To investigate the prevalence of malocclusion in primary dentition among preschool children in Kunming. To analysze the relationship between malocclusion and oral bad habits, genetic factors and the caries prevalence in preschool children.

According to economic conditions and distribution area of Kunming school, a total of 2116 preschool children from nine kindergarten in Kunming city were surveyed. Oral examniation of 2116 preschool children were conducted by trained dentists to investigate the prevalence of malocclusion and the prevalence of dental caries in Kunming. A self-designed questionnaire was used to investigate the oral habits and genetic factors of the children in the study and to analyze the correlation between malocclusion and oral bad habits, genetic factors and caries rate of deciduous teeth.

Among the 2116 preschool children examined, 1516 were malocclusion, the prevalence of malocclusion was 71.64%, and the rate of dental caries was 63.50%. Bad habits and genetic factors were the risk factors of malocclusion, and there was no statistical difference in the prevalence of malocclusion between the tested children and those with or without caries.

The prevalence of malocclusion in the preschool children in Kunming city is high. The dentist is required to do the work of preventing bad habits. Parents need to improve the awareness of oral health care, together to do the early diagnosis of malocclusion, early diagnosis, early treatment.