Effect of Sagittal Maxillary Rotation on Inferior Scleral Exposure in Class III Maxillary Deficiency.

Area of Science:

• Orthognathic Surgery
• Maxillofacial Surgery
• Plastic Surgery
• Oculoplastics

Background:

• Inferior scleral exposure (ISE) significantly impacts facial aesthetics and harmony.
• While linear maxillary movements are studied, the influence of sagittal-plane rotational vectors on ISE is less understood.

Purpose of the Study:

• To quantify the association between sagittal-plane maxillary rotational changes and ISE following LeFort I osteotomy.

Main Methods:

• Retrospective cohort study of 42 patients undergoing LeFort I osteotomy for Class III maxillary deficiency.
• Sagittal occlusal plane rotation (clockwise [CW] and counterclockwise [CCW]) was the primary predictor.
• ISE changes were assessed pre- and postoperatively using vertical pupil-lower eyelid distance and visible scleral area measurements.

Main Results:

• CW rotation was associated with a statistically significant decrease in ISE (P = .005-.041).
• No significant ISE change was observed with CCW rotation.
• Sagittal rotation magnitude did not correlate with ISE changes (r = -0.12 to -0.15; P = .5-.9).
• Vertical maxillary repositioning remained a significant predictor of scleral reduction (P = .02), while sagittal rotation was not an independent predictor.

Conclusions:

• Univariate analysis showed CW maxillary rotation correlated with reduced ISE.
• Vertical repositioning emerged as the significant independent predictor of ISE changes.
• Comprehensive consideration of multiple vector components is crucial for virtual orthognathic surgical planning.