A sleep apnea oral appliance is typically molded to fit a particular patient's teeth by a dentist specializing in treating sleep disorders. Appliances usually function by moving the lower jaw forward in order to open up the airway during sleep, thus promoting better breathing and less apneas. Some oral appliances restrict tongue movement in order to prevent the tongue from blocking the airway.
Oral appliances have a mixed success rate in treating sleep apnea. They are generally more successful at treating mild and moderate sleep apnea and less effective at treating severe sleep apnea. They may bring the level of apnea a patient experiences down significantly but fail to completely eliminate it. Their popularity stems largely from the fact that most patients find them more comfortable than CPAP machines (the most common sleep apnea treatment). Because they are perceived as comfortable, patients are more likely to wear them consistently and comply with treatment.
A device used to reposition the lower jaw is known as the MORA (Mandibular Orthopedic Repositioning Appliance) or Gelb Appliance. It uses clear acrylic bite pads that cover the molars and bicuspids.