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.

The sanitation of the canal system through irrigation/aspiration, at the changing of the endodontic instruments aims to the excised material, removal of microorganisms and the cleaning of the walls of the canals. One of the substances used in endodontic treatment of root canals, sodium hypochlorite, used at different concentrations of active chlorine and pH, has gained popularity due to its physical chemical properties. Objective: To analyze the active chlorine content of sodium hypochlorite solution at 6.0%. Material and methods: 80 samples were obtained from two litres of sodium hypochlorite at 6%, obtained at every hour: one liter was stored at room temperature and one liter at refrigerated environment, between the morning and afternoon shifts, except on Saturday and Sunday. The free residual chlorine was determined, using as variables: the temperature, length of time in storage and the handling of the substance in the Endodontic clinic for seven days. The data obtained were submitted to analysis of variance according to the linear regression model to test the effect of time of storage condition and interaction between the main effects on the chlorine content of the stocked solution (p < 0.01). Results: The results showed that the sodium hypochlorite solution is quite unstable, with considerable loss of active chlorine (58.33%), depending on the storage conditions and storage time and temperature. The temperature interferes in the free residual chlorine concentration contained in sodium hypochlorite solution, that is, the higher the temperature, the lower the lifetime of free residual chlorine in sodium hypochlorite solutions. Conclusion: Storage in refrigerated environment proved to be the best option to avoid the marked loss of active chlorine in sodium hypochlorite of concentration at 6%.

The use of a suitable irrigation solution and a correct root system shape effectively contributes to the success of endodontic treatment. Among the irrigating solutions used in Endodontics, sodium hypochlorite has been the most used because of many qualities. However, this substance must have chemical stability of its properties, by maintaining the potential of hydrogen (pH) and chlorine concentrations appropriately. Objective: The aim of this study was to evaluate active chlorine releasing and pH of some sodium hypochlorite solutions used in endodontic clinical practice. Material and methods: The solutions tested in this study were 0.5% Dakin, 1% Milton, 2% Chlorinated Soda, and household bleaches (Brilux®and Qboa®), which were opened at the same period and first used, with the same storage modus but with different manufacturing dates. The pH was measured with a digital device, and the active chlorine content was obtained through iodometric titration. Results:All solutions presented chlorine content not smaller than that informed in the flasks, ranging from 1% to 2.4%; pH was higher in all solutions, between 9 and 13. Conclusion: Based on the method applied and the results obtained, it was possible to conclude that sodium hypochlorite solutions used specifically in Dentistry (Dakin and Milton solutions and Chlorinated Soda), showed on the labels the hypochlorite content. On the other hand, household bleaches (Brilux® and Qboa®) showed the chlorine content. It was not possible to compare pH authenticity, due to lack of description on the label.