Objective This study aims to investigate the caries status of the first permanent molar and primary tooth among 7-to 9-year-old children in Tangshan city and the correlation between caries of primary tooth and the first permanent molar.Methods A stratified cluster sampling method was used on the basis of the Basic Approach of Oral Health Survey of WHO and the Guideline of the Third National Oral Health Survey. A total of 10 primary schools were randomly sampled in clusters that included 51 primary school sampling spots in Tangshan. The caries status of 1 794 children aged 7 years to 9 years was examined.Results The prevalence rate of the first permanent molar caries was 47.49% (852/1 794), the mean number of DMFT was 1.30±1.59, the mean number of DMFS was 1.96±3.40, and the filling rate was only 2.35% (20/852). The prevalence rate and mean DMFT of the first permanent molar caries showed significant difference between different ages and genders (PConclusionCaries status of the first permanent molar among 7-to 9-year-old children in Tangshan city is serious. Caries status of primary tooth may play an important role in predicting the first permanent molar caries in clinic and prevention.
