Applications of Cone Beam ComputedTomography in the Practice of Oral and
Maxillofacial SurgeryFaisal A. Quereshy, MD, DDS,* Truitt A. Savell, DDS, MD,†
and J. Martin Palomo, DDS, MSD‡
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roviding imaging in 3 dimensions, computed tomog-aphy (CT) has had a profound effect on surgical andedical practice since its introduction in 1973.1 Practi-
ioners at that time certainly marveled at the new tech-ology, but likely were at a loss as to how to apply it orhat exactly the images meant. It was only after years of
esearch, as well as the development of a whole newspect of radiology, that we have been able to apply thisechnology for the benefit of our patients.
In oral and maxillofacial surgery, we are accustomedo using CT in patients with trauma and pathologicalonditions in the hospital setting; however, in dentalractice, practitioners depend almost entirely on 2-di-ensional plain films. The applications and advantages
f CT in dentistry remain largely unrealized.Cone beam CT (CBCT) was first developed for use
n angiography. In 1998, Mozzo et al2 reported therst CBCT unit developed specifically for dental use,he NewTom 9000 (Quantitative Radiology, Verona,taly). Other similar devices introduced at around thatime included the Ortho-CT, which was renamed theDX (J. Morita Mfg Corp, Kyoto, Japan) multi-imageicro-CT in 2000.3,4 In 2003, Hashimoto et al4 re-orted that the 3DX CBCT produced better imageuality with a much lower radiation dose than theewest multidetector row helical CT unit (1.19 mSvs 458 mSv per examination).
eceived from the School of Dental Medicine, Case Western Re-
erve University, University Hospitals Case Medical Center, Cleve-
and, OH.
*Program Director, Department of Oral and Maxillofacial Surgery.
†Former Resident, Department of Oral and Maxillofacial Surgery.
‡Associate Professor of Orthodontics and Director, Craniofacial
maging Center.
Address correspondence and reprint requests to Dr Quereshy:
epartment of Oral and Maxillofacial Surgery, School of Dental
edicine, Case Western Reserve University, 2123 Abingdon Road,
2008 American Association of Oral and Maxillofacial Surgeons
278-2391/08/6604-0026$34.00/0
aoi:10.1016/j.joms.2007.11.018
791
CBCT machines have 2 major differences comparedith so-called “medical” CT scanners. First, CBCTses a low-energy fixed anode tube, similar to thatsed in dental panoramic x-ray machines. Second,BCT machines rotate around the patient only once,apturing the data using a cone-shaped x-ray beam.hese changes allow for a less expensive, smallerachine that exposes the patient to approximately
0% of the radiation of a helical CT, equivalent to thexposure from a full-mouth periapical series.5-8
All of the CBCT scanners currently on the market usehe same technology, with only slight differences. Theajor difference is in the detector used, either an amor-hous silicon flat-panel detector or a combination of an
mage intensifier and a charge-coupled device (CCD)amera. Both these technologies have been proven toe accurate and reliable and to provide sufficient reso-
ution for the needs of dental medicine (Fig 1).Within every field, the introduction of new technol-
gy raises several fundamental questions, including iden-ifying the practical applications of the new technologynd determining whether it is truly superior to existingodalities. These questions are not easily answered, but
equire research and comparison. This article exploreshe possible applications of this new CBCT technologynd the ongoing research in these areas, with the goal ofpplying CBCT data in an evidence-based manner.
mplant Dentistry
The advantages of CBCT in visualizing the alveo-us in 3 dimensions and making precise measure-
ents before surgery are obvious in the field ofmplant dentistry (Fig 2). With conventional pan-ramic radiography, it is not unusual to anticipatedequate bony support preoperatively, only to beisappointed in the reflection of tissue. Obviously,aving this information preoperatively greatly re-uces the likelihood of the need to change thereatment approach intraoperatively. This gives theurgeon the ability to anticipate implant placement
erms of bone height, bone width, nerve position,nd even objective measures of bone quality.9
With regard to a traditional panoramic radiography,he average machine produces approximately 25%agnification, which must be accounted for whenlanning implant placement. Preliminary studies onBCT, specifically the NewTom 9000, have con-luded that the CBCT image underestimates the actualistances; however, these differences were significant
IGURE 2. Images producedrom a single exposure for the pur-ose of dental implant planning.he images selected here are pan-ramic and cross-sectional viewsith the mandibular nerve marked,s well as a surface and radio-raphic (maximum intensity projec-
nly for the skull base. Imaging within the dentomax-llofacial regions was found to be quite reliable, dem-nstrating no significant differences.10 The fact thateasurements from the CBCT are routinely accurate
hroughout the maxilla and mandible makes this anxcellent modality for planning implant placement.11
Conventional multislice CT has been used for im-lant planning and in fabrication of a stent used in-raoperatively for precise implant placement in pre-
FIGURE 1. Some currently avail-able CBCT scan devices. A,NewTom 3G (courtesy of AperioServices, Sarasota, FL). B, i-Cat(courtesy of Imaging Sciences,Hatfield, PA). C, ILUMA (courtesyof IMTEC Corp, Ardmore, OK).D, ProMax 3D (courtesy of Plan-meca Oy, Helsinski, Finland). E,CB MercuRay (courtesy of HitachiMedical System America Inc,Twinsburg, OH). F, Dental CBCT(courtesy of TeraRecon Inc, SanMateo, CA). G, 3D Accuitomo(courtesy of J Morita USA, Irvine,CA). H, Sirona Galileos (courtesyof Sirona Dental Systems NorthAmerica, Charlotte, NC).
etermined locations. The stent can be fabricated onop of a CT image without the need for patient con-act, allowing for precise placement of implants, pre-abrication of the prosthesis and abutments, and de-ivery of the prosthesis on the same day as surgery.12
BCT images have similar capabilities with the bene-t of less radiation exposure to the patient.
