The present disclosure provides method, systems, and devices for adjusting an arch of teeth. An appliance includes a removable shell formed of a first material having a number of cavities formed therein, wherein the number of cavities are shaped to receive teeth of a patient, and an arch element extending from the removable shell in a lingual direction and across at least a portion of the arch width of the removable shell, wherein the arch element is designed to expand an arch of the teeth of the patient, wherein the arch element has a width specific to a stage of a treatment plan.