Associations between caries experience and oral fluid mineral content among patients in Arctic Russia: a study in the Nenets Autonomous Area

The relationship between the intensity of caries and mineral composition of oral fluid in adolescents in the Arctic zone of Russia was investigated using the example of the Nenets Autonomous Okrug. This study included 171 healthy boys and girls aged 15–17 years. The intensity of caries was assessed using the index caries + fillings + extracted permanent teeth and its components. Unstimulated oral fluid was collected into sterile tubes. Sodium, potassium, magnesium, phosphorus, and total and ionized calcium content and pH were examined in the oral fluid. Considering the pronounced right-sided asymmetry of the components of the index caries + fillings + extracted permanent teeth, calculations were performed using Poisson regression models. Results were presented as relative risks with 95% confidence intervals and as tests for trend. The prevalence of caries in the sample population did not differ by sex and was 87.8% for boys and 93.3% for girls (p = 0.221). On average, 1.8 carious teeth per person were detected in boys and 1.4 in girls (p = 0.021). No differences were found in the number of filled (p = 0.167) and extracted (p = 0.981) teeth. Additionally, the total sodium content in oral fluid was directly proportional to the index of caries + fillings + extracted permanent teeth (p = 0.040) and number of carious teeth (p < 0.001). The total oral fluid calcium was significantly associated with both the caries + fillings + extracted permanent teeth index (p = 0.019) and number of filled teeth (p = 0.001). Inverse relationships were found between the number of filled teeth and magnesium (p = 0.028) and phosphorus (p = 0.037) content. The study showed the presence of statistically significant relationships between the mineral composition of oral fluid and index of caries + fillings + extracted permanent teeth and its components. Thus, unfavorable living conditions in the Arctic zone provide additional risk factors for the occurrence of dental diseases. The results of the study, if confirmed in other populations, can be used to develop models for predicting the development and progression of caries in adolescents of the Far North. Further studies of the mineral composition of oral fluid are required to obtain more complete clinical and laboratory data, considering confounding factors such as nutrition and type of filling material.