Oral appliances, methods of making oral appliances, and bite registration devices for use in making oral appliances are provided. An oral appliance includes a lower segment, and upper segments. The upper segments are operably connected to the lower segment using threaded elements. Rotational manipulation of the threaded elements causes the upper segments to be displaced horizontally relative to the lower segment about the lengths of the threaded elements, and the lengths of the threaded elements are substantially parallel to each other. A bite registration device for use in making an oral appliance includes a top surface including a protrusion and a bottom surface including a receptacle configured to receive the protrusion. The device is configured to be maintained in stacked relation to a like configured second bite registration device by mating the protrusion of the bite registration device with a receptacle of the second bite registration device.