Effects of incremental mandibular advancement on upper airways morphology and anatomical structures: a preliminary CT scan study on body donors

Obstructive Sleep Apnoea (OSA) is a sleep-related chronic disorder affecting over one billion people worldwide. Mild to moderate OSA can be treated with a Mandibular Advancement Device (MAD), but its effects on airway anatomy remain unclear. The present study aims to standardize upper airway and soft tissue CT measurements and to evaluate three-dimensional changes following progressive mandibular protrusion. Eight body donors underwent CT acquisitions at baseline and at 2 mm mandibular advancement steps up to 12 mm using a MAD-like device. Upper Airway Space (AS), Tongue (T) and Floor of the Oral Cavity (CF) measurements were obtained using a standardized protocol. Inter- and intra-observer reliability were assessed using ICC. Superior Airway Space (SPAS) increased significantly starting from 4 mm, while Inferior Airway Space at Gonion (G-IAS) changed from 6 mm. Inferior portions of T and CF increased from 2 mm, whereas differences in the superior CF occurred only at 12 mm. SPAS and G-IAS appear the most responsive airway regions, while early soft tissue changes are detected in their inferior anatomical sections. High intra- and inter-observer reliability has been observed. Although limited by the model, the proposed protocol provides a reproducible and reliable framework for analysing structural effects of mandibular advancement and may support treatment optimization.