Evidence has recently appeared to indicate that the change in pharyngeal volume caused by protrusion of the mandible, measured while awake, correlates with the change in apnea-hypopnea index (AHI) achieved by OAT, measured while asleep. This is the first convincing evidence that an awake measurement of the pharyngeal airway correlates with the improvement in respiratory status during sleep induced by an oral appliance. The implication is that a simple conebeam CT of the pharynx can predict outcome with OAT. Accordingly, we shall carry out conebeam CTs in the research protocol, both at rest position of the mandible and at 90% of maximal protrusion.