A method of correcting a dental arch model so that it accurately reflects the current arrangement of a subject's teeth includes positioning a plurality of tooth models in a corrected arrangement using a representation of at least a portion of a subject's current dental arch (wherein the tooth models comprise models of the subject's teeth having fiduciary markers), and producing a base plate configured to hold the plurality of tooth models in the corrected arrangement. The representation of the current arrangement may be, for example, a physical impression of the subject's teeth, a 3D scan or one or more 2D scans of the subject's teeth.