Figure 2.

(a) 1.4, first upper right premolar, longitudinal section of the marginal periodontal tissue, buccal surface original US image, gray scale; (b) 3D visualization: red, green, blue lines—cross-sectioning plane direction on the 3 axes; (b′). first semi-automatic segmentation: white—tooth crown, yellow tooth root, dark red—gingiva, light red—cortical bone; (c) 3D visualization using corrected masks; (c′) segmentation after correction: white—tooth crown, yellow tooth root, dark red—gingiva, light red—cortical bone.