Examination of an 11-year-old boy revealed thickened, somewhat cyanotic, dense gingival margin overlapping the crowns of all teeth by 1/2 of their height. Fedorov-Volodkina oral hygiene index is 2,6, PMA index is 20%. X-ray picture shows no pathological changes of periodontium. The child has a 2-year history of neuropsychiatric treatment for epilepsy. Make a provisional diagnosis: