September 2007Irish Dentistxx

as CBVI or CBVT were usedto differentiate thisconnection with medical CT.In this article, CBVI is used tocontinue the differentiation.

Descriptions of CBCTdevices for dentistry firstappeared in the late 1990swith reports from Italy andJapan describing thedevelopment of prototypemachines (Mozzo P et al,1998; Arai Y et al, 1999). Thefirst devices to becomecommercially available werethe Newtom QR 9000 (QRItalia, Verona, Italy) and the3DX Accuitomo (J Morita,Kyoto, Japan), which wereinitially introduced into theEuropean and Asian markets.These were soon followed bythe MercuRay (Hitachi, Japan,Twinsberg, OH, USA) and thei-CAT (Imaging Sciences,Hatfield, New Jersey, USA).All of the devices are capableof providing complete orpartial skull fields of view(FOV) except for the 3DXAccuitomo, which is aregional quadrant device witha field size of 40 x 30mm.

Currently, there areapproximately a dozendifferent machines eitheravailable, receivinggovernment approval or indevelopment (see Table 2).Some of the recent machineshave specifically targeted alimited FOV favouringregional, quadrant and dentalarch imaging similar to theinitial Accuitomo device. Suchan approach appears directedtoward providing cost-effective 3D imaging for thegeneral practice market(Farman AG, Levato CM,Scarfe WC, 2007; Miles DA,

The hallmark of dentistry inthe new millennium is‘computer assisted dentistry’and nothing characterises thismore than the impact 3Dcone beam computed volumeimaging/tomography(CBVI/CBVT) has had upondiagnosis, treatment planningand direct delivery of patientdental care.

In less than a decade, CBVIhas revolutionised oral andmaxillofacial radiology.Although development wasinitially directed towardsmulti-planar viewing fordental implant andorthodontic treatmentplanning, secondaryapplications in other areascontinue to expand becausedentists find they are nolonger confined to 2D,greyscale imaging and itprovides informationpreviously unobtainable (seeTable 1).

The intent of this article isto provide a brief overview of

dental CBVI technology andexamples of applications.While this technology hasbeen almost universallydescribed as CB computedtomography (CBCT), use ofthis term associated with theintroduction of this

technology created someconcerns that this was inreality a medical device and,as such, should not bedirectly available to dentistsfor operation. This wasparticularly a concern in theUSA and various terms such

CLINICAL

Cone beam volume imaging (CBVI) 3D applications for dentistry

Robert A Danforth and Dale Miles discuss the impact of cone beam volume imaging on dentistry

Robert A Danforth DDS is aDiplomate of the AmericanBoard of Oral andMaxillofacial Pathology andan Associate Professor ofClinical Sciences at theUniversity of Nevada LasVegas School of DentalMedicine.

Dale Miles DDS, MS,FRCD(C) is a Diplomate ofthe American Board of Oraland Maxillofacial Radiologyand an Adjunct Professor atthe Arizona School ofDentistry & Oral Health andthe University of Texas atSan Antonio.

Table 1: Current dental applications of CBVI

1. Primary applications

Pre-surgical implant site assessment

Inferior alveolar nerve location

Alveolar ridge configuration

Spatial relationships of anatomical structures

Surgical guide construction

Orthodontic assessment

Cephalometric and space 1:1 analysis

Temporomandibular joint evaluation

Multi-planar views, dentition relationship

Extraction cases

Impactions, third molars/nerve location, canines

Supernumerary teeth

2. Secondary applications

Paranasal sinus evaluation

Airway studies for sleep apnoea

Visualisation of jaw pathology

Trauma evaluation

Endodontic evaluation

3D virtual models

TADs (Temporary anchorage devices)

Other CAD/CAM devices

IR Sept Danforth 8/8/07 16:08 Page 1

Danforth RA, in press;Hayakawa, 2007).

How does it work? Why is it abetter option for dentistrythan medical computedtomography (CT)?Most of the CBVI ‘stand-alone’ devices look like apanoramic machine and thepatient either sits or standsduring the examination. Bycontrast, the NewTom 9000,NewTom 3G and the newerSkyView machines look likemini medical CT scannersand the patient lies in thesupine position. However,the newest version of theNewtom VG, marketed byDent-X/AFP, will be a stand-up version. While somecompanies have previouslyproduced panoramicmachines, currently only thePlanmeca ProMax CBVT isactually ‘upgradeable’ froman existing panoramicplatform.

Depending upon theimaging device, image

capture is generally a single190º-360º scan sweeparound the patient’s head.The X-ray beam is a ‘conebeam’ shape aimed at a solid-state flat panel detector thatcovers the desired imagevolume in a single scan. The‘fan-shaped beam’ employedin traditional medical CTrequires multiple repeatedslice scans to accomplish asimilar image volume(Figures 1a and 1b).

