Abstract: Objective　To investigate the regularities of caries distribution in the primary dentition of children in Nanjing, China. Methods　449 children of 2 to 6 years old in Nanjing were selected for oral examination. Regularities of caries distribution on different tooth surfaces were analyzed. Results　The distribution of caries was bilateral symmetrical. The caries concentrated on the mesial surface of the maxillary primary central incisor, followed by the proximal and occlusal surface of the primary molar, and the labial and proximal surface of the maxillary primary anterior teeth. The risk of caries in primary anterior tooth surface increased towards midline; in primary molars, caries risk was higher in mandible than that in maxilla. There was higher risk of occlusal caries surface in second primary molars, and higher risk of proximal caries surface in first primary molars than that in second primary molars. Conclusion　The primary tooth caries distribution has specificity in tooth surface. The caries risk of tooth surface with similar appearance and adjacent position may be different. Prevention and treatment should be strengthened on the tooth surface with high caries risks.

Key words: primary dental caries, dmfs, distribution, tooth surface