This patient appeared in my clinic with sinus tract and radiolucent area between mesial and distal root, Non surgical retreatment was done by myself about 18 months before the event. While taking an old root canal filling out MB and ML were joined by GG#3. On final the X-ray filling looked “wide” but there was no sign of perforation: no bleeding, no sealer’s puffs. So, tracing with GP leaded to furcation area.
It was clear that strip perforation on internal curve of mesial root caused that process. I decided to re-endo this case, to localize the perforation and to seal it if possible.
After calcium hydroxide was removed the whole canal volume was filled with MTA Angelus