REMINERALIZATION EFFICACY OF 1450 PPM SODIUM FLUORIDE ON A GROUP OF EARLY-STAGE CARIOUS PERMANENT TEETH IN CHILDREN AGED 6-15 YEARS ON NGOC VUNG ISLAND QUANG NINH PROVINCE IN 2025. YHCĐ. 2026;67(5). doi:10.52163/yhc.v67i5.5179