This paper aims to report a single-session endodontic treatment of a periapical lesion, while highlighting the effectiveness and safety of the technique. The patient presented with no painful symptoms at the clinic to have his maxillary anterior teeth examined due to trauma suffered two years earlier. Radiographic examination revealed a lesion in the apical periodontium, extending from the region of tooth #13 to tooth #23. The teeth were isolated, and access surgery was performed in all crowns. Cleaning and shaping (6% NaOCl) were carried out with Gattes-Glidden drills with step-back instrumentation from #2 to #4. Catheterization was performed with manual files #25 up to the working length (6% NaOCl), and confirmed with foramen locator. Cleaning and shaping of all root canals were performed with the aid of ProTapers F4 and F5 instruments (Dentisply/Maillefer) (6% NaOCl).Passive ultrasonic irrigation was performed for 3 minutes in each tooth with continuous irrigation of 17% EDTA and Irrisonic ultrasonic insert (Helse). Final irrigation with 6% NaOCl and drying with paper points were performed. There was placement of methylene blue at 0.05% for 5 minutes on each tooth, followed by laser application (photodynamic therapy) for 80 seconds on each tooth. New irrigation with 6% NaOCl was carried out to remove the remaining methylene blue. Drying with paper points was performed for a second time, followed by filling with gutta-percha ProTapers F5 cones thermoplasticized with gutta-percha condenser #60 and AHPlus paste. In checking the conditions two years later, it was found that the procedure had been performed with integrity, thereby confirming the success of single-session endodontic treatment of infected root canals.Keywords: Endodontics. Root canal therapy. Odontoplasty. How to cite this article: Braitt AH, Santos JL, Braitt GR, Rodrigues EA, Bueno CES. Single-session endodontic treatment of six teeth with extensive periapical lesion.