Sleep apnea appliances, also known as oral appliances or mandibular advancement devices (MADs), are dental devices used for treating obstructive sleep apnea (OSA) and snoring. They are worn only during sleep and fit like a sports mouthguard or an orthodontic retainer. The device supports the jaw in a forward position to help maintain an open upper airway, and research has shown it to be an effective treatment option for sleep apnea.