A computing device implemented method for evaluating a course of a treatment for a patient prior to completion of the treatment or after completion of the treatment, the method comprising: correlating a first 3D virtual model associated with the patient's dentition at a first time and a second 3D virtual model associated with the patient's dentition at a second time to spatially interrelate the first 3D virtual model and the second 3D virtual model, the second time being later in time than the first time; displaying the first 3D virtual model superimposed with the second 3D virtual model according to the correlation of the first 3D virtual model with the second 3D virtual model; generating a 2D image including a first 2D virtual outline representing a position of at least one tooth of the patient's dentition according to the first 3D virtual model and a second 2D virtual outline representing a position of the at least one tooth according to the second 3D virtual model , wherein generating the 2D image includes positioning the first 2D virtual outline relative to the second 2D virtual outline according to the correlation of the first 3D virtual model and the second 3D virtual model, and wherein the first 2D virtual outline and the second 2D virtual outline are generated according to a plane of a virtual camera in the first 3D virtual model and the second 3D virtual model, the plane being associated with user input; wherein the first 2D virtual outline of the at least one tooth is generated as they appear in the plane of the virtual camera, and wherein the second 2D virtual outline of the at least one tooth is generated as they appear in the plane of the virtual camera. correlating a first 3D virtual model associated with the patient's dentition at a first time and a second 3D virtual model associated with the patient's dentition at a second time to spatially interrelate the first 3D virtual model and the second 3D virtual model, the second time being later in time than the first time; displaying the first 3D virtual model superimposed with the second 3D virtual model according to the correlation of the first 3D virtual model with the second 3D virtual model; generating a 2D image including a first 2D virtual outline representing a position of at least one tooth of the patient's dentition according to the first 3D virtual model and a second 2D virtual outline representing a position of the at least one tooth according to the second 3D virtual model , wherein generating the 2D image includes positioning the first 2D virtual outline relative to the second 2D virtual outline according to the correlation of the first 3D virtual model and the second 3D virtual model, and wherein the first 2D virtual outline and the second 2D virtual outline are generated according to a plane of a virtual camera in the first 3D virtual model and the second 3D virtual model, the plane being associated with user input; wherein the first 2D virtual outline of the at least one tooth is generated as they appear in the plane of the virtual camera, and wherein the second 2D virtual outline of the at least one tooth is generated as they appear in the plane of the virtual camera. <EOS>