This single scan CBVIapproach is very successful atdecreasing the patient’sabsorbed X-ray dose from sixto 15 times during the 3Dimaging examination whencompared to medical CT(Farman AG, Levato CM,Scarfe WC, 2007).

The cone beam scanresults in several hundreddimensionally accurateisotropic images of thepatient from differentpositions around the scanrotation. Data is immediatelytransferred to the computer,

which reconstructs it, inapproximately three to sixminutes depending upon themachine, into the anatomicalvolume for viewing at aprecise 1:1 ratio withaccurate dimensionalmeasurements within1/10mm made acrossdifferent tissue planes.

Once reconstructed, multi-planar viewing of theanatomical volume isaccomplished with theimaging software. Volumedata is saved in a DICOM(Digital imaging andcommunication in medicine)file format to facilitatesharing images betweenclinicians and other imagingrelated services.

Most manufacturers alsoprovide a simpler ‘user’ PCviewing program thatcontains basic 3D imagingtools. This allows referralsources to participate inlimited 3D imaging withouthaving to purchase expensivesoftware. For clinicians whowish to plan their implantcases more actively, thirdparty software is available ata wide range of cost.

Applications and a new perspective for interpretation,diagnosis and treatment planningThe results of computer-generated 3D visualisation ofmulti-planar images are newapplications that improveinterpretation, diagnosis andtreatment planning.

Imaging for orthodontic

and dental implants areprime examples. Full volumeCBVI data for orthodonticshas spawned new research in

September 2007Irish Dentist xx

Table 2: CBVI devicesand manufacturer

2007

1. NewTom 3G, VG: Dent-X,

Elmsford, New York, USA

2. Accuitomo 3DX: J Morita, Kyoto,

Japan

3. i-Cat: Imaging Sciences (Danaher

owned), Hatfield, Pennsylvania, USA

4. CB MercuRay, CB Throne: Hitachi

Medical Systems, Twinsberg, OH, USA

5. Iluma: Imtec Corporation (Kodak

distribution), Ardmore, Oklahoma,

USA

6. Galileos: Sirona Dental Systems,

Bensheim, Germany

7. ProMax 3D CBVT: Planmeca,

Helsinki, Finland

8. SkyView: MyRay Dental Imaging,

Imola, Italy

9. TeraRecon: Yoshida Dental

Manufacturing, Tokyo, Japan

10. Alphard and PSR900N: Asahi

Roentgen, Kyoto, Japan

11. Scanora 3D: Soredex (PaloDex),

Tuusula, Finland

12. PicassoPro: eWoo (Gyeonggi-do,

Korea)

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September 2007xx Irish Dentist

CLINICAL

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IR Sept Danforth 8/8/07 16:08 Page 3

the orthodontic 1:1 ratiocephalometric measurementsfor treatment planning andseveral software programshave been developed for thispurpose (Figure 2).

There has also been atremendous impact upondental implant treatment andtreatment planning. Arch andridge configuration, locationof the nerve canals and sinuscavities can now bespecifically identified prior tosurgery, thus decreasingsurgical uncertainty andpotential patient morbidity(Figures 3a and 3b).

Besides mere visualisationof cross-sectional imaging ofjaw site locations, innovativesoftware programs have beendeveloped to make customprecision surgical guides,virtual models and laser-generated resin models, all ofwhich advance treatmentplanning and assist deliverycapabilities (Figure 4).

The advantage of theseinnovative changes is thatthey are relatively cost-effective and readily availableto the dentist. Directfabrication of dentalappliances from CBVI datausing CAD/CAM (computerassisted design/computerassisted manufacturing)systems would seem a nextprogressive development.

Beyond dental – 3D image volume produces new interpretation responsibility Although CBVI has createdexciting new 3D methods fordental applications, it has alsocreated increasedresponsibility for imageinterpretation. Unlikesuperimposed 2D imaging, alarge volume of viewablecollected patient data existsoutside of the specific regionof interest (ROI) in the multi-planar sections. Such imagedata must be viewed in the X,Y and Z planes to ensure that acomprehensive evaluation hasbeen performed anddocumented (Miles DA, 2006).Failure to recognise these or toact upon them could result invarious pathologic conditionsgoing undetected that could

have a negative outcome oneither the provided treatmentor, worse, patient health andlongevity.

September 2007Irish Dentist xx

Table 1, part 2 indicatesthat sinus and airway areapplications for evaluating thepresence of conditions

involving pathologic lesions,sleep apnoea or head andneck artery calcifications. Insome cases, these may be

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IR Sept Danforth 8/8/07 16:08 Page 4

September 2007xx Irish Dentist

secondary/incidental but life-threatening findings that aremost likely located outsidethe jaws in non-ROI 3Dmulti-planes. As such, manydentists may not be asfamiliar or comfortable withlooking for or interpretingthese conditions.

