Ask an Expert: Novocaine

Dental Anesthesia

Novocaine
07/24/2008

Question:

although a few physicians doubted the relationship of dental novacaine injection and the diagnosis of Bell`s Palsy 24 hours after the injection seems too coincidental. After viewing the facial nerves couldn`t there even be a remote possiblity that this could have happened?

Answer:

Thank you for your question. Although the two events are linked as being close in time, there is no evidence that Bell's Palsy is related to dental treatment directly. The nerves to the teeth and muscles and facial expression are actually different as you have no doubt found out: the fifth cranial nerve for jaw sensation and the seventh cranial nerve for the facial muscles. Although the exact cause for Bell's Palsy is not clear, it is presumed due to pressure on the course of the nerve through a very small bony canal. This would be unrelated to dentistry or local anesthesia.
If I extrapolate from relatively new information regarding pain processing in the central nervous system, one could theorize that surgery to the face, mouth or teeth might cause changes in the central nervous system that might somehow interact with these seventh nerve fibers such that a person who would develop Bells' Palsy might do so just at this time. The anatomy makes this relationship tenuous but if you were looking for a possible explanation, this is a theory.
Right now it seems that both things happened in close proximity time-wise and that is the only relationship. Also, the local anesthesia would have reduced the "risk" in my theory, but pain following the procedure would be the issue. This is all an intellectual stretch but if you are into researching on the computer, you might see things like this.

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Response by:

Steven I Ganzberg, SB, DMD, MS
Former Clinical Professor of Dentistry
College of Dentistry
The Ohio State University