can't go numb at the dentists

* need to see: Oral and Maxillofacial surgery with(medical, and surgical knowledge) * root canal specialist (endodontist) specialist *dental specialists (Prosthodontists)- can't go numb at the dentists with a max of local anaesthetics injection - can't go numb at the dentist's as I believe this is a (genetic ) my brother and my father was like that. - always feel pain in the teeth never had peace - some doctor said you have smallmouth maybe - some doctor said maybe your teeth haven't removed from the root - dr said maybe the root canal hasn't done well