Oral appliance therapy (OAT) is a treatment for obstructive sleep apnea and an effective alternative treatment to CPAP. Administered by a dentist, oral appliance therapy uses a custom-fit “mouth guard-like” device worn only during sleep to maintain an open, unobstructed airway. The following short video provides a brief overview of the fitting process for oral appliances. Read more about oral appliance therapy in the Oral Appliances section of the Dental Sleep Medicine Dictionary.