Agreement between the index of complexity, outcome, and need and the dental and aesthetic components of the index of orthodontic treatment need

Introduction: This was a cross-sectional study to investigate the agreement between assessments of orthodontic treatment need of the index of complexity, outcome, and need (ICON) and the index of orthodontic treatment need (IOTN). Methods: Five hundred two subjects (253 girls, 249 boys; ages, 11-14 years) participated in this study, including a few who were wearing an orthodontic appliance (1 girl, 5 boys). ICON scores and the aesthetic (AC) and dental health components (DHC) of the IOTN were recorded in those not undergoing treatment. The percentages of subjects needing treatment (ICON score > 43) and the different complexity components of ICON were compared between the sexes. Observed percentages of agreement and kappa statistics were used to analyze the agreement between the AC and DHC of the IOTN and also the ICON, and the DHC and AC of the IOTN dichotomized into a yes or no categories of orthodontic treatment need. Results: No sex differences were found between male and female subjects for treatment need (ICON score > 43; P > 0.05) and treatment complexity (P > 0.05). The kappa statistic for diagnostic agreement between the DHC and AC of the IOTN was 0.55 (95% CI, 0.48-0.63). The kappa statistics for diagnostic agreement between the ICON and the AC and the DHC of the IOTN were 0.40 (95% CI, 0.33-0.46) and 0.78 (95% CI, 0.73-0.83), respectively. The observed agreement between the DHC and the AC of the IOTN was 81.8%. The observed agreement between the ICON and AC and DHC of the IOTN were 71.3% and 89.5%, respectively. Conclusions: In terms of orthodontic treatment need, there was moderate agreement between the ICON and the AC (IOTN), and between the DHC and the AC. There was good agreement between the ICON and the DHC of the IOTN. The ICON is a good substitute for the DHC of the IOTN. (Am J Orthod Dentofacial Orthop 2011;140:233-8)