Abstract:

 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 (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.

Key words: caries, the first permanent molar, primary tooth, correlation analysis