The last time I went to the dentist, thankfully, it was just a cleaning. Something came up in during the visit that may interest you, though.
I told my Dental Hygienist I had Atypical Trigeminal Neuralgi., she offered "something to make it kind of numb" if I had pain during the cleaning. I didn't require it.
She prescribed a pain killing mouthwash for me to fill, in case I had a "flair-up" afterwards. I did not have it filled. I didn't need it.
Your pain character could be more likely to be irritate by a dental procedure. My triggers are mostly chewing, talking, smiling and sometimes have LvL 8 pain, still, come on me without any triggers.
You can't compare my type of visit to yours, they weren't replacing a cap! But the pain-killing/easing options that the Hygienist mentioned may help you through this!
You have triggers inside your mouth and it is a dental procedure, not routine maintenance.
If I were you, I would call my destist's office before and tell them I need to discuss the fact that I have "Trigeminal Neuralgia with trigger points inside my mouth. Dental work could send me into excruciating pain". I would ask to speak to whomever would be performing my dental work, and discuss options for anything that may help me have an easier experien, due to the fact that I have a RARE condition!,
If you can speak with your dentist, I would ask what they can do to help (injections, numbing solutions) to stop triggers from happening for you. Chances are, you may be their ONLY TN patient. You are a special case for them, and should be treated as such, I believe.
I hope your dental appointment goes smooth, and that this helps.