Objective To survey the tooth decay of the first molars among the people in area of northeast China in order to provide the foundation for prevention and treatment strategies of caries. Methods According to the third national oral health investigation of epidemiology, the dental caries of first permanent molars were examined among 9 394 people aged 5, 12, 35- 44 and 65- 74 in northeast China. The data were analyzed by SPSS13.0 statistical software. Dental caries prevalence rate and DMFT（dmft）of first permanent molar were calculated. Results The prevalence of crown and root dental caries in northeast China were 26.86% and 3.81% respectively, mean DMFT（dmft） of crown and root dental caries were 0.41 and 0.04 respectively. There were significant differences of dental caries among provinces in northeast China. Mandibular first molar suffered from dental caries easily. The prevalence of caries of female was higher than that of male（P0.05）. Except Jilin province, there were significant differences of prevalence of crown caries between city and rural area in Liaoning and Heilongjiang provinces（P0.05）. Conclusion The prevalence of dental caries of the first molar among the people in northeast China is high. The dental caries prevention and cure of first permanent molar should be emphasized in oral health field.
