TY JOUR TI METHODOLOGICAL PRINCIPLES OF TREATING CHEILITIS IN THE FAR NORTH KW various forms of cheilitis KW chronic recurrent fissure of the lip KW improvement of medical care KW Far North KW level of vitamin D and E in blood serum JO Actual problems in dentistry AU Isaeva, L.I. AU Borisova, E.G. AU Khrustaleva, Y.A. PY 2023 IS 19 PB TIRAZH Publishing House