Hi Elmhar, I've always had trouble getting numbed for dental appointments. I'd always just sort of "take it" vs. having more shots. Whether it was root canals, wisdom teeth, drilling etc.,. I've got a great dentist though though that works with me to ensure I'm numb before anything is started. I'd never really thought about it being a "Fibro" related thing since I can't remember not having this issue. But, I agree with BlueLakeLady who feels that Fibro patients tend to more sensitive to pain (since we experience so much pain in general) so it does make sense.
In general though I've heard that Fibro patients tend to have more teeth/gum issues than the general population & require more individualized care. There's a book by Flora Stay, DDS called the Fibromyalgia Dental Handbook that's really helpful.
But, definitely talk with your dentist & if they aren't helpful - find one who is.
Hope that helps!