you've never had fillings or anything?
every time I've had anything more than a cleaning done, they used nitrous oxide and a local anesthetic, which always really did the job for me
specifically what they did was use the gas, then rubbed some liquid on my gums (I'm not sure what. for some reason I remember it being pink, but I'm pretty sure that was just my little kid imagination) where they were going to inject the serious stuff, so that the shot didn't hurt so much
since you're older I'm not sure if they'd use the gum stuff, because it was just for the shot, and people who aren't kids can probably handle that on their own