Expert: Steven C. Scherr, D.D.S. - 10/12/2007

Question
Hi, about a week ago i had a root canal and extraction done. When i went in for the procedure the infection that had come and gone twice before had come back. When he administered the Novocaine it was the most painful experience i have had at the dentist. it felt as if he had stabbed my tongue with a knife, the root canal and extraction went fine, not much pain afterwards really, taking antibiotics for the infection ect.. but what concerns me is that part of my tongue is still numb.. how long should i wait to see if it heals itself?

Answer
Joe,

Persistent numbness is a side effect of local anesthesia that occurs after a very small number of injections.  It is thought to be due to inadvertent trauma to the nerve from the needle.  During the injection, the dentist cannot directly see the nerve, and thus bases the placement of the needle on average anatomic landmarks.  The goal is to deposit the anesthetic solution near the nerve.  The anesthetic then spreads through the tissue until it reaches the nearby nerve.  Making a direct strike of the nerve with the sharp tip of the needle is like finding a "needle in a haystack".  Unfortunately, that is exactly what does happen every once in a great while.  Typically, a sharp, electrical pain is felt by the patient when this occurs.  Anesthesia is generally profound as the anesthetic couldn't be deposited any closer to the nerve.

Fortunately, the nerve usually will heal on its own and the numbness resolve within several days or weeks of the injury.  If it does not resolve within about 60 days, it is a good idea to at least visit a neurologist or neurosurgeon to see about possible surgical intervention for repair of the nerve.  Spontaneous resolution is still possible up until about the 6 month point.  However, when surgical intervention is warranted, the chance of success is dependent on early intervention.

Joe, I wish you my best.

Steve