international magazine of oral implantology

I 21implants1_2011 special _ endo-implant algorithm I by advanced image receptor sensors. It is thus ideally suited for dedicated dento-maxillofacial CT scanning. When combined with application-specific software tools, CBCT can provide a complete solution for per- formingspecificdiagnosticandsurgicaltasks.Theim- agescanbere-slicedatanyangle,producinganewset ofreconstructedorthogonalimages,andstudieshave shown that the scans accurately reflect the volume of anatomicaldefects.ThelimitedvolumeCBCTscanners bestsuitedforendodonticsrequireaneffectiveradia- tion dose comparable to two or three conventional peri-apical radiographs and as such are set to revolu- tioniseendodontics(Fig.6).15,16 Three-dimensional pre-surgical assessment of the approximation of root apices to the inferior dental canal,mentalforamenandmaxillarysinusareessential to treatment planning. The ability of CBCT to diagnose and manage dento-alveolar trauma using multiplanar views, the determination of the root-canal anatomy andnumberofcanals,thedetectionofthetruenature andexactlocationofresorptivelesionsandthediscov- eryoftheexistenceofverticalandhorizontalfractures outweighconcernsaboutthedegreeofionisingradia- tionandtherisksposed.17 ProvidedCBCTisusedinsit- uations in which the information from conventional imaging systems is inadequate, the benefits are essen- tialforoptimisationofthestandardofcare. Patel reported that peri-apical disease can be de- tected sooner and more accurately using CBCT com- pared with traditional peri-apical views and that the truesize,extent,natureandpositionofperi-apicaland resorptivelesionscanbeaccuratelyassessed.18 Usinga newperi-apicalindexbasedonCBCTforidentification of apical periodontitis, peri-apical lesions were identi- fied in 39.5% and 60.9% of cases by radiography and byCBCT,respectively(p<0.01). Simon et al. compared the differential diagnosis of largeperi-apicallesionswithtraditionalbiopsy.There- sultssuggestedCBCTmightprovideafastermethodto differentiallydiagnoseasolidfromafluid-filledlesion or cavity, without invasive surgery.19, 20 In spite of the presenceofartefacts,thelearningcurverelatedtoim- age manipulation and the cost, CBCT will invariably be the accepted standard of diagnostic care and treat- mentplanninginendodonticsintheverynearfuture. _Access An improperly designed access cavity will ham- per facilitation of optimal root-canal therapy. If the orientation, extension, angulations and depth are in- accurate, retention of the native anatomy of the root- canal space becomes precarious. The requirements of accesscavitydesigncanbeachievedbyconceptualand technical regression of the existing configuration to that which one would logically expect to have seen priortotheinsultsofrestoration,functionandageing. Iftertiarydentinewereperceivedofas‘irritationalden- tine’ordystrophiccalcificationconsidered‘decay’,the chamber outline could be used to blueprint an inlay configurationfortheaccessdesignthatliterallyrepli- catesthevirgintooth(Fig.7). Removal of the existing restoration in its entirety and/or preliminary preparation of the coronal tooth structureforthesubsequentfullcoveragerestoration willidentifydecay,fractures,unsupportedtoothstruc- ture and expose the anatomy of the underlying root trunk periphery, which assists in discovery of the spa- tialorientationandmorphologyoftheroots.Thepulp Fig. 4a_Panel of anatomic preparations from the classic work by Walter Hess (The Anatomy of the root canals of teeth of the permanent dentition, London, 1925). Fig. 4b_In order to determine the number of root canals and their different morphology, ramifications of the main root canals, location of apical foramina and transverse anastomoses, and frequency of apical deltas, 2,400 human permanent teeth were decalcified, injected with dye and cleared (Vertucci FJ, 1984). Fig. 4a Fig. 4b