Dentist referred me to a root canal specialist for my crowned upper molar, but it still hurt & abscessed 7 years later (Photo)

The tooth was pulled. There was considerable bone damage from the infection. Bone grafts were performed but the first implant failed, second so far successful. The root of the pulled tooth, photos attached, is atypical. Its counterpart on the other side had five canals rather than four. It is likely the specialist missed the fifth canal and the dying nerve caused the abscess. Is it reasonable to expect that he as a specialist should have detected & evacuated the nerve in the fifth canal? Thanks!