Long-term three-dimensional effects of orthognathic surgery on the pharyngeal airways: a prospective study in 128 healthy patients.

Abstract

To investigate volumetric and circumferential pharyngeal airway space (PAS) changes and stability over time as evaluated with cone beam computed tomography (CBCT) before and after orthognathic surgery 2years postoperatively. One hundred twenty-eight patients underwent bimaxillary orthognathic surgery at the Department of Maxillofacial Surgery of University Hospitals, Leuven, Belgium, were recruited prospectively. Patients were divided into 4 groups based on the amount of mandibular advancement in 5mm increments (< 0mm, 0-5mm, 5-10mm, or > 10mm). CBCT data was acquired preoperatively and 1-6weeks, 6months, 1year, and 2years postoperatively. Patients with a history of maxillofacial trauma or surgery, obstructive sleep apnoea syndrome, or craniofacial anomalies were excluded. Nasopharyngeal, oropharyngeal, and hypopharyngeal PAS volumes and constriction surface areas (mCSA) were measured and compared between each time point with a paired t-test. The largest significant increase in oropharyngeal volume and mCSA were observed in the 5-10mm (+ 13.3-21.7%, + 51.3-83.0%)) and > 10mm (+ 23.3-44.6%, + 92.3-130.0%) mandibular advancement groups. This increase only remained stable 2years postoperatively in the > 10mm group. In other mandibular advancement groups, short-term oropharyngeal volume and mCSA increases were noticed, which returned to baseline levels 6months to 1year postoperatively. Bimaxillary advancement osteotomy significantly increases oropharyngeal volume and mCSA, which remains stable between 6months to 1year postoperatively. Long-term stable volumetric and mCSA enlargements were found with > 10mm mandibular advancements over a period of 2years. Return towards baseline levels was observed in the other mandibular advancement groups.