The application of the Index of Orthognathic Functional Treatment Need (IOFTN): service evaluation and impact.

OBJECTIVES: (1) To undertake a service evaluation of the Index of Orthognathic Functional Treatment Need (IOFTN). (2) To determine its suitability to replace the Index of Orthodontic Treatment Need (IOTN) in the assessment of patients with dentofacial deformity.

DESIGN: Laboratory- and questionnaire-based study.

SETTING: UK hospital-based orthodontic department.

METHODS: Cohen's Kappa was used to assess inter- and intra-operator reliability for the IOTN and the IOFTN against 30 orthognathic patients' models scored to a 'gold standard'. Questionnaires gathered feedback on ease of use of the IOFTN. Change in treatment need status for a further 60 orthognathic patients was estimated utilising the IOTN, the IOFTN and a modified IOTN (mIOTN).

RESULTS: Inter-operator agreement with the 'gold standard' for the IOTN and the IOFTN ranged from 0.64-0.90 and 0.61-0.91, respectively. Intra-operator agreement for the IOTN and the IOFTN ranged from 0.46-1.00 to 0.59-0.95, respectively. Mean feedback score was 9.08 out of a maximum score of 10. Overall, 88.9% of patients scored grades 4 or 5 on the IOFTN (IOTN = 87.8%; mIOTN = 77.8%).

CONCLUSIONS: The IOFTN is simple and reliable to use. It is an appropriate aid in the prioritisation of surgical patients. Further recommendations are given.