Oral appliances for sleep apnea, also known as mandibular advancement devices or MADs, are a popular alternative to CPAP for the treatment of obstructive sleep apnea (OSA). In order to be a candidate for a MAD, you must first have a sleep study that shows OSA in the mild to moderate range (5-30 abnormal breathing events per hour). Severe sleep apnea (>30 abnormal breathing events per hour) and more complex sleep breathing disorders such as central sleep apnea and hypoxemia preclude you from being a good candidate for an oral appliance.