Oh I hear ya.
I skipped the dentist for... hmmm... 41 years. No kidding. I had ONE root canal during that time, otherwise... never.
Until I started suspecting I was going to transition, and realized I had to do something about my teeth.
So in spite of the fear, over about six months, I had two growths sliced out of my cheeks (I tend to chew my cheeks when nervous), 15 fillings, and... the most fun part of all... two porcelin veneers placed on my front teeth.
Ironically, the veneers were far, FAAAAAR worse than ANYthing else I've done by a factor of 100x. Fillings... piece of cake in comparison. Just go to your Happy Place, and don't overthink too much. Focus on the goal, the end results - know you're going to walk out better than when you walked in

A year ago, the thoughts of the dentist terrified me. Now... it's just, "Hi doc. Fix me." No biggie. Really, you get used to it, once you go through it a couple... err... dozen times

Kate