Fig. 2

Management of compared digital models

A, Digital model acquisition: All casts were scanned using a scanner (TRIOS POD 2, 3 Shape Inc.) performed by an experienced operator. All digital models were assessed using reverse engineering software (Geomagic 2013, 3D Systems Inc.). B, Digital model matching: “N-point alignment” of two digital models used the selected “characteristic points” as a reference. After aligning the two models to the same coordinate system, the best fitting alignment was carried out, and the number of sampling points was 5000.RMS and color-coded map were calculated to check the alignment. In the spectrum, the color was closer to the center of green, the RMS was less, Distance calculation: After the best fitting alignment, the elongated tip of the target teeth on the digital models were selected and the distance of straight line between the two points was calculated