Abstract: A universal, user-adjustable oral cavity appliance is provided for maintaining the mandible in an open and forward position during sleep. The appliance includes a lingual mandibular retaining strap adapted to contact and imbed in the lingual mandibular tissues below the mandibular anterior teeth and a labial maxillary retaining strap adapted to contact and imbed in the labial maxillary tissues above the maxillary anterior teeth. The retaining straps are adjustably connected such that the relative position of each strap to the other may be varied to obtain a separation between the maxilla and mandible and a forward thrust of the mandible sufficient to prevent the occlusion of the oropharyngeal airway.