Improved systems, methods, and devices for treating sleep apnea are provided herein. In one aspect, an intraoral appliance for treating sleep apnea in a patient comprises an appliance shell comprising a plurality of cavities shaped to receive teeth of a jaw of the patient. The appliance shell can comprise an advancement structure arranged to interact with an opposing jaw of the patient so as to displace the lower jaw anteriorly relative to the upper jaw. The plurality of cavities can comprise cavity geometries shaped to reduce repositioning of one or more received teeth elicited by displacement of the lower jaw anteriorly relative to the upper jaw.