Obstructive sleep apnea (OSA) is a highly prevalent breathing problem that occurs during sleep. OSA have been associated with the obesity epidemic in developing countries; additionally, high OSA prevalence rates are present in populations with cardiovascular and metabolic disorders. Two OSA treatments are currently available, oral appliance (OA) therapy and continuous positive airway pressure (CPAP). OAs are an underutilized non-surgical treatment and few studies have analyzed their long-term effectiveness for patients with OSA. The purpose of this study is to assess the long-term effectiveness of OA therapy in patients with OSA and to explore any changes on cardiovascular related morbidity and mortality related to this therapy.