Post orthodontic decompensation changes in Class III surgical patients. Does the Index of Orthognathic Functional Treatment Needs (IOFTN) reflect these changes?

Abstract

Aims: To 1) assess the changes in the Index of Orthognathic Functional Treatment Needs (IOFTN) score from pre-treatment to pre-surgery and 2) to assess whether a simple Ballard conversion on a pre-treatment lateral cephalogram correlates with the prediction from a pre-surgical lateral cephalogram.

Setting: Orthodontic Department, Edinburgh Dental Institute.

Methods and Materials: A retrospective study conducted using clinical records of 31 patients with Class III malocclusion. Cephalometric tracing was performed using the Dolphin Imaging software and the overjet used to categorize Class III malocclusions according to the IOFTN. A Ballard conversion tracing was carried out manually on tracings from pre-treatment lateral cephalograms. All measurements were performed by one examiner and were repeated to assess the intra-examiner reliability. For statistical analysis, Intraclass Correlation Coefficients (ICCs), method error, and paired t-tests were used to evaluate the reliability and reproducibility, together with Bland-Altman graphs for all variables. Descriptive statistics and paired t-tests were used to analyse pre-treatment (T0), pre-surgery records (T1) and post-Ballard conversion tracings.

Results: The pre-treatment distribution of cases according to IOFTN was as follow: grade 5 = 45.2 %, grade 3&4 = 41.9 % and grade 1 = 13.9 %. Cases with grade 5 category increased up to 77.4% and 96.8% after decompensation and Ballard conversion respectively. After decompensation, the IOFTN category changed in 48.4% of the cases and in 96.8% post-Ballard conversion.

Conclusion: The IOFTN grades increased after orthodontic decompensation. Also, increased after Ballard conversion with almost all cases (30 out of 31) allocated to IOFTN grade 5. Ballard conversion could be used as an adjunctive tool when assessing orthognathic patients using the IOFTN.

Key words: Orthognathic, IOFTN, Class III, IOTN.