Shell-shaped tooth repositioner and fabrication method thereof

A method of fabricating a shell-shaped repositioner for repositioning teeth from a first tooth arrangement to a second tooth arrangement, comprising:

• obtaining a first 3D digital model representing the first tooth arrangement, a second 3D digital model representing the second tooth arrangement and information of restrictions on anchorage force bearing of a first tooth among the teeth;
• modifying the second 3D digital model based on the first 3D digital model and the information of restrictions on anchorage force bearing of the first tooth, to obtain a third 3D digital model, wherein the second 3D digital model is modified by modifying three dimensional geometry of 3D digital model of the first tooth;
• and
• controlling an apparatus using the third 3D digital model to fabricate the shell-shaped repositioner,
• wherein said modifying the second 3D digital model based on the first 3D digital model and the information of restrictions on anchorage force bearing of the first tooth, to obtain a third 3D digital model comprises:
• calculating an anchorage force applied to the first tooth by a shell-shaped repositioner to be fabricated using the second 3D digital model;
• determining whether the calculated anchorage force complies with the restrictions on anchorage force bearing;
• and
• if the calculated anchorage force complies with the restrictions on anchorage force bearing, determining the second 3D digital model as the third 3D digital model, and if the calculated anchorage force does not comply with the restrictions on anchorage force bearing, modifying and updating the second 3D digital model based on the restrictions on anchorage force bearing and the calculated anchorage force.