摘要:(1) Background: Dental caries is a chronic disease that affects a child’s dentition from the first stages of life. Several factors contribute to the development of the disease, including an improper diet. This cross-sectional study aimed to identify risk factors of dental caries in 12-year-old adolescents from Greater Poland and Lubusz Provinces (Poland). (2) Material and methods: The research was conducted in adolescents from five primary schools. A questionnaire consisted of close-ended questions on socioeconomic characteristics on family, diet, and oral hygiene habits. An assessment of the dentition was carried out in accordance with World Health Organization (WHO) recommendations. In addition to cavitated carious lesions, incipient caries lesions were noted according to the International Caries Detection and Assessment System, adapted for epidemiological studies (ICDASepiDMFt). (3) Results: The mean number of teeth with untreated caries; removed due to caries; and restored because of caries (DMFt) was 1.52 ± 1.90, while the ICDASepiDMFt index amounted to 2.64 ± 2.55, respectively. Children who did not brush every day had significantly higher odds of having ICDASepiDMFt > 0 than children brushing at least once daily (OR = 10.32, 95% CI = 1.36–78.32, p = 0.0240). Adolescents who drank sweet carbonated drinks every day had significantly higher ICDASepiDMTt than children who drank sweet carbonated drinks less frequently (p = 0.0477). (4) Conclusions: The research revealed that dental caries indices of 12-year-old adolescents from Greater Poland and Lubusz Provinces depend mainly on oral hygiene behaviors. The only significant nutritional factor that differentiated the caries intensity was the daily consumption of sweet carbonated drinks.