Inclusion Criteria:  Age: >18 and <80 years old. No history of previous use of a MAD. Diagnosis of OSA by a sleep physician based on a PSG or HSAT (done >12 months before evaluation date or > 12 months with >10% variation of BMI). Upon clinical examination: >8 teeth per arch; range of anteroposterior mandibular mobility >5 mm. Informed consent to participate in the study.  Exclusion Criteria:  Patients with concomitant diagnosed sleep disorders (i.e. insomnia, narcolepsy, restless legs syndrome, rapid eye movement sleep behavior disorder). History of previous allergic reaction to the appliance material (Polyamide 12). Patients using combination therapy for the management of OSA (i.e. PAP therapy or positional therapy). Upon clinical examination: periodontal disease (>4 mm on periodontal probing, with bleeding on probing, visual signs of periodontal inflammation); tooth horizontal mobility >1 mm, vertical mobility, and unfavorable crown to root ratio; open cavities, loose or fractured restorations, or patient undergoing restorative dental treatments. Exaggerated gag reflex. Lack of coordination or dexterity. Inadequate English comprehension.