It exhausts me to talk about it and no doubt folks here have already heard my story.
To be very brief, mine did start in the dental chair.
My story might be a little different in that I had NO pain to start with. I had an onlay (mini cap) fall off a tooth and I wanted it replaced because a big event was coming up in another city for me and I didn't want problems...was trying to be preventative.
The first dentist had freakish problems putting on a cap (she insisted on doing this instead of an onlay), which started the pain. Other dentists got involved and then I had more pain. Second dentist in the same practice put in a rod (post?) ...can't recall the term. I had electric type horrible pain at that point and started crying instantly and it was hard to keep from screaming.
Had other procedures...extreme extreme constant over the top pain! So, heck YES, I had UNNECESSARY procedures!!!!!!!!!!!
Even had my tooth pulled as one dentist insisted this would help. It did not help.
It's been about two years.
Finally, one oral surgeon (who has a dual degree in that he is an oral surgeon an also a M.D.) told me to see a neurologist.
I actually saw a few. All thought I had nerve damage caused from the dental work, likely from the early work. My pain is likely permanent. It is a horrid experience. I sometimes get nauseas from the pain. I use expensive medicine daily, multiple times a day to survive.
Dx: Atypical Trigeminal Neuralgia
CHOSE YOUR dENTIST CAREFULLY!!!!!!!! And don't hesitate to get a second opinion

BTW, after this happened to me, I was shocked to discover how many people with this problem had it start after a visit with the dentist. It is disturbing (I have other words I could use here) that dentists don't wish to learn more about it in order to take steps toward prevention, etc. CHOSE your DENTIST CAREFULLY!!!!