just get them to blast you with injected anesthetic, then, when that takes effect, ask them to do it again...trust me
then take the nitrous and chill
after that the worst part is the noises and the waiting...and the shit they drill out of the inside of your tooth smells god awful and it shoots in your face...and your lips get real dry and cracked cause your mouth has to stay open for like an hour
they're not THAT bad though dude, i just cant imagine what they were like in the 1920's and shit...
get a good dentist though, i had to have one a couple years ago cause a filling fell out and got infected and the tooth died, but my dentist who did the canal left cotton and shit inside of it for some goddamn reason AND managed to miss a whole canal so it got super infected again and i had to have the whole thing redone. it was the dental equivalent of sewing a scalpel into a surgery patient. totally fucked.