The question comes to mind...did this pain start only after your visit to the dentist? If you had some serious work done at the dentist with difficult procedures it would make sense, to me (though I am no doctor nor a dentist) that some facial nerves may have been disturbed.

I, too, would suggest getting a second opinion from a Neurologist. In the meantime, keep a journal of when and where the pain begins and ends, what you use to relieve the pain. Like, does it begin in the forehead and work down toward your jaw or is it all over all the time? Take these notes with you to the new dr. Just a suggestion, but it helped my neurologist rule out TN for me.