Fig. 3

Definitions of parameters for the subject teeth on panoramic radiographs. A line from the apex of the second deciduous molar to the cemento-enamel junction (A) was used as the y-axis, which was defined as crown height, and the x-axis was perpendicular to it. The distance from the mesial to the distal surface of the second deciduous molar on the x-axis was defined as crown width (B). Furthermore, the distance from the distal surface of the first premolar to the mesial surface of the first molar was defined as the interdental space (C), and the distance from the line connecting the apex of the first premolar and the first molar perpendicular to it to the apex of the mandibular second deciduous molar was defined as the distance from the occlusal plane (D). A; crown height, B; crown mesiodistal width, C; adjacent interdental space, and D; distance from the occlusal plane