The present invention provides orthodontic appliances and systems, and related methods, for applying a force to a target tooth as an appliances is worn by the patient. One positioning appliance includes a tooth positioning appliance having teeth receiving cavities shaped to apply a positioning force to the patient's teeth. The appliance includes a spring-loaded tooth movement device disposed in the appliance so as to engage an attachment mounted on a surface of a patient's tooth and apply a force to the tooth.