CBCT scans
Two CBCT scans (NewTom 5G, QR systems, Italy) were performed for every participant at the department of Oral Radiology of the Academic Centre for Dentistry Amsterdam (ACTA): one without MAD at baseline and one with MAD in situ at 3-month follow-up in the same protrusion position as during the follow-up PSG recording. CBCT scans were performed while the patient was awake in the supine position with quiet breathing. The head of the patient was positioned with the Frankfort plane being perpendicular to the floor. After CBCT scanning, we further standardized the head position, during which the palatal plane (anterior nasal spine (ANS)-posterior nasal spine (PNS)) was adjusted to be parallel to the axial plane and the sagittal plane, and perpendicular to the coronal plane [