previous bad one, and re-set my fear.
If I have any future problems, I'll be there straightaway. I'd never have said that a month ago!
Good Luck OP