Changes in mandibular position during midface distraction in patients with syndromic craniosynostosis

The purpose of this study was to evaluate changes in mandibular position during midface distraction. Midface distraction was performed in patients with syndromic craniosynostosis to increase upper airway volume. Although this treatment resulted in changes in occlusion, the concomitant changes in mandibular position were poorly understood. In this retrospective study, three-dimensional (3D) cephalograms were obtained before and after midface distraction in 15 patients with syndromic craniosynostosis. Perioperative polysomnography scores and changes in maxillary and mandibular position, mandibular volume, and upper airway volume were analyzed. Results showed a significant improvement in apnea-hypopnea index (AHI) (from 20.6 +/- 21.3 to 6.9 +/- 5.1, p < 0.05) and upper airway volume (from 2951.65 +/- 2286.38 to 5218.04 +/- 3150.05 mm(3), p < 0.001). When the lowest point of the sella turcica was set as the reference point, the mandible moved significantly in an anterior direction (from 47.9 +/- 11.5 to 51.9 +/- 9.8 mm, p < 0.05). Mandibular volume did not change significantly perioperatively (from 32530.19 +/- 10726.01 to 35590.50 +/- 14879.21 mm(3), p = 0.10). There were positive correlations between the rates of improvement in AHI and the amount of mandibular movement in the anterior and inferior directions (both p < 0.05). Within the limitations of the study, it seems that the mandible moved in the anterior-inferior direction after midface distraction, and the amount of movement correlated with improvement in respiratory function. Therefore, it is important to consider the position of the mandible when determining the direction of midface distraction, as it may influence the therapeutic effect.