A validation study of three indexes of orthodontic treatment need in the United States

The purpose of this study was to compare the reliability and validity of three occlusal indexes of orthodontic treatment need in predicting the opinion of treatment need of a panel of 18 orthodontists. A set of 160 study casts representing all types of malocclusion was used. The casts were scored with the following occlusal indexes: the Index of Orthodontic Treatment Need (IOTN), the Handicapping Labio-Lingual Deviations index (HLD), and the Handicapping Malocclusion Assessment Record (HMAR modified). The diagnostic accuracy or validity of each index was calculated using the mean opinion of the orthodontic raters as a "gold standard". Receiver Operating Characteristic curves were plotted for each index. The overall diagnostic accuracy, as determined by percent area under the curve, was similar for each index: IOTN 98.6%; HLD 96.1%; HMAR 96.6%. The score optimizing the sensitivity and specificity relationship for each index was as follows: IOTN (dental health component) 4; HLD 13; HMAR 12. These results indicate that the three occlusal indexes provided valuable information for determining orthodontic treatment need.