IntroductionMandibular advancement device (MAD) may represent a feasible choice in the treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS), in well selected patients.ObjectiveThe aim of this study is to assess the efficacy of MAD in patients with OSAHS, using split night polysomnography (SNP)MethodWe performed an auto controlled clinical trial to assess the efficacy of MAD in 30 patients with snoring and OSAHS. Clinical evaluation was made every 2 weeks to adjust treatment and observe changes in clinical symptoms. Three-months after placement of the MAD, a SNP was performed, using the MAD in the second half of the night, in order to compare the respiratory results.ResultsSNP show significant changes with use of MAD (p<0.05) such as: Decrease in Snore index (from 159.95 to 32.46/h) and in Apnea-hypopnea index (AHI, from 22.45 to 4.63/h), increase in oxygen saturation (SaO2, from 89.98% to 91.39%) and somnolence improvement, using the Epworth Sleepiness Scale (from 14.4 to 4.6 points).ConclusionOur data supports that the use of MAD is an alternative in the management of OSAHS, in well selected patients, used in a multidisciplinary fashion, and evaluated using a SNP.