Ramal inclination in the frontal plane after bimaxillary orthognathic surgery in skeletal class III facial asymmetry : Spontaneous changes and stability.

Purpose: This study aimed to observe spontaneous changes of ramal inclination in the frontal plane (FRI) and its stability in skeletal class III asymmetry patients corrected with bimaxillary surgery. The correlation between FRI change and surgical skeletal change was also investigated.

Methods: Forty-nine patients with skeletal class III facial asymmetry who underwent orthognathic surgery with at least 1° change in FRI after surgery were analyzed. FRI and other factors were measured on frontal and lateral cephalograms before surgery (T1), after surgery (T2), and at follow-up after at least 6 months (T3). Correlation analysis was performed to determine pre- and postoperative factors associated with FRI change and stability.

Results: FRI increased significantly on the deviated side and decreased on the nondeviated side after surgery. The FRI changes remained stable during follow-up. No correlation between FRI changes and skeletal changes during surgery were found except between the change of FRI during follow-up (T3-T2) and mandibular setback amount (T2-T1), with a weak coefficient of 0.32.

Conclusion: The FRI changes after bimaxillary orthognathic surgery in skeletal class III asymmetry reduced the FRI difference between the deviated and nondeviated side and remained stable for at least 6 months after surgery. No clinically significant correlation was found between measured skeletal changes during surgery and FRI changes.