Obstructive Sleep Apnoea syndrome and oral appliance therapy : 3D volumetric morphological study before and after orthodontic treatment

Aim: Obstructive Sleep Apnea Syndrome (OSAS) shows apnea or hypopnea due to upper airways stenosis during sleep with its typical symptoms including snoring during sleep and excessive daytime sleepiness. Cone Beam Computed Tomography (CBCT) is useful to reach an accurate 3D volumetric analysis of upper airways. The Oral Appliances (OA) are considered to be an effective treatment for Obstructive Sleep Apnea (OSA). The aim is to detect morphological changes in upper airways using CBCT before and after oral appliance therapy. Methods: The study included 30 patients (18 males and 12 females). They were diagnosed with OSA using polysomnography (PSG). Some criteria have been applied to diagnose OSAS: an apnea-hypopnea index (AHI) of >5 per hour during sleep and pathological daytime sleepiness. The therapeutic effect of oral appliance was evaluated by using PSG and when it showed an AHI of <10 or a decrease of >50%. Two types of OA were applied: the Mandibular Advancement Device and Twin Block Appliance. These enlarged the upper airways by holding the mandible forward, at the 60-70% of the maximum mandible advancement and at the minimum vertical position. A CBCT was performed in all the patients. Results: The mean upper airways’ 3D volumetric reconstructions increased significantly during the presence of OA versus the absence of OA (p<0.01). AHI diminished significantly during the presence of OA (p<0.01). Oral therapy was effective for treating mild and moderate OSA. Conclusion: The advantage of a 3D evaluation of the upper airway during OA therapy is the accurate visual confirmation of morphological changes in each region of the upper airway and it could increase the compliance and motivation of the patients for the treatment. CBCT is useful to detect morphological changes of upper airways, by a 3D evaluation analysis during oral devices’ use. The treatment recommendations should be proposed by a multidisciplinary approach, that involves different specialists.