In my limited (to me) experience, every dentist I've ever had would give me the numbing shot, wait 10-15 minutes, and run a pick over the tongue in that quadrant of my mouth and ask if I felt it. Which I invariably DID. What they used to use (may still do, but I don't get it anymore!) was lidocaine. At dental strength, whatever that may be, lidocaine does not handle my pain. Enough of it will make me appear to be a stroke victim, with extensive facial sagging, but the pain receptors work JUST FINE. Sometime in my mid-20's, I asked a new dentist to find something else to try on me, as I was truly sick and tired of pain every time I got more than a cleaning - and I have horrible teeth, nearly every visit was more than a cleaning. He used a new-to-me drug and, wonder of wonders, it worked. It metabolizes out faster than lidocaine, but it works on MY pain... Before that happened, I got my wisdom teeth pulled at a dental school in Los Angeles. 4 shots of lidocaine later, I looked awful! Even with an IV of valium and demerol, I still felt the pain, and because I was so drugged up, I cried throughout the procedure. Talk about a miserable day. I still cringe and tense up as soon as I hear the drill, even though I no longer feel the pain.