Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40510-016-0119-z/MediaObjects/40510_2016_119_Fig1_HTML.gif)
a Reference points and planes: mandibular plane (MP); Ax36, Ax37, Ax46, and Ax47: first and second molar long axes constructed by the midpoints of the occlusal surfaces and root apexes of the molars; mesiodistal dimension of second molar crown (MD); centroid of the mandibular second molar (37C); molar inclination angles: 36-MP, 37-MP, 46-MP, and 47-MP. b Best fit superimposition of panoramic radiographs taken at T1, T2; in squares: centroids of mandibular second molar at T1, T2 (37CT1, 37CT2); movement of centroids along the molar long axis (V); white circles: digitization points at T1; grey circles: digitization points at T2