In certain embodiments, an apparatus for treating a breathing condition includes an oral appliance, a mask, and a tensioning device. The oral appliance is configured to receive at least some of a wearer's teeth and a mask. The mask is configured to deliver gas to the wearer. The mask includes a chamber configured to cover the wearer's mouth. The chamber is at least partially enclosed by an interior of the mask. The tensioning device couples the mask to the oral appliance and includes a flexible tension element at least partially disposed between the oral appliance and the mask and within the chamber. The flexible tension element is configured to apply a tensile force between the mask and the oral appliance.
