A comparison and evaluation of the use of three orthodontic indices in assessing the treatment outcome

OBJECTIVE: To assess the differences in treatment outcome evaluation using the Dental Health Component (DHC) and Aesthetic Component (AC) of the Index of Orthodontic Treatment Need (IOTN), the Index of Complexity, Outcome and Need (ICON), and the Peer Assessment Rating (PAR), and to examine scoring agreement between orthodontic residents and undergraduate students. MATERIAL AND METHODS: A total of 87 study casts were assessed using the IOTN, ICON, and PAR indices to evaluate treatment outcome, with intra- and inter-examiner reliability examined. RESULTS: High to very high correlation was observed among AC, ICON, and PAR at T1 (p < 0.0001), while at T2, a high correlation was found between ICON and AC (p < 0.0001). Low correlations were found between DHC and both PAR and ICON. A negligible correlation was found between AC and DHC at T2. IOTN components showed good reproducibility at T1, whereas DHC, ICON, and PAR demonstrated moderate reliability at T2. Among orthodontic residents, ICON showed moderate (T1) and good (T2) reliability. PAR showed excellent reliability at T1. Among all examiners, all indices had moderate reliability at T1, and both ICON and PAR had poor reliability at T2. CONCLUSIONS: ICON was the most reliable index among orthodontic residents and required less scoring time than PAR, although IOTN remained the quickest to apply.