 Acephalometric analysis was conducted on 100 patients with obstructive sleep apnea or habitual snoring who underwent mandibular advancement splint treatment for up to 30 months. Significant changes in the oropharynx and velopharynx were observed, including an increase in the posterior airway space from 10.71 mm to 11.99 mm at 12 months, mean difference, 1.28 mm. The soft palate length and thickness decreased by a mean of 1.46 mm and 0.57 mm, respectively, at 6 months, P less than 0.0001, while no changes were observed in the hypoferynx or hyoid bone position. This article was authored by Robertson Christopher J.