Is there a way to undo novacaine? Yeah, sure, I mean they couldnt use it otherwise.
Novacaine costs about 20 cents a serving [I saw it in a dentist catalog].
You wouldnt want to undo it really cause you need some protection after the dentist did that work.
Wow, now I really appreciate the SuperEnamel I inherited from my mother. A month away from thirty, and never more than a cleaning at the dentist.
(Ducks to avoid jealous throwing of assorted mugs, pencils, assorted office supplies by SDMB members.)
Bite me. 
Congratulations on having won the tooth lottery. . . now, what kind of shape are your gums in?
As people get into their 30s and 40s, they often discover they have great teeth but really lousy gums.
Treatment for that is just as much fun as having your teeth worked on.
your humble TubaDiva