Today's dentists have a lot of good ways to stop pain when performing their procedures. I, like you, had a lot of dental phobia and avoided the dentist for a long time. Finally my boss went ahead and forced me to see her dentist.
This guy was great and I became very relaxed with both him and the hygentist. He had to redo all my childhood dental work (my childhood dentist was so bad that he made me phobic) and I never felt one bit of pain.
He also made a nightguard for me since I had started to grind my teeth in my sleep which helped allieviate a lot of pain for me.
One thing that you might want to consider, is do some self systematic desentization, try imaging yourself in the dentist chair while placing yourself in a relaxed state, that should lower some of the anxiety.
Or do as Vonnegut suggested in Slaughter House Five, and just concentrate on happy thoughts while going through the procedure.
But, with the painkillers they got now, I don't think you will have any problems at all.