A 40-year-old patient complains about a long-existing fissure in the central part of red border of his lower lip. He has been smoking since he was 16. Objectively: there is a deep 1,0 cm long fissure along the median line of red border of the lower lip, the fissure edges are bulging. Characteristic quality of the fissure is its spontaneous healing, but after epi-thelization the fissure recurs. The patient was diagnosed with chronic fissure of the lower lip. Conservative treatment proved to be ineffective. Choose the most appropriate treatment method in this situation: