CODS Journal Vol-5 Issue-2, September 2013

CBCT IN CONSERVATIVE DENTISTRY ANDENDODONTICS - A REVIEW

Dr. VASUNDHARA SHIVANNA, M.D.s.,Principal, Professor & HeadEmail: drvasundhara56@gmail.com

Dr. G.B SHIVAMURTHYProfessor

Dr. PRAKASH LOKHANDEAsst. professor

Dr. SAURAV KR SRIVASTAVAPost graduate student

Department of Conservative Dentistry and Endodontics,College of Dental Sciences & Hospital, Davangere, Karnataka.--- ~ ~~~

ABSTRACT: Cone beam computed tomography (CBCT) has been specifically designed to produceundistorted three-dimensional information of the maxillofacial skeleton, including the teeth and theirsurrounding tissues with a significantly lower effective radiation dose compared with conventional com-puted tomography (CT).The system overcomes many of the limitations of conventional radiography byproducing undistorted, three-dimensional images of the area under examination. These properties makethis form of imaging particularly suitable for use in endodontics. The clinician can obtain an enhancedappreciation of the anatomy being assessed, leading to an improvement in the detection of endodonticdisease and resulting in more effective treatment planning. In addition, CBCT operates with a significantlylower effective radiation dose when compared with conventional computed tomography (CT). The aim ofthis paper is to review current literature on the applications and limitations of CBCT in the management ofendodontic problems.Keywords - cone beam computed tomography, conventional radiography, Endodontics

INTRODUCTION: CBCT stands for Cone beamcomputed tomography and is also known as conebeam volumetric imaging (CBVI) or cone beamvolumetric tomography (CBVT). Diagnosis isdefined as the art of distinguishing one disease fromthe other. I Radiographic imaging is essential indiagnosis, treatment planning and follow-up inendodontics. The interpretation of an image can beconfounded by a number of factors including theregional anatomy as well as superimposition of boththe teeth and surrounding dentoalveolar structures.As a result of superimposition, periapical radiographsreveal only limited aspects, a two-dimensional view,of the true three-dimensional anatomy.PAdditionally, there is often geometric distortion of theanatomical structures being imaged withconventional radiographic methods.Cone beam CThas the ability to eliminate the superimposition ofstructures that normally overlap in two dimensionalradiography. 1

CBCT IN CONSERVATIVE DENTISTRY AND ENDODONTICS - A REVIEW

A small- or limited-volume cone beam-computedtomography imaging technique can produce accurate3-D Images of the teeth and surroundingdentoalveolar structures. 2,3,4

CBCT is a new application of CT that generatesthree-dimensional (3D) data at lower cost andabsorbed doses than conventional CT found in thepractice of medical radiology. Data from thecraniofacial region are often collected at higherresolution in the axial plane than those fromconventional CT systems.' In addition; these systemsdo not require a large amount of space and can easilyfit into most dental practices today.MECHANICS:CBCT is accomplished by using a rotating gantry towhich an x-ray source and detector are fixed. Adivergent pyramidal- or cone-shaped source ofionizing radiation is directed through the middle ofthe area of interest onto an area x-ray detector on theopposite side of the patient.The x-ray source and detector rotates around a fixedfulcrum within the region of interest.

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COOS Journal vei-s Issue-2, September 2013---~--~APPLICATIONS IN CONS AND ENDO:CARIES DIAGNOSIS:The detection of proximal and occlusal surface cariesby conventional intraoral 2D methods hasdemonstrated only low-to-moderate sensitivity,butslightly better specificity, and high observer variability[7-11]. Recent work with benchtop-based local orlimited CBCT (LCT) systems has demonstrated thepotential for caries detection and depthcharacterization by high-resolution systems'!".Akdeniz and colleagues, using 41 teeth, histologicallyverified ground teeth, and all image planes for viewingfound that Limited volume CBCT was superior forcaries depth assessment when compared with StoragePhosphor and film. 13

ENDODONTICS:

During the exposure sequence, hundreds of planarprojection images are acquired of the field of view(FOV) in an arc of at least 1800

