I would advise you to talk to your dentist beforehand.. theres a big chance of spread if you don't take precautions, here are some of the ones I follow since researching it.
)1 pre sedation ie: atavan 1 hr prior or laughing gas durring. not so essential.
)2 numbing cream used before first needle punctures. not so essential
)3 freeze very well before AND AFTER the procedure is done. VERY IMPORTANT!
)4 limit the time of dental work each visit. all at once is not good. Important.
Some don't follow all 4 but #)3 is very important to do at the least because you want to keep the area as painless and relaxed as possible soas not to irratate (wake up) the sympathetic nerves in the face.
For a root canal I would do all 4.. actualy I would not do the root canal.. thats already messin with the nerves.. If it was me I'd get the dentist to just pull it.. but thats me.
Have you discussed your condition at all to the dentist CB?