European Journal of Molecular & Clinical Medicine ISSN 2515-8260 Volume 7, Issue 08, 2020 1316 Oral Health And Prevention Of Dental Caries In Preschool Children Living In Conditions Of Biogeochemical Fluorine Deficiency S.S. Murtazaev 1 , N.Sh. Akhrorkhujaev 2 , L. P. Kiselnikova 3 , J.A. Dinikulov 4 , M. M. Astanakulova 5 1 MD, Associate Professor, Head of the Department of Pediatric Therapeutic Dentistry, Tashkent State Dental Institute, Tashkent,Uzbekistan 2 External PhD student of the Department of Pediatric Therapeutic Dentistry, Tashkent State Dental Institute, Tashkent, Uzbekistan 3 MD, Professor, Head of the Department, Chief Freelance Specialist of the Moscow Department of Health on Pediatric Dentistry, Moscow, Russia 4 Assistant of the Department of Pediatric Therapeutic Dentistry, Tashkent State Dental Institute, Tashkent, Uzbekistan 5 Assistant of the Department of Theoretical Therapeutic Dentistry, Tashkent State Dental Institute, Tashkent, Uzbekistan ABSTRACT Research objective: to study the oral health and to work out preventive measures for preschool children living in conditionsof biogeochemical fluoride deficiency. Material and methods. The research included 280 children aged 4 to 6 years attending preschool educational institutions in the Kashkadarya and Surkhandarya regions. During the examination, the generally accepted sequence was followed: external examination, assessment of the teeth location, dentition, assessment of oral hygiene, study of the dental tissues. Besides, we determined and analyzed the quality of OHI, the PMA index, as well as applied methods for detection of concentration of fluoride in the oral cavity and the method of the detection of calcium and phosphorus in the oral fluid. Results and discussion. During the research the studies on the fluoride content in drinking water sources were carried out. It was established that the intensity index in the core group was 2 times higher than in the control group (P <0.001). Besides, the study showed that before the beginning of preventive measures, the concentration of hydrogen ions in the oral fluid of infants was 6.21 + 0.045, i.e. pH of the oral fluid had a shift towards the acidic side. A year after taking tablets with sodium fluoride, the concentration of hydrogen ions changed and made 7.07 + 0.029, and pH became neutral (p <0.001). Initial indicators of calcium in the oral fluid of children born and living in conditions of biogeochemical fluoride deficiency concluded 1.21±0.063 mmol/L, phosphorus - 1.86±0.043 mmol/L. The inclusion of “Fluorine balance” tablets in the menu of schoolchildren in a month led to a significant increase in the calcium content in the oral fluid to 1.47±0.056 mmol/L (p <0.01). After 2 months after the study initiation in the group to schoolchildren