Prevalence and Influencing Factors of Mixed Dentition Malocclusion in Children Aged 6-12 Years in Jinzhou, China

Purpose: To investigate the prevalence, clinical manifestations and related risk factors of malocclusion in schoolchildren of Jinzhou City, China.Materials and Methods: A total of 2162 children aged 6-12 years were randomly selected from various districts of Jinzhou. Conventional clinical examination was performed by stomatologists, and the results were described based on different clinical manifestations of malocclusion and individual normal occlusion. Further, a questionnaire survey com-pleted by children's parents or guardians provided the demographic data, lifestyle, and oral habits. The distribution of in-dividual normal occlusion and malocclusion was documented in percentage, and Pearson's X2 was used for two-factor analysis. The data were statistically analysed using SPSS software (version 25.0) with a significance level of a= 0.05.Results: A total of 1129 boys and 1033 girls were included in this study, i.e. 52.2% and 47.8% of the total number of chil-dren, respectively. The prevalence of malocclusion in children aged 6-12 years old in Jinzhou was 67.9%, of which crowded dentition was the most common form, with a prevalence of 71.8%, followed by deep overbite, anterior crossbite, dental spacing, deep overjet, anterior edge-to-edge occlusion, and anterior open bite. In the logistic regression model, the results showed that BMI index had little effect on the occurrence of malocclusion (p>0.05), while dental caries, bad oral habits, retained primary teeth, and a low labial frenum were all related to the occurrence of malocclusion (p<0.05). Moreover, the higher frequency and duration of bad oral habits were associated with a higher likelihood of malocclusion.Conclusions: The prevalence of malocclusion in children aged 6-12 years in Jinzhou is high. In addition, bad oral habits (such as lip biting, tongue thrusting, biting/gnawing objects, unilateral chin supporting, and unilateral mastication) and other related risk factors (such as dental caries, mouth breathing, retention of primary teeth, and low labial frenum, etc) were associated with malocclusion.