cone beam international magazine of cone beam dentistry

I 23 industry report _ CBCT diagnostic potential I cone beam1_2014 alongtheaxisofthetoothismeasuredautomaticallyat sixmeasuringpointscircumferentiallyaroundthetooth (vestibularandoral,withmesial,centralanddistalmeas- urementsineachcase)togivea360-degreeevaluation ofcrestalbonestatus.Thedentino-enameljunctionand crestalalveolarboneserveasreferencelandmarks(Figs. 2a & b). In the case of multiple-rooted teeth, any possi- ble pathological furcation involvement can be clearly evaluated using a special 360-degree panoramic view andbymetricallymeasuringthedegreeoffurcationin- volvement(Fig.3).Allfindingscanbepresentedindivid- uallyingraphicortableformatasdesired(Figs.4a&b). _Imaging processes in dentistry: 2-D versus 3-D The main disadvantage of conventional 2-D image processing is the 2-D display of 3-D anatomical struc- tures. Important morphological aspects and their pathologicalchangestothetooth-supportingalveolar ridge can only be detected at advanced stages of de- terioration, or perhaps not at all, owing to overlapping images.Theamountofboneavailablecanonlybedeter- minedwithacertaindegreeofaccuracyintheapprox- imal spaces. The detection and quantitative determi- nationofdouble-totriple-walledbonedefectsisoften adiagnosticchallenge,eveninthecaseofhigh-quality X-rayimages.7Inthiscontext,coPeriodontiXisintended to be a valuable tool that allows precise and standard- isedevaluationof3-Dcross-sectionalimagesaspartof periodontaldiagnosticsinadditiontotheindispensable clinical exploration. The focus is the measurement of available bone mass prior to, during, and after treat- ment,aswellasmonitoringfollowingtheregenerative treatmentofverticalperiodontaldefectsandfurcation involvement,forexample. _Limitations of CBCT Artefacts A major problem with all cross-sectional imaging methods is the generation of image artefacts. Typically, high-densitystructuralelementsintheobjectinvestigat- ed (e.g. metallic restorations, root pins, implants, osteo- synthesisplates)leadtoobliteratingandhardeningarte- facts in beam direction.13 Under certain circumstances, thesemayimpairthediagnosticassessmentofdirectlyad- jacentstructures(e.g.approximalspaces,peri-implantre- gion),andmayinpartevenmimicpathologicalstructures. Effectiveradiationdose The radiation dose for patients undergoing dental CBCT largely depends on the CBCT system, the type of detector used, and the exposition parameters of the X-ray itself. As a rule, image-intensifier systems pro- duceaslightlylowerdosethanflat-paneldetectorsys- tems do.11 The effective dose, in terms of risk manage- ment, can be reduced considerably by selecting an im- agevolumeadjustedtotheareaofexploration.14 Scien- tificstudieshaveshownthatthedose15–18 ofCBCTmay well be similar to the magnitude of intra-oral film sta- tus for a single tooth (with up to 14 individual images) and that CBCT may offer considerably higher informa- tion content in direct comparison.6 Nonetheless, strict indications according to the ALARA (as low as reason- ably achievable) principle should be adhered to under all circumstances when employing CBCT to minimise theexplorationriskforthepatient. Imagingaccuracyandprecision Whendefiningtheprecisionandmeasuringaccuracy forperiodontaldiagnostics,acertaindegreeofdeviation between the clinical situation and the resulting radio- logical information is inevitable but can be regarded as Fig. 3 Fig. 4a Fig. 4b CBE0114_22-24_Fleiner 03.02.14 11:53 Seite 2