Orthodontic treatment monitoring based on reduced images

The present invention provides digitally driven methods to conveniently and efficiently monitor and evaluate the positions of a patient's teeth during the course of orthodontic treatment. In an exemplary embodiment, an initial set of 3D digital data representing a patient's dental structure is provided by means of an X-ray radiograph and/or an intraoral scan. Then during the course of treatment, a reduced image representing part of the dental structure may be quickly provided using a bite plate or a low resolution intraoral scan. A three-dimensional (3D) image of the full dental structure is subsequently rendered or "reconstructed" by registering elements of the initial image with corresponding elements of the reduced image. By reconstructing the dental structure from the reduced image, the treating professional can provide a precise, manipulable 3D image of the patient's complete dental structure for diagnostic and treatment planning purposes. Other aspects include methods of using these data to compare actual and target teeth positions to evaluate the progress of treatment and suggest revisions to the specification of an orthodontic appliance.