I had a load of dental work a couple of years ago because of clenching my teeth and wrecking them. I am not particularly scared of the dentist, but am really scared of injections, so I really sympathise. Things that helped me were:
Being totally honest about being nervous. My dentist is really lovely and gets the nurse to hold my hand during injections.
I had appointments at a time when I wouldn’t have to go back to work afterwards.
I brought lavender oil and put it round my nose just before going in.
I also brought something to fiddle with in my hands. It sounds silly but I took one of my cat’s beanbag toys (mainly because it was small, not because of the cat!) and squeezed it instead of clenching my fists or gripping the chair arms. Something like a Rubik’s cube woukd be good.
I had a “nice thing” planned for after every appointment. A bunch of flowers, an online order waiting at home, a lovely dinner. Just something I could look forward to.
When I went in, I would say to myself “by XY time I will be walking out of here, and this treatment will be over”. My dentist knew about this one, and she would say “we’re AB minutes in, CD minutes to go”. I had root canals which took AGES but I think an extraction will be quite fast!
Will be thinking of you tomorrow. I went to every appointment on my own, even though my DP offered to come to every single one. I didn’t want him to see me all upset and vulnerable, but I was really so grateful he was at home waiting for me afterwards. I generally felt quite triumphant after each appointment - hopefully you will too!