[Caries status of the first permanent molar among 7- to 9-year-old children in Tangshan city and their correlation].

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 preva- lence rate and mean DMFT of the first permanent molar caries showed significant difference between different ages and genders (P < 0.05). However, the mean DMFS of the first permanent molar caries only showed significant difference between the various ages (P < 0.05). The prevalence rate of the primary tooth caries was 83.11% (1 491/1 794), the mean number of dmft was 4.82 +/- 3.55, the mean number of dmfs was 6.51 +/- 5.61, and the filling rate was 12.41% (185/1 491). Caries of primary tooth was the first permanent molar caries risk factor [r = 0.277, OR = 5.736, P = 0.00, 95% CI (4.175, 7.881)]. Significant correlation was found between the caries of primary tooth and first permanent molar (r = 0.274, P < 0.001). CONCLUSION: Caries 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.