index of complexity outcome and need

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An index developed to assess orthodontic treatment complexity. It provides a summary score based on the severity of the malocclusion and the difficulty of the proposed treatment from an examination of the pre-treatment study models. It incorporates features of the Index of Orthodontic Treatment Need (IOTN) and the Peer Assessment Rating index (PAR). Occlusal traits are scored and multiplied by their respective weightings.A score of more than 43 is taken to indicate a demonstrable need for treatment. The index can be applied to the post-treatment models to assess treatment outcome; if the summary score is less than 31 the outcome may be considered to be acceptable.

ICON index variables

Occlusal trait

ICON index weighting

IOTN aesthetic component


Upper arch crowding/spacing




Overbite/open bite


Buccal segment relationship


Subjects: Dentistry.

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