Abstract: Objective: To investigate the caries status among 3-year-old children in Nanchong city from 2012 to 2014, and to evaluate and track the effectiveness of "comprehensive intervention program project of oral diseases of preschool children" after three years implementation. Methods: A sample that comprised 2567 3-year-old children attended "comprehensive intervention program project of oral diseases of preschool children" were examined at the baseline and 2 and 3 years follow-up. Caries were recorded using World Health Organization criteria. The control group comprised 1583 3-year-old children who didn't attended the project. The data were analyzed statistically by SPSS 23.0 software. Results: The incidence rates of caries in intervention group for 3 years were 68.5%,70.4% and 73.7%, and control group were 69.7%,76.7% and 85.1%, respectively. An increasing prevalence tendency was observed as the age increased (P<0.05).The incidence rate of caries intervention group was lower than that of control group (P<0.05). Conclusion: The prevalence of caries of 3-year-old children was high in Nanchong city. The effect of "comprehensive intervention program project of oral diseases of preschool children" is obvious.

Key words: Three-years old children, Primary caries, Epidemiological investigation , Comprehensive intervention program , Oral health education