This was an old case i discovered on my comp. I treated this case in 2006. It is probably a good case to demonstrate the location of the middle mesial canal.
Strangely, the first thing that I thought when I saw this case today was, “Did this really benefit the patient? There wasn’t any lesion and the patient didn’t have any pain. Did my over-enlarging the canals through re-treatment actually weaken the tooth and therefore the long-term prognosis? I probably would have thought twice about re-treating this today.