In the past, when we attempted Re-treatment, we used to re-treat all the canals. For the past 4-5 years, I’ve been doing mostly selective Re-treatment ie: treat only those roots or canals which need something to be done. Michael Trudeau calls it “Titrated Treatment”. Some of my friends on TDO call it “Image guided Treatment (IGT)”.
This is a Maxillary first molar treated several years ago and the patient came back with pain. CBCT shows missed MB2 with separate portal of exit. I located and treated only the MB2. Left the rest of the canals as they were.