Surgical Accuracy in Inferior Maxillary Reposition

Purpose: Inferior maxillary repositioning is among the least stable and least predictable orthognathic procedures. The purpose of this study was to investigate whether posterior movement occurred with inferior maxillary repositioning and to analyze potential causes. Materials and Methods: This retrospective observational study evaluated all consecutive patients treated at the Department of Oral and Maxillofacial Surgery of the Odense University Hospital (Odense, Denmark) with inferior maxillary repositioning from 2011 to 2013. The obtained repositioning was compared with the virtual surgical plan to determine surgical accuracy. Measurements were performed at 3 dental reference points. Linear and rotational measurements were performed along and around the right, anterior, and superior axes. Measurements were compared by paired t tests. Internal correlations and confounding variables were analyzed by mixed model regression analysis. Results: Twenty patients were included for analysis. On average, the maxilla was positioned 1 mm posterior and 0.4 mm superior to the planned position. The virtual surgically planned reposition was statistically correlated with surgical accuracy. No other confounding variable influenced the outcome. Conclusion: The correlation between planned advancement and inferior repositioning suggests that inferior repositioning destabilizes the maxillary position and that a perioperative or early postoperative relapse occurs in response to the advancement. This immediate relapse of 1 mm should be considered in the virtual surgical plan to ensure that the maxilla is placed closer to the desired position. Thus, this procedure could still benefit from increased surgical precision and stability based on technologic advancements, such as positioning guides or printed patient-specific plates. (C) 2018 American Association of Oral and Maxillofacial Surgeons