A system and method for evaluating dental treatment utilizes virtual models created from scanned plaster casts. Patient's teeth are directly scanned with a three dimensional scanner or plaster casts of the patient teeth following treatment are scanned for evaluation. A planned configuration based on a plaster cast prior to treatment is created and the desired position and the two models are compared so that the actual position of the teeth may be compared to the desired position after treatment. Superimposition of the virtual models provides accurate and precise measurement of variances between the two virtual models. Difficulties due to superimposing the models, which are of the entire arch and evaluations based on individual teeth are overcome by applying an iterative closest point algorithm to correct the position and provide a truer measurement for evaluation. Differences between a preferred position of a patient's teeth and actual position of a patient's teeth may be assigned a score and the score may be compared to other patients to rank the patient needs.