Predictability of the orthodontic-surgical planning: a comparative study between the post-operative outcome and the visual treatment objective

Objective:To test the validity of lateral pre-treatment and pre-surgical VTO, by comparing them with the post-treatment lateral cephalometry. Methods: A total of 26 patients affected by Class III who underwent orthognathic surgery were evaluated. For all patients, pre-treatment (T0), pre-surgical (T1) and post-treatment (T2) cephalometric tracings, pretreatment and pre-surgical VTO were performed. Nine measurements of hard tissues were considered. A comparison was made between pre-treatment and pre-surgical cephalometric measurements, post-treatment cephalometric tracing and pre-treatment VTO, post-treatment cephalometric tracing, and pre-surgical VTO. Descriptive and inferential statistics along with Bland-Altman plot were used to analyze the agreement between the outcome and the program. Results: From the comparison between pre-treatment and pre-surgical values, a statistically significant difference was found for the SNB angle (P=.0292), the inclination of the upper (P=.0309) and lower incisors (P<.000) and the over-jet (P<.000). The comparison between the post-treatment cephalometry (T2) and pre-treatment VTO (T0) highlighted good agreement between overbite and over-jet values. The comparison between the post-treatment cephalometry (T2) and pre-treatment VTO (T0) highlighted good agreement with over-jet and IMPA angle. All parameters had high dispersion and the Bland-Altman plot appeared to be scattered. Conclusion: Given the bias and the imprecisions between the orthodontic-surgical program and the outcome, the indications given by 2-dimensional VTO should be used with caution.