A 27-year-old patient complains of bleeding, pain and swelling of gums, tooth mobility, halitosis, general weakness. Objectively: submandibular lymph nodes are enlarged and painful, gums are hyperemic and cyanotic, they are also swollen and bleed at probing, periodontal pockets are 5-8 mm deep and contain sero-purulent exudate. There is massive dental deposit, gingival recession and tooth migration. X-ray picture shows diffuse osteoporosis and irregular, predominantly vertical, resorption of alveolar septa down to 2/3 of root length. What is the most likely diagnosis?