Fig. 1

Superimposition and markers. The first and second molars, highlighted in red, served as the regions of interest for superimposition. Markers were placed from premolar to contralateral premolar cusp tips, centers of incisal edges, and at the intersections of the facial axis and gingival margin of each tooth. A and B Maxillary superimposition; C and D Vertical movement and inclination changes. C The difference in the vertical position of I-9 and F-9 represents the vertical movement of the tooth; D The difference in angulation from lines I-9 to I-16 and F-9 to F-16 represents the inclination change of the tooth