Determinants of dental caries among primary schoolchildren in a mountainous region of Northern Vietnam.

Background: Tooth decay remains one of the most prevalent chronic conditions affecting children globally, especially in underserved populations. Despite growing international attention, limited data exist on the oral health status of children in remote regions of Vietnam. Objective: To assess factors associated with dental caries among primary schoolchildren in the mountainous province of northern Vietnam. Methods: A cross-sectional study was conducted from April 2024 to April 2025 among 545 children enrolled in four primary schools in Sa Pa, Lao Cai Province. Clinical dental examinations were performed using the International Caries Detection and Assessment System (ICDAS). Data on oral health behaviors and sociodemographic characteristics were collected via structured interviews. Descriptive statistics summarized the prevalence of caries and oral hygiene practices. Associations were analyzed using stepwise logistic and linear regression models. Results: The overall prevalence of dental caries was 91.4%, with 57.4% of children affected in permanent teeth and 82.2% in primary teeth. The mean DMFT and dmft scores were 1.31 and 5.38, respectively. Older age increased the risk of permanent caries but reduced primary caries and dmft scores. Significant disparities were observed by ethnicity, with Tay children showing higher odds of primary caries and Hmong children lower dmft scores compared to Dao peers. Children of non-farmer parents, particularly workers, had lower dmft scores than those of farmers. Frequent candy/snack and soda consumption were linked to higher primary caries, while poor brushing habits and symptomatic-only dental visits were associated with worse caries indices. Conclusions: Children in remote mountainous areas of Vietnam bear an alarmingly high burden of untreated tooth decay, particularly in primary teeth. Sociodemographic factors and inadequate oral health practices significantly contribute to this burden. Tailored, school-based preventive interventions, improved parental education, and enhanced access to dental care are urgently needed to address disparities and improve children's oral health outcomes in these regions.