Prevalence and associated factors of dental caries among preschool children aged 3 to 6 years in urban area of Shiyan City, China

Dental caries is a prevalent chronic disease in preschool children, with a particularly high burden in central and western China. This cross-sectional study sampled preschool children aged 3 to 6 years in urban Shiyan City using stratified random cluster sampling. Oral examinations followed the Fourth National Oral Health Epidemiological Survey of China and WHO criteria, using the dmft index for caries severity assessment. Parents completed a structured questionnaire covering oral health habits, dietary patterns, and socioeconomic status. The study was approved by the Ethics Committee of Taihe Hospital (Approval No. TH-2023-089). Chi-square tests and multivariable logistic regression were used to identify associated factors, and model performance was assessed via ROC curve analysis. All statistical analyses used SPSS 28.0, with data double-entered in EpiData 3.1. Among 1,989 children, caries prevalence was 63.2%, with a mean dmft of 3.42 ± 2.87, lower than the national average for 5-year-olds. Prevalence increased significantly with age, from 48.8% at 3 years to 72.8% at 6 years ( P < 0.001). A slightly higher prevalence was observed in boys than in girls (64.8% vs. 61.5%), though the difference was not statistically significant. Primary molars were the most frequently affected teeth (64.2%), followed by maxillary primary incisors (21.7%). Multivariable analysis identified several independent risk factors: bedtime eating/nocturnal feeding (OR = 2.48, 95% CI: 2.05–3.01), frequent sweets or SSB consumption (OR = 2.15, 95% CI: 1.78–2.61), delayed toothbrushing initiation ≥ 3 years (OR = 1.72, 95% CI: 1.42–2.09), lack of parental supervision (OR = 1.58, 95% CI: 1.30–1.93), lower parental education (OR = 1.44, 95% CI: 1.20–1.73), non-use of fluoride toothpaste (OR = 1.39, 95% CI: 1.16–1.67), and no dental visit in the past year (OR = 1.31, 95% CI: 1.07–1.60). Brushing twice or more daily was protective (OR = 0.68, 95% CI: 0.56–0.84). The model showed moderate discriminative ability (AUC = 0.78, 95% CI: 0.76–0.80). Preschool children in urban Shiyan City have a high caries burden with a clear age-related increase. Associated factors included unfavorable dietary habits, inadequate oral hygiene, low parental education, and infrequent use of oral health services. A predictive model incorporating behavioural and socioeconomic factors showed moderate discriminative performance (AUC ≈ 0.78), providing a potential tool for early risk stratification at the population level.