i take about two and half times the normal injection of local anesthetic, and it generally wears off in about the time it take to kick in for normal people.
Well my old dentist screwed up one of my teeth and when i came back the pain was so bad that 2.5 doses had no effect on me not even a numbness of the face. After that i changed dentists and when the second one pulled one of my teeth he gave me 1 dose i dint feal my whole face for 2 hrs and for half an hr i felt like i was drunk. My best guesses are that my first dentist was somehow watering down the drug or something or that my second one had a different and better one.