An intra-oral dental appliance for treatment of sleep disorders including snoring, sleep apnea and nocturnal bruxism. The appliance includes an upper member conforming to the patient's maxillary dentition; a lower member conforming to the patient's mandibular dentition; and a connecting assembly for adjustably coupling the upper and lower members together. The connecting assembly includes a first element mounted on the upper member, the first element having a cavity therein; a second element mounted on the lower member; and a connector having a first end captured within the cavity and a second end adjustably connectable to the second element. The connecting assembly maintains the lower member in a protruded position relative to the upper member to maintain the patency of the user's pharnygeal airway while permitting anterior and lateral movement of the lower member relative to the upper member in the protruded position.