TY JOUR TI ANALYSIS OF COMPLICATIONS OF PERIODONTAL COMPLEX TISSUES THAT OCCUR AT THE STAGES OF ORTHOPEDIC TREATMENT (LITERATURE REVIEW) KW gingival retraction KW mechanical gingival retraction KW chemical gingival retraction KW tooth preparation KW removable dentures KW oral mucosa injury KW gingival recession KW bridge prostheses JO Actual problems in dentistry AU Knyshova, S.A. AU Lapina, N.V. AU Ovcharenko, E.S. PY 2026 IS 2021 PB TIRAZH Publishing House