Despite any unfamiliarity,many recent reports(Friedlander AH, Garrett NR,Norman DC, 2002; Miles DA,Craig RM, 1983; Almog DMet al, 2002; Magliocca KR,Helman JI, 2005; Kumar V etal, 2007) indicate dentistryhas a role in such conditionsas: • Airway sleep apnoeaproblems• Sinus conditions • Bisphosphonate jawosteonecrosis• Awareness of carotid andother arterial calcifications asan indicator of potentialstroke or advanceddiabetic/renal problems.

These are examples ofexpanded regions of concernand responsibility whereCBVI can assist detection ofthese conditions. In thesecircumstances, referral to adiagnostic imagingradiologist/specialist for aninterpretative report of the3D data volume isrecommended (Figures 5a, 5band 5c).

Conclusion Any clinician reviewing theapplication list in Table 1knows the limitationsimposed by 2D imaging in a3D world when interpretivediagnostic dilemmas arise inthese areas. The length of thelist indicates that, actually, noaspect of dentistry is freefrom such dilemmas. UntilCBVI, when confronted withsuch situations, clinicianseither chose medical relatedCT imaging or continued to

CLINICAL

rely upon their traditionalinterpretation of 2D imagingdespite inherentdisadvantages.

CBVI imaging providesrelief for clinicians from 3Dmental reconstructions byusing outstanding computer-assisted 3D imagingtechnology for multi-planarimage visualisation, diagnosisand treatment planning.

The CBVI data obtained issimilar to that from a high-end medical CT scan, but at alower financial cost to thepatient and at a muchreduced radiation dose to thepatient (Ludlow JB et al,2006).

Since these devices arebecoming widely available inboth dental practices anddental imaging centres,reliance upon experience-based guess-estimations isbeing replaced by accurateimaging technology. As such,treatment outcomes areimproved and both patientsand dentistry benefit.

Despite these obviousadvantages, comprehensive3D image evaluationassociated with CBVI is a newresponsibility for dentistry

that must be accomplished inorder to comply with theethics of comprehensivepatient care.

ReferencesAlmog DM et al (2002)

Correlating carotid arterystenosis detected bypanoramic radiography withclinical relevant carotidartery stenosis determinedby duplex ultrasound. OralSurg Oral Med Oral Path OralRadiol Endod 94: 768

Arai Y, Tammisalo E et al(1999) Development of acompact computedtomographic apparatus fordental use. DentomaxillofacRadiol 28: 245-8

Farman AG, Levato CM,Scarfe WC (2007) A primeron cone beam CT. InsideDentistry 1: 90-93

Friedlander AH, Garrett NR,Norman DC (2002) Theprevalence of calcifiedcarotid artery atheromas onthe panoramic radiographsof patients with type 2diabetes mellitus. JADA 133:1516-23

Hayakawa Y (2007) Newlyadded oral and maxillofacialradiology imagingtechnologies. AADMRTwinter newsletter

Kumar V, Pass B, et al (2007)Bisphosphonate-relatedosteonecrosis of the jaws. JADA (138): 602-609

Ludlow JB, Davies-LudlowLE, Brooks SL, HowertonWB (2006) Dosimetry ofthree CBCT devices fororal and maxillofacialradiology: CB Mercuray,NewTom 3G and i-CAT.Dentomaxillofac Radiol 35:219-226

Magliocca KR and Helman JI(2005) Obstructive sleepapnoea: diagnosis, medicalmanagement and dentalimplication. JADA 136:1121-1129

Miles DA and Craig RM(1983) The calcified facialartery: a report of itspanoramic appearance andincidence. Oral Surg 55(2):214

Miles DA (2006) Clinicalexperience with cone beamvolumetric imaging: report offindings in 381 cases. USDentistry 1(1): 39-41

Miles DA, Danforth RA (inpress) A clinician’s guide tounderstanding cone beamimaging, PennWell

Mozzo P, Procccacci A et al(1998) A new volumetricCT machine for dentalimaging based on the conebeam technique:preliminary results. EurRadiol 8: 1558-64

For more information onCBCT and volumetric imagesgo to www.learndigital.net.

Table 3: Viewing software for clinicians

SimPlant: Materialise, Leuven, Belgium

VIP (Virtual Implant Placement): Implant Logic, Systems, Cedarhurst, NY, USA

V Implant, CB Works, Accurex, On Demand 3D: CyberMed International, Seoul,

Korea

In Vivo: Anatomage, San Jose, CA, USA

NobelGuide: Nobel Biocare, Göteberg, Sweden

Look out for our special supplement on implants in the next issue of Irish Dentist. To include

your company details, send 150 words plus an image to siobhan.lewney@fmc.co.uk today.

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