Prevalence of Malocclusion in 3- to 5-Year-Old Children in Shanghai, China

The aim of the present study was to obtain the prevalence of malocclusions in preschool children in Shanghai, China. A cross-sectional survey was conducted among 2335 children aged 3–5 years from kindergartens. Several occlusal parameters were clinically assessed, including second deciduous molar terminal plane, canine relationship, degree of overjet and overbite, anterior and posterior crossbite, and the presence or absence of physiologic spaces and crowding. All parents of subjects were asked to fill in the oral health knowledge questionnaires. The prevalence of malocclusion in primary dentition in Shanghai was 83.9%, and no significant differences were found in genders. Data showed that the prevalence of deep overbite (63.7%) was the highest in children with malocclusion, followed by deep overjet (33.9%), midline deviation (26.6%), anterior crossbite (8.0%) and anterior crowding (6.5%). The results revealed a high prevalence of malocclusion in primary dentition in children aged 3–5 years old of Shanghai, especially in vertical anomalies. The need for preventive orthodontic therapy is extremely desired and oral health education about malocclusion should be strengthened.