Fig. 3

Measurement of the mesial alveolar bone height of the second premolar before and after orthodontic treatment. (A) Reference planes for the current position in the three-dimensional (3D) view; (B) The orange line through the center of the canine root (red arrow) and the center of the third premolar’s mesial root (blue arrow); (C) The mesial alveolar bone height (the distance between point A and point B) of the second premolar before orthodontic treatment. The green line was rotated through the canine’s distal cementoenamel junction (CEJ) and the third premolar’s mesial CEJ; (D) The mesial alveolar bone height (the distance between point A and point B) of the second premolar after orthodontic treatment