Root canals. The procedure has come a long way since the 90s and is relatively smooth and painless now. Obviously having a good and skillful edodontist also helps, but it’s no longer excruciating like decades ago.
Can confirm. The pain kept me awake the night before my appointment, so I was quite tired while having my canals filled. As soon as the dentist had given me a couple of anesthetic shots, I had to struggle to stay awake. I felt nothing during the procedure, and the only pain after was in my wallet.