Does Mandible-First Sequencing Increase Maxillary Surgical Accuracy in Bimaxillary Procedures?

Area of Science:

• Oral and Maxillofacial Surgery
• Orthognathic Surgery
• Surgical Planning

Background:

• Bimaxillary procedures involve simultaneous or sequential repositioning of both jaws.
• The order of surgical intervention (mandible-first vs. maxilla-first) may influence the final outcome.
• Understanding sequencing effects is crucial for optimizing surgical results.

Purpose of the Study:

• To evaluate whether the theoretical benefits of a mandible-first approach in bimaxillary surgery are supported by clinical data.
• To compare the surgical accuracy between mandible-first and maxilla-first sequencing.

Main Methods:

• Retrospective analysis of 145 patients undergoing bimaxillary surgery without maxillary segmentation.
• Data compiled from three previous retrospective studies (2010-2015).
• Primary outcome: surgical accuracy (difference between planned and actual outcome); Primary predictor: surgical sequence (mandible-first vs. maxilla-first).

Main Results:

• Mandible-first sequencing resulted in a mean posterior maxillary repositioning of 1.5 mm and 1.4° counterclockwise rotation compared to virtual surgical plans.
• Surgical accuracy was comparable between maxilla-first with clockwise rotation and mandible-first with counterclockwise rotation.
• Inferior maxillary repositioning led to posterior displacement in both sequences (1.7 mm for maxilla-first, 2.0 mm for mandible-first).

Conclusions:

• Surgical sequencing significantly influences outcomes in bimaxillary procedures.
• Awareness of sequencing effects allows for informed adjustments to virtual surgical plans.
• Optimizing surgical sequence is key to achieving desired patient outcomes.