A 28-year-old patient complains of pain and bleeding of gums in the frontal part of the upper jaw on the left. Two years ago, the 22 tooth was covered with a porcelain-fused-to- metal crown. Objectively: interdental papilla between the 21 and 22 tooth is hypertrophied, markedly hyperemic, overlaps the crown of the 22 by 1/3 of its height, bleeds when touched. Periodontal pocket between the 21 and 22 tooth is 4 mm deep. Artificial crown is placed on the gingival margin. X-ray reveals resorption of the interalveolar septa between the 21 and 22 tooth by 1/3 of their height. Specify a priority action in the treatment of this patient: