A method of orthodontic treatment planning for a patient includes receiving three-dimensional intraoral surface scan data of a dentition of the patient, receiving three-dimensional volumetric scan data of the dentition of the patient, and overlaying the intraoral surface scan data and the volumetric scan data to generate an integrated patient model comprising a root of at least one tooth having a longitudinal axis. The method further includes determining, for use in planning an orthodontic treatment, a center of rotation of the at least one tooth, wherein the center of rotation is defined as a point located a predetermined distance from a base of the root to an apex of the root along the longitudinal axis of the at least one tooth in the integrated patient model.