Cone Beam Computed Tomography: A Link with the Past, a Promise for the Future Mark G. Hans, Manish Valiathan, and J. Martin Palomo During the last quarter of the 20th century, changes in clinical orthodontics were largely driven by improvements in bracket design, attachment mech- anisms, and arch wire materials. This focus on the mechanical aspects of treatment led to decreased clinical interest in the underlying biology of facial growth and, for a time, craniofacial practitioners often ignored the bio in biomechanics. There was even more disappointment after the completion of the Human Genome Project. Although this project promised exciting possi- bilities for biologically based manipulation of the growing face, the resulting data were interesting but in most cases not clinically useful. In 2001, the introduction of low-cost, low-radiation dose, high-resolution cone beam computed tomography (CBCT) in clinical orthodontics created the potential for new discoveries in craniofacial biology and facial growth. This technol- ogy provides researchers and clinicians with the tools needed to study 3-dimensional changes in craniofacial anatomy associated with the growth process and clinical care. In the 20th century, radiographic cephalometry was a pioneering advance that led to many fundamental insights into the behavior of the face and neurocranium during growth. CBCT imaging prom- ises similar advances in the 21st century. However, to take advantage of this opportunity, clinicians will need to interpret 3D anatomic changes in the context of the underlying growth process. This paper presents a short history of imaging in orthodontics, reports on the current state of the art, and suggests 3 ways CBCT imaging may influence the future of the specialty. (Semin Orthod 2011;17:81-87.) © 2011 Elsevier Inc. All rights re- served. T he history of radiographic imaging in or- thodontics began in 1931 when B. Holly Broadbent invented the cephalometer (Fig 1, Table 1). 1 The first cephalometers were installed in the major teaching universities and growth study centers in the United States and Europe. Initially the technique was used to study normal growth of the craniofacial skeleton, and several major longitudinal growth studies were con- ducted between 1932 and 1970. 2 Publications were based on these longitudinal studies form the bedrock of our current understanding of the facial growth process. Before the invention of the cephalometer, knowledge regarding the pro- cess of facial growth was based heavily on skeletal material that was by its nature cross-sectional. The strength of the cephalometric technique was that it allowed the longitudinal study of changes in the growing face. A comparison was made by carefully tracing each radiograph, su- perimposing on relatively stable anatomic struc- tures in the cranial base, and visualizing the changes in the facial bones and teeth. In addi- tion to studying normal facial growth, superim- position also provided a reliable method to eval- uate the effects of orthodontic treatment on the growing face. The knowledge gained from cephalometrics changed the course of orth- Department of Orthodontics, Case Western Reserve University, School of Dental Medicine, Cleveland, OH. Address correspondence to Mark G. Hans, Case Western Reserve University, School of Dental Medicine, 10900 Euclid Ave, Cleve- land, OH 44106. E-mail: mark.hans@case.edu © 2011 Elsevier Inc. All rights reserved. 1073-8746/11/1701-0$30.00/0 doi:10.1053/j.sodo.2010.08.006 81 Seminars in Orthodontics, Vol 17, No 1 (March), 2011: pp 81-87