Method and system for detecting and correcting deviation during an orthodontic treatment plan is provided. The method includes the steps of receiving an un-segmented current teeth image representing a patient's teeth after an orthodontic treatment plan has begun and before the plan ends for the patient； matching a previously segmented teeth model with the current teeth image； and generating at least one corrective stage to define an intermediate tooth arrangement, wherein the at least one corrective stage repositions a digital teeth image so that a prescribed tooth arrangement of the previously segmented teeth model can be used.
