The quality of oral health can be estimated by its own indicators, one of which is the Decayed-Missing-Filled index (DMF-T for permanent teeth and dmf-t for deciduous teeth index). Caries can be prevented and successfully controlled by comparing clinical and epidemiological data. The basic prerequisite for this approach is data collection through systematic examinations, the results of which are a starting point for a prevention programme. The aim of the study is to define the oral health of elementary schoolchildren in one municipality of Slovenia, focusing on 6-, 12- and 15-year-old children. A prospective epidemiological study of elementary school children (aged 6, 12 and 15) of municipality Murska Sobota, Slovenia, was performed over four years. Data were obtained from the dental records of elementary schoolchildren acquired from a specialist in paediatric dentistry. Collected data included age, gender, the number of carious teeth and tooth fillings per child in deciduous and permanent teeth, dmf-t/DMF-T index and the percentage of primary and secondary healthy children. Statistical analysis was performed using SPPS 25. Data from schoolchildren were used (1256 girls, 1281 boys). The number of carious deciduous teeth per person in 6-year-olds (3.2-3.8) was higher than the number of (carious) permanent teeth in 12-year-olds (0.3-1.2). The number of filings per person in deciduous teeth in 6-year-olds (0.5-0.6) was lower than it was in permanent teeth in 12-year-olds (0.3-1.2). Dmf-t index in 6-year-olds was from 4 to 4.6; DMF-T index in 12-year-olds were from 1.2 to 2.2 and in 15-year-olds from 2.4 to 3.8. The percentage of primary healthy children was lower for older children, but the percentage of secondary healthy children was higher for older children. Monitoring oral health is important, and school has an important role in it; however, caries control has yet to be successful.