Examination of the occurrence of dental caries and contributing factors in school-aged left-behind children in rural regions of Western China: a cross-sectional study

Dental caries remains a major public health concern among children in low-and middle-income countries, particularly in rural areas where preventive and restorative services are limited. In China, the growing population of left-behind children— those whose parents migrate for work— may be especially vulnerable to oral health inequalities. This study aimed to assess the prevalence of dental caries among left-behind and non-left-behind school-aged children in rural western China, to identify associated risk and protective factors, and to examine whether parental absence constituted a significant determinant of oral health. A cross-sectional survey was conducted among 1,613 school-aged children selected using stratified cluster random sampling. Oral examinations and structured questionnaires were employed to collect data on caries prevalence, dental fillings, and pit-and-fissure sealant application. Chi-square tests and multivariate logistic regression analyses were performed to identify factors influencing caries occurrence. The overall prevalence of dental caries was 93.37%. Left-behind children exhibited a higher prevalence (94.97%) than non-left-behind children (91.73%) (χ 2 = 6.83, p -value = 0.009). The filling rate was significantly lower among left-behind children (7.36%) compared to their peers (10.25%) (χ 2 = 3.91, p -value = 0.048), and the pit-and-fissure sealant rate was also lower (2.09% vs. 5.39%) (χ 2 = 12.28, p -value < 0.001). Logistic regression analysis identified female gender (OR = 2.933, 95% CI: 1.253–6.862) and non-use of fluoride toothpaste (OR = 3.416, 95% CI: 1.062–10.992) as significant risk factors, while regular or occasional fluoride use and adequate brushing duration served as protective factors ( p -value < 0.05). Dental caries prevalence among rural school-aged children in western China was found to be extremely high, irrespective of whether they are left-behind children. Left-behind children exhibited significantly lower access to restorative and preventive care, underscoring oral health inequalities. These results highlight the urgent need to strengthen preventive strategies and improve equitable access to dental services, with particular attention to left-behind children.