• In this single rotation,CBCT provides precise, essentially immediate andaccurate 3-D radiographic images. As CBCT exposureincorporates the entire FOV, only one rotationalsequence of the gantry is necessary to acquire enoughdata for image reconstruction."VOLUME SIZE:The dimensions of the Field of view (FOV), or scanvolume, are primarily dependent on the detector sizeand shape, beam projection geometry and the ability tocollimate the beam. Collimation of the primary x-raybeam limits x-radiation exposure to the region ofinterest. Field size limitation therefore ensures that anoptimal Field of view can be selected for each patientbased on disease presentation and the regiondesignated to be imaged. In general, the smaller thescan volume, the higher the resolution of the imageand the lower the effective radiation dose to thepatient. As the earliest sign of a periapicalradiographic finding suggestive of pathosis isdiscontinuity in the lamina dura and widening of theperiodontal ligament space, it is desirable that theoptimal resolution of any CBCT imaging system usedin endodontics not exceed 200llm-the average widthof the periodontal ligament space." The principallimitation of large Field of view(FOV) cone beamimaging is the size of the field irradiated. Unless thesmallest voxel (volumetric pixel) size is selected inthese larger FOV machines, there will be reducedresolution compared to intraoral radiographs orlimited-volume CBCT machines.For most endodontic applications, limited or focused

Field of view (FOV) CBCT is preferred over largevolume CBCT for the following reasons:1. Increased resolution to improve the diagnosticaccuracy of endodontic-specific tasks such as thevisualization of small features includingcalcified/accessory canals, missed canals, etc.2. Highest possible resolution.3. Decreased radiation exposure to the patient.

(compared to medical ct,it is only 40-500uSv)4. Time savings due to smaller volume to be

interpreted.5. Smaller area of responsibility.6. Focus on anatomical area of interest. 6

In general, the use of CBCT in endodontics should belimited to the assessment and treatment of complexendodontic conditions such as:• Identification of root canal system anomalies anddetermination of root curvature.• Diagnosis of dental periapicalpathosis in patientswho present with contradictory or nonspecific clinicalsigns and symptoms, who have poorly localizedsymptoms associated with an untreated or previouslyendodontically treated tooth with no evidence ofpathosis identified by conventional imaging.• Diagnosis of pathosis of nonendodontic origin inorder to determine the extent of the lesion and its effecton surrounding structures.• Intra- or postoperative assessment of endodontictreatment complications, such as overextended rootcanal obturation material, separated endodonticinstruments, calcified canal identification andlocalization of perforations.• Diagnosis and management of dentoalveolar trauma,especially root fractures, luxation and/or displacementof teeth, and alveolar fractures.• Localization and differentiation of external frominternal root resorption or invasive cervical resorptionfrom other conditions, and the determination ofappropriate treatment and prognosis.• Presurgical case planning to determine the exactlocation of root apex/apices and to evaluate theproximity of adjacent anatomical structures.• Diagnosis of vertical tooth fractures• Detection of apical periodontitis."

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1. Localization of inferior alveolar canal: Gives theaccurate assessment of the position of the inferioralveolar canal in relation to the 3rd molar.2. Impacted teeth: CBCT is useful in surgicalplanning of impacted teeth, for accurate localization,an understanding of orientation, depth and angulationand appreciation of proximity and relationship to otheranatomic structures. Imaging protocol used is MIP.3. Fractured teeth: CBCT is useful identifyingfracture in the teeth which cannot be detected on aconventional radiograph.4. Root resorption: CBCT is useful in evaluating rootresorption especially on buccal and lingual surfaces ofthe teeth.5. TMJ : CBCT is useful in analysis and diagnosis ofbone morphological features, joint space and dynamicfunctions, degenerative and developmental anomaliesof condyle, ankylosis and rheumatoid arthritis.6. Fractures: CBCT demonstrates disruption anddiscontinuity of osseous structures. Bilateral linearoblique 10mm thick MPR images are created based onthe axial image and MIP applied.7. Craniofacial anomalies: In assessment ofdeficiencies in sutural closure and bone formationassociated with craniosynostosis.8. Cervical spine: Cervical anomalies caused due tofailure of formation, failure of segmentation andcombinations of both failure of formation andsegmentation can be assessed. e.g.Osteogenesisimperfecta, Craniofacial anomalies likeCrouzon and Pfeiffer's syndrome,Hemifacialmicrosomia, Goldenhar's Syndrome.9. 3 d virtual model construction10. paranasal sinus evaluation11. space analysis12. odontogenic lesion evaluation13. implant site assessment14. Miscelleneous: Valuable in the identification anddemonstration of tonsilloliths, salivary gland stones,calcified lymph nodes, carotid artery calcifications andother vascular calcifications. 14

ADVANTAGESOFCBCT:• Perhaps the most important advantage of CBCT inendodontics is that it demonstrates anatomic featuresin three dimensions that intraoral and panoramicimages cannot.

