A 37-year-old patient complains of bleeding gums, bad breath, loose teeth, difficulties with chewing food. Objectively: gums are bluish-red in colour; periodontal pockets are 6 mm deep and contain serous substance; class II teeth mobility; moderate deposits of subgingival and supragingival dental calculus;OralHygiene Index equals 3 points; there is traumatical occlusuion along all the length of the dental arches. What is the provisional diagnosis?