Effects of Drinking Water Calcium, Magnesium, and Fluoride Concentrations on Dental Caries among Mongolian Children under 5 Year Old

Abstract: Dental caries remains a major public health challenge among children in Mongolia. The chemical composition of drinking water plays a crucial role in caries prevention. Fluoride influences the balance of enamel mineralization by forming fluorapatite on acid-exposed enamel surfaces, thereby reducing enamel solubility. Moreover, fluoride inhibits the acidogenic metabolism of cariogenic bacteria such as Streptococcus mutans within the dental biofilm. Therefore, understanding the relationship between drinking water, mineral content, and dental caries is essential for developing effective preventive strategies. Objective: To determine the prevalence and mean score of dental caries among children under 5 years old, covering 21 provinces of Mongolia, and to evaluate the effects of selected drinking water minerals (calcium, magnesium, and fluoride) on dental caries. This study utilized oral examination data from 118,153 children under 5 years old residing in 321 soums from all 21 provinces and the capital city (Ulaanbaatar) of Mongolia. Dental caries was assessed according to the World Health Organization (WHO) caries diagnostic criteria. The associations between drinking water mineral concentrations and dental caries were analyzed using linear regression models. The prevalence and mean score of dental caries ranged 63.5%-66.2% and 3.0-3.1 among 5-year-old children, respectively. Boys had a slightly higher score (3.17 ± 3.52) than girls (2.92 ± 3.40). Regression analysis revealed that fluoride (β = −0.449, p < 0.001) and magnesium (β = −0.031, p < 0.001) concentrations in drinking water were significantly associated with lower levels of dental caries, indicating a protective effect on dental caries. Fluoride and magnesium in drinking water appear to be important protective factors of dental caries, whereas calcium did not demonstrate a consistent association. These findings highlight the potential importance of drinking water mineral composition in the prevention of childhood dental caries in Mongolia.