A 35-year-old woman with a history of pulp canal obliteration (PCO) and apical periodontitis was treated with guided endodontics combined with antimicrobial photodynamic therapy (aPDT). The use of aPDT was paramount to the approach performed, and its application should be encouraged in cases of severely calcified canals when apical patency is unachievable. The combination of these techniques ensured successful clinical, radiographic, and tomographic outcomes at the 1-year follow-up.