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roots - international magazine of endodontology No. 3, 2016

canal preparation case report | 23 roots 3 2016 leadinguniversitiesandinternationalendo-special- ists, the renowned research department of the company developed an extremely versatile concept which meets various demands. The abbreviation ‘EDM’ stands for a specific manufacturing process named‘ElectricalDischargeMachining’,whichpro- duces a unique surface (Fig. 2). The spark erosion employed improves cutting performance, as the created structure can be compared with the ser- rated edge of a knife you use for cutting bread at home. Due to its special material properties, the file isvirtuallyunbreakableandpredestinedfordentists whorequirefastandreliableresultsusingareduced file sequence. In the case described we benefitted first and foremost from the so-called ‘Controlled Memo- ry’-effect (CM): similar to classical stainless steel files,HyFlexfilescanbepre-bentandconsid- erably help in preparation of distal molars (Fig.3,4).Atthesametimetheydonotbounce backlikeclassicNiTifiles,whichmeansthatthey moveinanoptimalwayinthecentreofthecanal. During autoclaving, reusable CM-treated files returntotheirinitialshapebecausetheyarenot plastically deformed. Due to the special situa- tion of the patient the pre-bent EDM files were the only files that would fit in the limited work space. Interestingly, the 25 mm EDM file fit in a space that would not allow a 21 mm traditional rotary NiTi. To create a suitable glide path, both mesiobuccal and mesiolingual canals were handfiled to a size 15 file. All pulpal tissue was removed after opening the pulpchamberandcanalclearancewascheckedthor- oughly. For the actual preparation, the use of a uni- versal EDM file in ISO size 25 totally sufficed (Fig. 5). With the flexible file we were able to instrument the mesialcanalstoaworkinglengthof22mm.Keeping its pre-bent shape, the instrument permitted to work without any stress and when the apex was gaugedinthedistalcanal,asize30handfileseemed to fit in quite comfortably. Consequently, a 40/0.04 HyFlex EDM finishing file was used to enlarge the apicalaspectofthetwodistalcanals.Itisimportant to point out that thorough irrigation was per- formed with sodium hypochlorite between every file. At the end of the procedure the canals were ir- rigated with NaOCI, EDTA and CHX under acoustic streaming. The canals were then dried via mi- crosuctionfollowedbytheinsertionofthecor- respondingpaperpoints.Intheend,thecanals were obturated with the help of the traditional warm vertical compaction technique (Fig. 6).The pulpal floor was sealed with a layer of glass iono- mer, sponge pellet (to act as a spacer) and a dual-­ curedtemporaryfillingmaterialconsistingofzinc oxide and zinc sulphate over the top. A post-­ op radiograph was obtained (Fig. 7) and after the successfulendodontictreatmentthepatientwas subsequently referred to his general dentist for the definitive restoration of the tooth. Fig.3: Pre-bendable EDM File 60/.02. Fig.4: Pre-bent EDM File 60/.02. Fig.5: HyFlex EDM One File. Fig.6: Post-op (clinical) situation. Fig.7: Post-op situation. Fig.3 Fig.6 Fig.4 Fig.7 Fig.5 32016

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