A 54-year-old male patient complains about progressing pain in the area of upper jaw on the left that first arose 3 days ago. Body temperature is up to 37, 2°C. Objectively: gingival mucous membrane is edematic, hyperemic, it bleeds slightly. Parodontal pouches are 6-7 mm deep and contain a small amount of purulent exudate. A painful infiltrate is palpated in the region of the 26 tooth. The 26 tooth has III-degree mobility, the rest of teeth have I-II-degree mobility. X-ray picture shows resorption of interalveolar septa by 2/3 of root length. What is the most appropriate treatment method of the 26 tooth?