This is interesting to me (may be quite boring to others) but I know a few dentists log on here from time to time. This man was referred to our clinic with these x-rays in hand wanting to know if we could "guarantee" that we could save his 2nd Molar.
Mesial and distal canals seem straight but canal space disappears as you move apically. You can see a distal apical RL. Distal canal was accessed by previous dentist and filed to near WL.
Oooops. Hand file perforation into the furcation by previous dentist when searching for mesial canals. But recognized and patient was appropriately counseled.