• Enhancements including zoom magnification,window/level adjustments, and text or arrowannotation can be applied. Cursor-drivenmeasurement algorithms provide the clinician with aninteractive capability for real-time dimensionalassessment.• Onscreen measurements are free from distortion andmagnification. It provides the clinician with anunparalleled visualization of the often complexrelationships and boundaries between teeth and theirassociated pathology and anatomic features within thealveolus and jaws, such as the maxillary sinus andmandibular canal and foramen."• Reduced size and cost around 114th to 11 5th ofconventional CT• High speed scanning: less than 30 sec• Low patient radiation dose: Range from 52 to 1025mSv i.e., equivalent to 4 - 77 panoramic radiographs.• Dose reduction of 96% to 51% compared toconventional head CT.• Interactive analysis - real time dimensionalassessment, annotation and measurements. 14

LIMITATIONS OF CBCT: Cone-beam technologybased on an image intensifier may allow the peripheryof the image to be distorted. To date, cone-beamtechnology gives little in the way of soft tissue detailand, although newer algorithms have been developedto improve this aspect, it in no way compares to thosecapable of conventional CT.15 A significant issue thatcan affect the image quality and diagnostic accuracyof CBCT images is the scatter and beam hardeningartifacts caused by high density adjacent structures,such as enamel, and radiopaque materials such asmetal posts, restorations and root fillingmaterials. 16,17 Additional artifacts that may obscureradiographic findings are patient movement duringthe scan and volume reconstruction.CONCLUSION:Conventional intraoral radiography providesclinicians with cost-effective, high-resolution imagingthat continues to be the front-line method for dentalimaging. However, it is clear that there are manyspecific situations where the 3-D images produced byCBCT facilitates diagnosis and influences treatment.

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Cone-beam CT is almost certainly going torevolutionize dental radiology and impact on almostall aspects of dental practice. A good knowledge aboutcbct will enhance the practitioner's ability to moreaccurate diagnosis and develop comprehensivetreatment plans.REFERENCES:1. Cotton TP, Geisler TM, Holden DT, Schwartz SA,Schindler WG. Endodontic applications of cone beamvolumetric tomography. J Endod 2007;33:1121-32.2. Patel S, Dawood A, Pitt Ford T, Whaites E. Thepotential applications of cone beam computedtomography in the management of endodonticproblems. IntEndod J 2007;40:818-30.3. Grondahl HG, Huumonen S. Radiographicmanifestations of periapical inflammatory lesions.Endod Topics 2004;8:55-67.4. Scarfe WC, Levin MD, Gane D, FarmanAG. Use ofcone beam computed tomography in endodontics. IntJ Dent 2009: 1-20.5. Ito K, Gomi Y, Sato S, et al. Clinical application ofa new compact CT-system to assess 3-D images for thepreoperative treatment planning of implants in theposteriormandible.A case report. Clin Oral Implants

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11. White SC, Yoon DC. Comparative performanceof digital and conventional images for detectingproximal surface caries. DentomaxillofacRadiol1997;26:32-812. KalathingaISM,MoIA, TyndallDA, et al. In vitroassessment of cone beamlocal computed tomographyfor proximal caries detection. Oral Surg Oral MedOral Pathol Oral RadiolEndod 2007;104:699-704.13. Akdeniz BG, Grondahl HG, Magnusson B.Accuracy of proximal caries depth measurements:comparison between limited cone-beamCT, storagephosphor and film radiography. Caries Res2006;40:202-7.14. Dr. Ambesh Kumar Rai ,Dr. Abhay Kumar Jain,Dr. Akram Ansari,Dr. Rekha Mittal.REVIEWARTICLE - CBCT: VISUALIZATION OF THIRDDIMENSION The orthodontic cyber journal, august201215. lain Macleod, Neil Heath; Cone-Beam ComputedTomography (CBCT) in Dental Practice. DentUpdate 2008; 35: 590-598.16. Mora MA, Mol A, Tyndall DA, Rivera E. In vitroassessment of local tomography for the detection oflongitudinal tooth fractures. Oral Surg Oral Med OralPath Oral RadiolEndod 2007;103:825-9.17. Katsumata A, Hirukawa A, Noujeim M,Okumura S, Naitoh M, Fujishita M, Ariji E, LanglaisRP. Image artifact in dental cone beam CT. Oral SurgOral Med Oral Path Oral RadiolEndod2006;101:652-7.

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