How Much Inter-Arch Discrepancy Occurs During Orthognathic Surgery?

Area of Science:

• Oral and Maxillofacial Surgery
• Orthodontics
• Biomedical Engineering

Background:

• Accurate virtual surgical planning transfer is crucial for orthognathic surgery.
• Intraoperative adaptation errors, particularly interarch discrepancy, are not well-documented.
• Surgical splints are vital for guiding the transfer of planning to the operative field.

Purpose of the Study:

• To define and quantify interarch discrepancy during splint-guided orthognathic surgery.
• To evaluate if facial symmetry influences the magnitude of interarch discrepancy.
• To assess the impact of surgical sequence on interarch discrepancy.

Main Methods:

• Retrospective cohort study of 119 patients with skeletal Class III malocclusion.
• Analysis of interarch discrepancy using 3D vector components and root mean square (RMS) magnitude.
• Statistical comparison based on facial symmetry and surgical sequence (maxilla-first, mandible-first, mandible-only).

Main Results:

• A statistically significant inferior deviation was observed across all regions (anterior, posterior).
• The overall root mean square (RMS) discrepancy was 1.23 ± 0.61 mm, indicating a modest magnitude.
• Facial symmetry and surgical sequence were not significantly associated with the overall RMS discrepancy.

Conclusions:

• Interarch discrepancy in splint-guided orthognathic surgery demonstrates a consistent inferior displacement.
• The overall magnitude of this discrepancy is modest and not significantly influenced by facial symmetry or surgical sequence.
• Findings contribute to understanding intraoperative adaptation errors in orthognathic surgery.