Assessment of Inter-Rater and Intra-Rater Reliability of Index of Orthodontic Treatment Need Index by Newly Trained Orthodontic Residents

Abstract

Introduction: This study aimed to test the reliability of the index of treatment need by newly trained orthodontic residents. Materials and Methods: A total of 100 patients were assessed by the panel of four consultant orthodontists using the index of orthodontic treatment need (IOTN) index, and the agreed category was set as the 'gold standard'. Four residents of the department in the initial stages of formal orthodontic training and lacking the knowledge of using the IOTN index were trained to score the treatment need according to the IOTN index. All four residents were then asked to score the 100 sets of models using both the indexes of IOTN. Results: Kappa scores for inter-rater agreement with the expert panel for the major categories (1–4) demonstrated moderate agreement (kappa: 0.59–0.5623) for all raters. The percentage agreement ranged from 84.03% to 88.10% in all cases. Intra-rater agreement for the major categories was fair to moderate (kappa: 0.53–0.80). Conclusions: The IOTN index is a reliable index to be used for determining the priority of treatment needs in orthodontic treatment. The clarity and simplicity make the index easy to learn and apply with minimal training. The simplicity of the IOTN index makes it easy to learn and apply by novices.