Reproducibility of the index of orthognathic functional treatment need scores derived from plaster study casts and...

To determine the reproducibility of Index of Orthognathic Functional Treatment Need (IOFTN) scores derived from plaster casts and their three-dimensional (3D) digital equivalents.

Pilot study, prospective analytical.

UK hospital orthodontic department.

Thirty casts and their digital equivalents, representing the pre-treatment malocclusions of patients requiring orthodontic-orthognathic surgical treatment, were scored by four clinicians using IOFTN.

Casts were scanned using a 3Shape digital scanner and 3D models produced using OrthoAnalyzer^TM (3Shape Ltd, Copenhagen, Denmark). Examiners independently determined the IOFTN scores for the casts and digital models, to test their inter- and intra-operator reliability using weighted Kappa scores.

Intra-operator agreement with IOFTN major categories (1-5: treatment need) was very good for plaster casts (0.83-0.98) and good-very good for digital models (0.78-0.83). Inter-operator agreement was moderate-very good for casts (0.58-0.82) and good-very good for digital models (0.65-0.92). Intra-operator agreement with IOFTN sub-categories (1-14: feature of malocclusion) was good-very good for casts (0.70-0.97) and digital models (0.80-0.94). Inter-operator agreement was moderate-good for casts (0.53-0.77); and moderate-very good for the digital models (0.58-0.90).

Digital models are an acceptable alternative to plaster casts for examining the malocclusion of patients requiring combined orthodontic-orthognathic surgical treatment and determining treatment need.