Background and objectives: The primary oral disease during adolescence is dental caries. Less is known about the caries prevalence, oral health behavior, and sweets nutritional habits in Romanian adolescents. The objective of this study was to assess the actual caries prevalence among Romanian adolescents in a representative area of Romania, Cluj, and to correlate with oral hygiene behaviors and dietary sugary foods intake. Materials and methods: We have done a cross-sectional study of 650 adolescents aged 10 to 19-years-old (average age 15.3 ± 2.8). We performed the oral dental examination according to the WHO methodology, calculated the number of decayed, missing (due to caries), and filled teeth (DMFT index), assessed the oral hygiene and dietary behaviors using a two-section valid questionnaire and statistically analyzed the interrelation between DMFT, oral hygiene and eating behaviors by multivariate statistical analysis. Results: (a) The caries prevalence in the adolescent population enrolled in the study was 95.5%; (b) the mean DMFT was 3.13 ± 2.0, without significant differences between the urban and rural adolescents (p = 0.253); lower in females than males (p < 0.050), (c) more than one third (33.7%, n = 219) of teenagers are seldom or never brush their teeth in the evening; (c) 40.6% of adolescents are missing the regular annual dental check-ups leading to an increased DMFT as shown in the multivariate analysis (p = 0.038); and (d) there is an increased prevalence of caries with age (p = 0.020), and with sugary sweetened beverages consumption (p = 0.028). Conclusions: Our study evidenced a persistent high caries prevalence in Romanian teenagers. Their dietary habits and irregular dental check-up were associated with the occurrence of dental conditions.