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cone beam1_2012 Fig. 4_iCATTM Fig. 5_NewTom VGTM Figs. 6a, 6b, 7_Three- dimensional rendering and the maximum intensity projection will undoubtedly demand new cephalometric landmarks and analyses. I 31 clinical technique _neuromuscular application I Withasingle10–20secondCBCTscanandalarge FOV (field of view), we now have the full 3-D volume oftheheadandneckfromNasiondowntoC4includ- ingapanoramic,TMJ’s,pharyngealairway,paranasal and maxillary sinuses, etc., with a single scan. Three- dimensionalrenderingandtheMIP(maximuminten- sity projection) in Figure 6 will undoubtedly demand new cephalometric landmarks and analyses (Fig. 7) in addition to enhancing patient understanding and acceptance. Three-dimensional data will continue to enhance our existing knowledge with: 1)A measureable assessment of bone quality and density (Hounsfield units). 2)The ability to measure arch widths before and after treatment (Fig. 8). 3)Actualimpacteddentitionorientationinthree- dimensions (Fig. 9). 4)Upper airway evaluation (Fig. 10). 5)Pharyngeal volumetric airway evaluation be- fore and after treatment (Fig. 11). 6)TMJmorphologyandcondylarposition(Fig.12). Yet,withthisnewtechnologycomesthepersonal responsibility to further one’s education on 3-D anatomy — an absolute necessity for a proper, com- prehensive neuromuscular diagnosis. We must also learn how to accurately create the necessary images from this single scan. For example with 3-D pans, we must increase the reconstructed cut-plane width to incorporate the coronoid processes to assess potential hyperplasia and impingement and to incorporate maxillary bone as well as basal bone for potential ossifications of the stylohyoid ligament (Eagles syndrome). Failure to do so will result in a myriad of false negatives and potential misdiagnoses. Propermappingoftheanatomyisnomorecritical than for the temporal mandibular joints, best illus- tratedinthebelowaxialviews.Thethreeaxialimages (Submental view) in Figures 13–15 are actually on the same patient, but demonstrate three different and distinct condylar morphologies. Which one would you map for your TMJ study? The answer is Figure 13. Figure 13 demonstrates bilateral kidney shaped condyles, while both Figures 14 and 15 are indicative of potential osteogenic degeneration. Too often, Figure 14 is mapped with the straight TMJ tool (Fig. 16), creating the false positive of bilat- eral avascular necrosis, as seen here in the bilateral coronal views (Fig. 16), an artifact with invasive consequences! The operator should have continued to Figure 13, and using the oblique or panoramic tool, drawn the necessaryBeziercurveincorporatingbothlateraland medial poles (Fig. 17). _Soft-tissue legalities There has been a great deal of discussion and unwarranted fear being disseminated by a few self- serving oral and maxillofacial radiologists in addi- tion to the manufacturers of smaller FOV systems. Implyingthatwearenowresponsiblefordiagnosing brain tissue! Three-dimensions do not change the fact that brain tissue maladies and diagnoses are not taught in dental school and that CBCT systems by their very naturearenottobeusedinlieuofamedicalCTorMRI for soft-tissue diagnoses. With the cephalograms I read, an image encom- passing more cranial anatomy than the typical large FOV CBCT scan, I see one or two fibrosarcomas in sella and the thyroid every month because I look for them. But I see few articles in our dental journals that address these very issues, and I suspect that our medical radiology journals also devote little ink to periodontal disease. Fig. 6a Fig. 6b Fig. 4 Fig. 5 Fig. 7 Richard W. Greenan is an internationally known X-ray authority and president of Imaging Systems Inc., the Academy for Ad- vanced Radiographic Studies, author of A Practical Atlas of TMJ and Cephalometric Radi- ology and has published in nu- merousjournalsandtextbooks on dental implants, orthodon- tics and TMJ radiology. Richard W. Greenan c/o Imaging Systems Inc. Ste. #100–104 111 Petrol Point Peachtree City, Ga. 30269 Tel.: (207) 495-2986 dick@goodxrays.com cone beam_contact