Sleep apnea is a common disorder that occurs in 3-10 % of the adult population. This disorder disrupts the architecture and quality of sleep. Continuous positive airway pressure (CPAP) therapy is the standard treatment, but in some cases, it can not be used (patient refusal or intolerance). In these cases, treatment with mandibular advancement devices can bring an improvement in symptoms. Therefore, this study aims to compare the effectiveness of titratable versus active mandibular advancement splints in standard care environment. This will be based on the global response, which includes the apnea-hypopnea index and compliance in severe apnea patients who refused or where intolerant to CPAP. Following their severe apnea diagnosis and the assessment on the feasibility of placing a mandibular advancement device, follow-up visits will be scheduled after 3 months of treatment involving clinical monitoring by a physician and a dentist.

Inclusion Criteria:

• age between 18 and 65 years
• severe OSA confirmed by polysomnography (PSG) is: 30> AHI> 15 with severe daytime sleepiness - Epworth ≥ 10 or AHI> 30
• patient in failure or refusal of CPAP treatment
• agree to participate and sign the consent form research
• speak and understand French without external assistance
• be in good health (no neurological or psychiatric syndrome).
• have a valid Social Security card (in France and Portugal only)

Exclusion Criteria:

• contra-indicated dental/periodontal states for mandibular advancement splints, such as: 1) significant edentulism (less than 3 healthy teeth / quadrant), 2) generalized periodontitis or severe parodonthopathies, 3) severe disorders of the temporomandibular joint (TMJ), 4) less than 5 mm of maximal mandibular protrusion
• dental restorations in progress or planned in the next 6 months
• psychiatric and neuromuscular disorders
• untreated cardiovascular diseases and history of stroke or myocardial infarction
• severe or morbid obesity (body mass index> 35)