ral and Maxillofacial Pathology
Conventional CT is used routinely in the diagnosis ofaxillofacial pathology. Given the higher resolution,
ower radiation dose, and lower cost of CBCT in imaginghe maxillofacial region, it stands to reason that CBCTan easily replace conventional CT in this regard. Three-imensional imaging of cysts and tumors of the maxil-
ofacial region can give the surgeon the vital informationecessary for planning surgery; with volumetric analy-is, this can help anticipate the need for and volume of aotential graft for reconstruction (Fig 3). CBCT data alsoan be useful in creating a stereolithic model of the areaf interest.
emporomandibular Joint Disorders
The diagnosis and treatment planning of temporo-andibular joint (TMJ) disorders often are quite chal-
IGURE 3. CBCT images of aatient with a mandibular cyst. A,esial view of right half of the man-
ible in a surface mode. B, Anterioriew of the mandible in the surfaceode (measurements in mm). C,
ingual view of the mandible in sur-ace mode (measurements in mm)., Radiographic cross-sectionaliew of the maxilla and mandible., Panoramic view.
enging. Although magnetic resonance imaging remains a
he gold standard for imaging the intra-articular compo-ents of the TMJ, evaluation of the bony components isften left to conventional panoramic radiographs. Pan-ramic radiographs can provide a general impression ofhe joint in 2 dimensions but have low sensitivity invaluating changes in the condyle, poor reliability, andow accuracy in evaluating the temporal components ofhe joint.13 The imaging offered by current CBCT ma-hines has been shown to provide a complete radio-raphic evaluation of the bony components of the TMJFig 4). The resulting images are of high diagnosticuality. Given the significantly reduced radiation dosend cost compared with conventional CT, CBCT mayoon become the investigational tool of choice for eval-ating bony changes of the TMJ.14
raniofacial Surgery
Treatment planning for patients with cleft lip andalate entails many unique considerations. Due to theoung age of the patients and concerns about radiationxposure, conventional CT is not always used. Timing oflveolar cleft repair is often determined based on pan-ramic and occlusal radiographs. Other considerations
nclude palatal expansion as well as segmental align-ent. CBCT should allow better evaluation of dental
ge, arch segment positioning, and cleft size compared
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ith traditional radiography (Fig 5). Volumetric analysisromises to offer better prediction in terms of the mor-hology of the defect, as well as the volume of graftaterial necessary for repair. Questions abound regard-
IGURE 5. CBCT images of aatient with a cleft palate. A, An-
erior view of the maxilla in theurface mode. B, Anterior view ofhe maxilla in the radiographicode. C, Occlusal view of theaxilla in the surface mode. D,cclusal view of the maxilla in the
ng the stability of the arch after grafting, the quality ofhe bone graft over time, and the effect on overall facialrowth; CBCT provides a means to investigate thesessues in depth.
FIGURE 4. Different possibleviews of the TMJ complex usingCBCT. A, Surface mode. B, Ra-diographic mode. C, Close up ofthe radiographic view. D, Cross-sectional view in the radiographicmode.
FIGURE 7. CBCT images of apatient with an impacted supranu-merary tooth. A, Anterior view ofthe maxilla in the radiographicmode. B, View of the right half ofthe maxilla in the radiographicmode. C, Surface view of the an-terior right segment of the maxilla.D, Anterior view of the maxilla inthe surface mode. E, Occlusalview of the maxilla in the radio-graphic mode.
Clinicians have long evaluated the usefulness of-dimensional imaging in orthodontics and orthog-athic surgery, with a major concern being theorrelation between soft tissue and hard tissuehanges.15 For decades, lateral cephalography haseen the standard modality for diagnosing skeletalnd dental deformities, as well as for use in surgicalrediction and treatment planning. These applica-ions are made possible by the early growth studies ofhe mid-1970s that set the stage for current cephalo-etric analysis and prediction.16,17 In like fashion, it
tands to reason that before a 3-dimensional modelan be reliably adopted for orthodontic and orthog-athic analysis and surgical prediction, extensive re-earch is needed to characterize the landmarks andelationships that this technology allows us to mea-ure.
As useful as cephalometric analysis can be, its im-ging accuracy is inadequate in such deformities asemifacial microsomia, severe facial asymmetries, andcclusal cant. Three-dimensional imaging of the hardnd soft tissue makes all of the data available (Fig 6);he only question is how best to apply and manipulatehat data for more accurate surgery and treatmentlanning.
mpacted Teeth
The identification, treatment planning, and eval-ation of potential complications of impacted teethre greatly improved by adding the third dimensionhrough CBCT. The site evaluation becomes notnly less invasive and less time-consuming, but alsoore complete. The relationship of impacted thirdolars to the mandibular canal, adjacent teeth, si-
us walls, and cortical borders is important diag-ostic information that can directly impact the out-ome of surgery.18
Using CBCT to locate and evaluate impacted cus-ids and supernumerary teeth seem to make the sur-ical procedure more efficient and less invasive (Fig).19 Because the anatomic structures adjacent to theegion of interest can be seen in 3 dimensions, thisdditional information may reduce the morbidity andotential complications during surgery, contributingo a better outcome.
In summary, with the continued decreasing cost ofBCT technology, it is only a matter of time untilBCT finds its way into the average oral and maxillo-
acial surgery practice. The increased diagnostic capa-
ility combined with the lower radiation dose alsoill help bring this technology into the mainstream.he applications described herein are merely the be-inning. We are now capable of obtaining signifi-antly more data to characterize a patient’s condition.he next step is to establish how best to use thesedditional data in the most effective manner.
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