Fuente: Wipo "digitalization" Methods and apparatus for building physical and/or digital dental models are described herein. Methods and apparatus that can be utilized within the process of building a physical and/or digital dental model are also disclosed herein. In one implementation, individual physical tooth models are created and then arranged into a tooth arch to serve as the underlying template for fabricating a dental aligner. A registration feature may be implemented on each of the physical tooth models to track the positions of the individual physical tooth models relative to the other tooth models in the tooth arch. In one application, information regarding the registration features is mapped from the digital space into the physical space and vice versa. By tracking changes in the registration features, one can arrange individual physical tooth models to form a physical tooth arch that reflects the arrangement of the teeth in a digital tooth model.