Fig. 3. Maxillary and mandibular basal bone region and root position measurements. ra’ point, the projection points of the root apex to the basal bone plane. A, Maxillary basal bone region comprises 34 external and 30 internal boundary points. B, Mandibular basal bone region comprises 28 external and 22 internal boundary points. DE, the distance from the ra’ point to the external boundary; DI, the distance from the ra’ point to the internal boundary.
