TY JOUR TI COMPARATIVE STUDY OF THE MICROHARDNESS OF RUSSIAN AND FOREIGN CAD/CAM COMPOSITE BLOCKS FOR THE MANUFACTURE OF CROWNS KW CAD/CAM materials KW composite crowns KW microhardness KW comparative study KW dental materials KW Russian composite KW Vickers method JO Actual problems in dentistry AU Vahobov, A.S. AU Vafin, S.M. PY 2026 IS 2021 PB TIRAZH Publishing House