[Orthodontic treatment need: the IOTN, or Index of Orthodontic Treatment Need (part 2)].

IOTN is an index of orthodontic treatment need that has been devised on the basis of the available evidences of the deleterious effects of malocclusion on the aesthetic and health of the dentition. It has two components i.e. an aesthetic component and a dental health component. This index is widely used in epidemiological research and by third party payment for determination of those patients who should benefit from public funding.