Abstract
BACKGROUND: From 2005 to 2015, the prevalence of dental caries in both primary and permanent dentitions was significantly increased in China. Previous studies have shown that the prevalence of permanent dental caries in school-aged children had already reached 19.7%-54.0%, 97.5% affecting first permanent molars. This study aimed to investigate the prevalence and contributing factors of dental caries in 6-year-old children in four regions of China to provide information for oral health promotion programs. METHODS: A randomized cluster sampling method was employed in the study. All 6-year-old first grade children from the selected schools were invited to receive a clinical oral examination. Dental caries were diagnosed according to the World Health Organization criteria. The erupting first permanent molars were recorded using the modified International Caries Detection Assessment System. Questionnaires assessing children's oral health-related behaviors and their caretakers' oral health awareness and attitudes were completed by the children's parents or guardians. RESULTS: Overall, 4,936 6-year-old school children participated in the survey. The prevalence of caries among these children was 87.7%, with a mean number of decayed, missing and filled teeth of 6.04 (SD, 4.24). In primary dentition, the caries prevalence was 87.7%, and the mean dmft score was 6.01 (SD, 4.22). In permanent dentition, the caries prevalence was 2.0%, the mean DFS score was 0.04 (SD, 0.31). All permanent dental caries occurred on the first permanent molars. Carious tooth surfaces were identified as modified ICDAS code "A" to indicate initial caries and distinct visual change in enamel. The mean D(A)S score of non-cavitated caries in the first permanent molars was 0.18 (SD, 0.67). Logistic regression analysis showed that regional and gender factors were significantly related to the caries experience of these children. CONCLUSIONS: The 6-year-old children from four regions of China had sever primary dental caries and the first permanent molars were at high risk for dental caries. It is critical to protect permanent teeth from caries as early as the eruption of the first permanent molars.