The present invention provides methods and systems including orthodontic tooth positioning appliances. An exemplary appliance can include teeth receiving cavities shaped such that, when worn by a patient, repositioning the patient's teeth from a first arrangement toward a subsequent or target arrangement. Appliances can include a cavity having one or more shaped features or protrusions shaped and/or positioned so as to apply a desired force to a patient's tooth received in the cavity and move the tooth along a desired path or direction.
From the international application WO2009097054