Patients are classified as mild Obstructive Sleep Apnea (OSA) if they have between 5-15 Apnea-Hypopnea Index, moderate if they have between 15-30, and severe if they have >30, as measured by Polysomnography (Epstein LJ, Kristo D, Strollo PJ, et al. 2009). The principal treatment methodology for OSA patients is positive airway pressure. In patients with mild to moderate OSA, oral appliances such as mandibular advancement devices (MAD) is alternately indicated (Ramar K, Dort LC, Katz SG, et al. 2015) The American Academy of Dental Sleep Medicine (Ramar K, Dort LC, Katz SG, et al. 2015) recommended titratable-customized MADs for patient comfort and the ability to permit modifications in the amount of mandibular protrusion for treatment efficacy. However, Aarab et al (Aarab G, Lobbezoo F, Hamburger HL, Naeije M. 2010) demonstrated similar therapeutic efficiency of non-titratable-customized MADs in the treatment of OSA

The most comfortable protruded mandibular position situated between 60-75% of MMPV was determined according to patient response with 6mm of the vertical interocclusal dimension between maxillary and mandibular central incisors and registered. The upper and lower acrylic resin splints were secured to each other in the posterior region with auto polymerizing acrylic resin and NTC-MADs were obtained. The patients were instructed to wear their non-titratable-customized mandibular advancement device every night.

AHI was defined as total number of apnea or hypopnea events which lasts for at least ten seconds per hour during full nigth polysomnography (PSG) and accepted to be the main physiological sleep parameter in the present study. The AHI values were used for the evaluation of the severity of OSA and the MAD's treatment success in OSA patients

ODI was used to evaluate the desaturation fluctuations during full night PSG. ODI is defined as 3-4% decrease in oxygen saturation per hour.