This root canal was done just over four years ago. The patient presented with pain to percussion, and an 8 mm buccal probing was present. The RCT had been completed 2 years previously and recently became symptomatic.
Treatment recommended: Non-surgical retreatment, perforation repair with possible need for endodontic surgery. Prognosis: guarded.
As you can see, the MB canal is very calcified. Calcification of this kind would make this case a very high level of difficulty. The MB canal was missed and the furcation was found, instrumented & obturated. Proper case selection can help prevent this type of complication. However, if this does occur, one would expect to find bleeding and the tactile sensation of the pdl/cortical bone is very different from the canal. Length determination films, working films or final films should also identify the perforation. I would recommend immediate referral to an endodontist for treatment of an iatrogenic event such as this.
Retreatment completed. MB canal located and treated. Furcal perforation repaired with MTA. Patient placed on recall to watch the area and see if endodontic surgery will be required.
Recall at 2 years & 3 months. Patient reports complete function and no symptoms. The 8mm periodontal probing has dissappeared. This tooth is considered "healing", and scheduled for a 1 year recall.
You can call it "herodontics", but that tooth is functional, apical bone looks good, periodontal pocket has disappeared. This will be a fun case to watch over time.