Technique for defining a position of a model of an anatomy of a patient's dental arch within a global reference frame

A computer-implemented method for defining a position of an origin and axes of a model of an anatomy of at least a part of a patient's dental arch within a global spatial reference frame, comprising the steps of:

• receiving a first dataset comprising a surface representation representing a surface topology of at least a part of the patient's dental arch and at least the crowns of one or multiple teeth, the first dataset comprising:
• a plurality of segmentation lines, each representing a border between a tooth crown and adjacent soft tissue, and
• an indication of a first rotation angle for orienting the surface representation such that a main orientation vector representing a normal vector of an occlusion plane is aligned with a first main component of the global spatial reference frame, and, optionally, an indication of a second rotation angle for orienting the surface representation such that an anterior-posterior vector direction of the patient's dental arch is aligned with a second main component of the global spatial reference frame;
• optionally, generating a planar projection of each segmentation line into a plane parallel to the occlusion plane;
• determining, for each planar projected segmentation line, a projected location of a center of a tooth in the plane parallel to the occlusion plane, for example, as the centroid of an area bounded by the planar projection of the segmentation line;
• fitting a segment of a parabola to the determined projected locations of the centroids of the segmentation lines;
• defining an anterior point of the patient's dental arch to coincide with the vertex of the parabola;
• determining a first translation vector for positioning the anterior point at the origin of a third main component of the global spatial reference frame;
• and
• storing an indication of the first translation vector in association with the surface representation.