Figure 18a. Images in a 46-year-old man with periodontal disease causing bone resorption of the right and left first molar root furcation and with endodontal disease causing periapical radiolucency in the left central incisor. (a) On the conventional dental radiograph, roots are superimposed, making it difficult to determine which roots have bone loss and whether periodontal disease affects root furcation. Bone resorption (arrowheads) is depicted along the sides of the roots. (b) Transverse CT image more easily reveals that radiolucency due to bone resorption involves the root furcations of the first molars (short arrows). Note also the large periapical radiolucency (long arrow) in the left central incisor caused by endodontal disease. (c) Cross-sectional CT image optimally shows the radiolucency in the first molar root furcation (arrows). Dentin (d), dense enamel (e), and pulp (p) are also nicely depicted. m = maxillary sinus. (Reprinted, with permission, from reference 8.)