8/10/2019 cone beam computed tomography (CBCT)

1/1

Introduction

This issue ofSeminars in Orthodonticswill pro-

vide a basic overview of cone beam com-puted tomography (CBCT), a technology thathas gained rapid acceptance in dentistry in gen-eral and orthodontics in particular despite itscurrent relatively high price when compared

with alternative imaging methodologies.Until very recently, cephalometric analysis of

the maxillofacial complex for orthodontic diag-nosis and image guidance for treatment plan-ning was only determined from linear and an-gular measurements of two-dimensional (2D)cephalograms. For approximately three-fourthsof a century, these skull radiographsmade un-der standard projection conditionsrepre-sented the standard image format for the analy-sis of both bony and soft tissue landmarks fordiagnosis and for growth potential evaluation.Posttreatment cephalograms have also served toevaluate orthodontic treatment outcome andsuccess. 2D cephalograms have been utilized fortheir cost and radiation efficiencies as well as

their ease of use. However, such projection char-acteristics as magnification, superimposition ofbilateral anatomic structures, and distortion areinherent.

CBCT can eliminate the projection inaccura-cies inherent in 2D cephalograms, and can fur-ther provide accurate assessment of the cranio-facial structures in three dimensions withexposure sequences that are shorter than thosefor standard panoramic radiography, and onlyseveral times greater in dose than for one suchimage. The volume that is recorded can be used

to simulate multiple plain and tomographic pro-jections.

Nonetheless, there are issues that should beconsidered when deciding whether or not toinvest in CBCT for the orthodontist practice.

First, one must consider the risk versus benefit ofany procedure employing ionizing radiations,especially when the majority of recipients oforthodontic treatment are children and adoles-cents. Second, it must be remembered that whilethere are quite a number of individual case stud-ies that demonstrate beautiful reconstructions ofanatomic and pathologic structures from CBCTdata sets, there is at present no unequivocalevidence-based study of improved orthodontictreatment outcomes from using CBCT. Third,the orthodontic community has not yet devel-oped high yield selection criteria for the use ofCBCT in orthodontic planning. Fourth, the cli-nician must be made aware that there are re-sponsibilities in interpreting the full image vol-ume exposed during CBCT, and there is arelative dearth of specialist support in readingthese image volumes. The latter is complicatedby the archaic nature of practice governance viaseparate state licenses with restrictions on inter-state referral of image data sets between some

states without the actual physical presence of thepatient.

This set of articles includes separate compo-nents for the topics of dosimetry, image selec-tion criteria, legal issues, and a review of thetypes of incidental pathologic findings that arenot infrequently found in CBCT data sets. Inaddition, there are brief explanations of whatCBCT is and how it might be used in support oforthodontics. This set of articles should not beconsidered a final verdict and prescription.CBCT has been available for orthodontics for

slightly less than a decade. There are still manyquestions awaiting definitive answers.

Allan G. FarmanWilliam C. Scarfe

Bruce S. HaskellGuest Editors

2009 Elsevier Inc. All rights reserved.

doi:10.1053/j.sodo.2008.09.011

Seminars in OrthodonticsVOL 15, NO 1 MARCH 2009

1Seminars in Orthodontics, Vol 15, No 1 (March), 2009: p 1