Measuring the accuracy in occlusion after orthognathic surgery: -Presenting a new method applied to 145 bimaxillary procedures

Kasper Stokbro, Jeroen Liebregts, Frank Baan, Bryan Bell, Thomas Maal, Torben Thygesen, Tong Xi

Research output: Contribution to conference without publisher/journalConference abstract for conferenceCommunication

Abstract

Objectives
Treating malocclusion is one of the most important goals in orthognathic surgery. However, the occlusion is not included in conventional postoperative outcome analysis. This study presents a new method for measuring the difference between the planned and the obtained postoperative occlusion. The purpose of this study was to evaluate the impact of surgical sequencing on the postoperative occlusion in patients who had undergone bimaxillary procedures and evaluate surgical and patient-related covariates.

Materals and Methods
The method for measuring the accuracy of the post-surgical occlusion was implemented in a retrospective cohort. All patients were treated from 2010 to 2015. The inclusion criterion was bimaxillary surgery without maxillary segmentation. The exclusion criterion was the lack of a virtual surgical plan. The primary outcome variable was the occlusal shift, defined as the difference between the surgical accuracy of the mandible and the surgical accuracy of the maxilla. The primary predictor variable was the difference between mandible-first and maxilla-first procedures. Secondary predictors were inferior maxillary repositioning, counterclockwise rotation, and gender. Results were analyzed by mixed-model regression analysis and 2-sample t-tests.

Results
The study included 145 patients (69% females, mean age 28 years). The mandible-first procedures were placed closer to the planned occlusion than the maxilla-first procedures, but the difference was less than 0.5 mm. Superior maxillary repositioning affected the occlusion more than inferior repositioning. The occlusion in clockwise rotation showed a tendency toward anterior open bite in maxilla-first procedures. Gender presented a surprisingly large influence on occlusion. Male patients showed less than 0.6 mm vertical difference, but female patients showed an anterior open bite of 1.4–1.6 mm.

Conclusion
The mandible-first procedures placed the occlusion closer to the planned position than the maxilla-first procedures. However, this difference was below clinical relevance. Other covariates, such as gender, had a greater influence on postoperative occlusion than surgical sequencing.
Original languageDanish
Publication date30. Sept 2022
Publication statusPublished - 30. Sept 2022
EventCongress of the European Association for Cranio Maxillo Facial Surgery - Palacio Municipal de Congresos de Madrid, Madrid, Spain
Duration: 27. Sept 202230. Sept 2022
Conference number: 26
https://www.emma.events/eacmfs2022/welcome

Conference

ConferenceCongress of the European Association for Cranio Maxillo Facial Surgery
Number26
LocationPalacio Municipal de Congresos de Madrid
Country/TerritorySpain
CityMadrid
Period27/09/202230/09/2022
Internet address

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