Aims: The aim of this study was to determine the orthodontic treatment needs in nine-year-old Valencian children using two internationally accepted and well-recognized indexes: the Dental Aesthetic Index (DAI) and the Index of Orthodontic Treatment Need (IOTN). Study design: A cross-sectional epidemiological study was conducted in a sample of 170 nine-year-old children in order to find the orthodontic treatment need according to the Dental Aesthetic Index and the Index of Orthodontic Treatment Need. Results: Orthodontic treatment was required by 48.8% of the sample according to the Dental Aesthetic Index: 19.4% had no need of orthodontic treatment, treatment was elective for 31.8%, desirable for 24.7% and necessary for 24.1% of the sample. According to the Dental Health Component and the Aesthetic Component of the Index of Orthodontic Treatment Need, orthodontic treatment need was required by 18.8 and 11.2% of the sample, respectively. The most common features of malocclusion in the sample were incomplete class II molar relationship, increased overjet and overbite and crowding. Conclusions: The need for orthodontic treatment in nine-year-old children is between 18.8 and 48.8% according to both indexes. The results obtained with both indexes are remarkably different, possibly because the Dental Aesthetic Index gives too much emphasis to some features of malocclusion that are transitory in mixed dentition, such as overjet, overbite, and molar relationship, which could result in an overestimation of orthodontic treatment need in mixed dentition.
(Rev Esp Ortod. 2015;45(1):007-012)