Introduction: Negligence of the healthy behaviour associated with oral health, dental prevention and treatment in primary school children can be a source of serious health problems, both dental and systemic. Aim: The aim of this study was to evaluate the effects of selected demographic factors and reasons for visiting a dental office on the dental health of primary school children. Material and methods: The study included 210 patients aged 7–11 years, who in 2015 visited one of the dental offices in Lublin, where dental services are provided both under the contract with the National Health Fund or after payment. Dental condition was assessed by calculating dmf/DMF (decayed, missing, filled) index for deciduous/permanent teeth. Results: More than three-quarters of children (77.14%) visited a dentist for check-up, 20.0% – due to a toothache and 2.86% – due to the loss of filling. The average DMF number was 4.24 ± 3.47, and the average DMF index value was 1.74 ± 2.06. The highest intensity of caries in the primary teeth was found in children visiting the dentist due to toothache, lower – in those reporting for check-up visits and the lowest – due to the loss of filling. In the case of permanent dentition, the highest number of fillings was observed in children attending a check-up visit. Conclusions: High incidence of caries in primary school children confirms the insufficient health knowledge of parents/guardians on the oral health and insufficient dental prevention and treatment in both preschool and early-school children.