Why wouldn't dental anesthesia not work during a root canal i was having a pulpectomy on a hot tooth and none of the shots worked. i felt everything! even after i left none of my mouth was numb. now i am afraid to have any more dental work. even though i

Hello, Good : Hello, good question! local anesthesia works by blocking chemicals that move into and out of nerves in the in contact with the local anesthetic. This means that in order for it to be effective and last long enough for the procedure in question it the anesthetic must be the right drug, location and conditions for them to work. Now, assuming your dentist injected the right drug in the right location, the only thing remaining is the conditions present in the area. For reasons outside the scope of your question, the environment around an infected area is difficult to anesthetize. In general it is an acidic environment. Local anesthetics work poorly or not at all in acidic tissues. So, this is why you felt what you felt. One last thing, local anesthetics are not good at blocking pressure. So even during a perfect block, you may feel something. Just not pain. Hope that helps. Thanks for the question.

To : To add on to the prior excellent response, it's possible that the infection was in your gums as well as your tooth. Local anesthetics, like what you had, don't work in regions with infection present because the acid/base status of the surrounding tissue doesn't allow the medication to work.

Dental nerves: Nerves inside of a tooth come from many different locations. Dental infections sometimes make Lidocaine less effective due to the acidic environment. To make you more comfortable a dentist needs to give Lidocaine or Carbocaine (sometimes works better in an acidic environment). Also the location of the anesthetic may need to be adjusted due to the infection.

Infection: If there is an abscess or infection in the area, this could make the local anesthetic less effective due to the low ph. Occasionally sodium bicarbonate could to added to increase the ph in order to improve onset and quality of the nerve block. Another possibility is that the local anesthetic was not deposited close enough to the nerve to numb it or it was injected intravascularly.

See below: Sometimes with inflammation and infection the local anesthetic cannot penetrate to the nerve and so pain can still be felt. I am sorry this happened to you.