Implication for practiceBased on the results of this review, it seems that the prolonged use of MAD (more than oneyear) is as effective as CPAP in reducing the AHI. Quality of evidence, however, is verylow, which might weaken the recommendations.Implications for researchWe need further properly conducted and designed RCTs with follow up periods longerthan one year, reporting snoring index, apnea hypopnea index, excessive daytime sleepinessand health quality of life score outcomes. These trials should have calculated sample sizesand a wash out period of at least two weeks between the treatments. The methodology shouldhave adequate random sequence generation, allocation concealment, with propermanagement of incomplete data and reported as recommended by the CONSORT statement(www.consort.org).