Comparison of the Discrepancy Index and the Index of Orthodontic Treatment Need
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Hypothesis: We hypothesize that there is a relationship between the American Board of Orthodontics (ABO) Discrepancy Index (DI) score and the Index of Orthodontic Treatment Need (IOTN). Objective: To test whether the Discrepancy Index and Index of Orthodontic Treatment Need can be interchangeably used for determining orthodontic treatment need and case complexity. Methods: 163 de-identified records of subjects in permanent dentition were scored based off of both indices. A complete set of records included intraoral photos, OrthoCAD® digital dental models, panoramic radiograph, and cephalometric radiograph. Results: There is a statistically significant difference between DI score values for IOTN=1 subjects compared to IOTN=2-5. There is no statistically significant difference between DI score amongst IOTN groups 2-5. Conclusions: The Discrepancy Index and Index of Orthodontic Treatment Need cannot reliably be used interchangeably except in cases with very minor malocclusions. A case that is scored as IOTN=5, indicating high need for orthodontic care, will not necessarily be scored as having high case complexity as measured by the Discrepancy Index.
SubjectAmerican Board of Orthodontics
Index of Orthodontic Treatment Need