An exemplary receiver demodulates an amplitude modulated data signal received in association with a reference signal, wherein a transmit power of the data signal is unknown to the receiver circuit, by determining a scaling factor based on the reference and data signals. The appliances are configured to be placed successively on the patient’s teeth and to incrementally reposition the teeth from an initial tooth arrangement, through a plurality of intermediate tooth arrangements, and to a final tooth arrangement. In a subdivision process, faces might be represented by polygons through a method of repeated subdividing.