Wee JH, et al. - In this observational cohort study, the researchers identified adequate criteria to determine the success or failure of mandibular advancement device (MAD) treatment for obstructive sleep apnoea (OSA) based on long-term symptoms and new-onset hypertension. They enrolled patients (age >18 years) who were diagnosed with OSA by a polysomnography (PSG) or Watch peripheral arterial tonometry (PAT), and who had been treated with MAD between January 2007 and December 2014. The long-term follow-up survey for symptoms and new-onset hypertension suggested that some of the polysomnographic success criteria, that is, apnoea-hypopnoea index (AHI)<10/hour with MAD, AHI<10/hour and AHI reduction of >50% with MAD and AHI<15/hour with MAD could be helpful in distinguishing the success group from failure one.