Abstract: Abstract: Objective To investigate the first permanent molar status of primary-school students in Zhoushan City, as a reference for dental caries prevention and treatment. Methods The eruption out, nest ditch, and caries status of first permanent molars of 1035 second-grade students were inspected, recorded, classified and analyzed. Results Among the 1035 students inspected, 3345 first permanent molars had erupted, but 89 had no erupted first permanent molar with calculated eruption rate 91.4%. And 495 students were found to have one molar or several molars caries with calculated caries rate 47.8%. Conclusion The first-permanent-molar caries rate of Zhoushan City is significantly higher than the national average level, which is probably connected with geographical remoteness, traffic inconvenience, and local economical/cultural development level. In order to reduce the dental caries incidence and the effect of dental caries on children’s oral and mental health, it is very important to popularize oral health knowledge to local residents and improve their awareness of oral health.

Key words: first permanent molar , caries, caries prevalence rate