[Epidemiological survey of malocclusion in 8-9 year-old children in Qingdao Laoshan district]

To investigate the prevalence of malocclusion and the correlation between caries and malocclusion in mixed dentition of primary students in Laoshan district of Qingdao city, to provide a scientific basis for early orthodontic treatment.

According to WHO's oral health survey (basic methods), a survey concerning oral health was performed in 1803 children aged 8-9 years old. SPSS 17.0 software package was used for statistical analysis .

1322 of 1803 pupils suffered from malocclusion, the prevalence of malocclusion in children surveyed was (73.32%). There were 519 cases(39.26%) of Class I malocclusion, 374 cases(28.29%) of Class II malocclusion, 357(27.00%) cases of Class III malocclusion, 72 cases (5.45%) with asymmetric malformation. As regard to clinical manifestations, deep overbite accounted for(37.67%) ,followed by deep overjet(29.19%), dental crowding (16.94%) and crossbite(16.03%). The prevalence of caries was 64.23%. Among them, there were 625 males (34.66%) and 532 females(29.51%).

The prevalence rate of malocclusion in mixed dentition of primary students in Laoshan district of Qingdao district is not optimistic, the incidence of malocclusion is closely related to caries.