The influence of eco-pathogenic factors on mineralization of teeth hard tissues at early age was studied in 525 young children, 3 to 4 of ages. Tooth caries index was detected according to the indexes provided by WHO (World Health Organization): prevalence, intensity (dmf) and Significant Index of Caries (SIC). The studies revealed that the average rate of dental caries for studied group living in regions with ecologically favorable conditions is relatively lower than in ones living in regions with unfavorable conditions and equals to 39.6% and 63.6%, respectively. Comparative analysis of average and significant indexes ​ of dental caries showed that the difference is minimal in children population living in favorable conditions (1: 1.7) in comparison with the children living in ecologically contaminated regions, where the significant index exceeds the average one approximately three times as much. According to the obtained results, it should be concluded that the dynamics of dental caries is mostly expressed in young children living in regions where air-pollution (with chemically aggressive substances) index several times exceeds the maximum allowable coefficient. Consequently, development and implementation of the special programs for caries-prevention in children population with low rate of caries-resistance, living in the above-mentioned conditions is of great importance.