A comparative study using the Occlusal Index and the Index of Orthodontic Treatment Need.

Assessment of malocclusion is important for documentation of the prevalence and severity of malocclusion in population groups. Such information is needed in Hong Kong where less than 25 qualified orthodontists serve a population of about 6 million citizens. The objective of the present study was to compare the Occlusal Index (OI) and the Index of Orthodontic Treatment Need (IOTN) when used to assess orthodontic treatment needs in a local population. Only a weak association (Spearman's correlation coefficient = 0.31) was found between the two indices. The shortcomings of both indices are discussed. Neither OI nor the IOTN is perfect, but using the IOTN is less time consuming, making the study of a large population group more practical.