The present invention relates to systems and methods of developing and tracking delivery and patient progression through an orthodontic treatment plan. One method includes identifying deviations from an orthodontic treatment plan, including receiving a digital representation of an actual arrangement of a patient's teeth after an orthodontic treatment plan has begun for the patient and prior to completion of the orthodontic treatment plan. The method further includes comparing the actual arrangement to a pre-determined planned arrangement to determine if the actual arrangement substantially deviates from the planned arrangement, the comparing comprising matching teeth from a previously segmented model to a surface of an unsegmented representation of the actual arrangement； and calculating one or more positional differences between the actual and planned arrangements of at least some of the corresponding teeth.
