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ePaper created 2016-01-20, 13:53:08 | version 1.38.0
I 49 industry report _ shaping canals I roots1_2015 was being impaired by the use of stainless-steel in- struments and this occurred more frequently with less skilled operators and more complicated clinical cases. According to a number of authors, shaping root canals with stainless-steel instruments gives risetomoreledgesthanwithNiTiinstruments,irre- spectiveofwhethertheyareusedmanuallyorfitted on suitable motors.1–3 This will lead to more failures in endodontic treatment. In one of their papers, BeruttiandColleaguesstressedthatunskilledoper- ators(students)causedmanymoredeformationsin themiddlethirdandapicalthirdoftherootcanalus- ing stainless-steel instruments than did skilled op- erators.4 However,thisproblemwasreducedforun- skilled operators using NiTi rotating instruments. In fact, the results obtained by students with NiTi rotating instruments were much better than those obtained by skilled operators using stainless-steel instruments.Basedonthesefindings,wedecidedto avoid the use of stainless-steel instruments and to start treatment with NiTi instruments from the first file inserted into the canal. But how do we work without going beyond the apex? On the one hand, stainless-steel instruments are the cause of the problem, especially with less skilled operators, and the more curved and complex the canal is, the more serious the problem. On the other hand, we cannot insert a rotating instrument unlessweknowexactlywherethetoothends.Wecan determine this using a device with an electronically controlled endodontic motor and a suitable elec- tronic apex locator. We have found such systems in the DentaPort ZX with a high-precision electronic apex locator and the TriAuto mini kit (Morita). The device is connected to the patient through a cable andtheinstrumentstartsrotatingonceitisinserted into the canal. It stops working when it reaches the apicalforamen.Wehavetestedtheprecisionofthese devices with a simulator and the results confirmed that the system is highly reliable (Fig. 1). Having solved one problem, we focused on re- ducing the fracture risk of instruments; the liter- ature helped us in this case too. We were able to greatly reduce this risk by creating a glide path5,6 and removing any coronal interference.7 At this point,ourtechnique,called“HybridConcept”,was starting to take form. We establish the glide path quickly using the thinnest rotating NiTi instru- ment available, #1 EndoWave MGP (Mechanical Glide Path; Morita). We can therefore take advan- tage of the integrated electronic control of the devices already mentioned. We follow the same procedure in case of narrow or very curved canals, using the #2 MGP (tip D of 15mm) and #3MGP (tip D of 20mm) files in very complex cases. Figs. 3a & b_An easy case: conventional endodontic treatment of a maxillary left first premolar (Dr Marco Vigna, Italy). Fig. 4_Flow chart of an easy root canal treatment. Fig. 3a Fig. 3b 800 rpm 600 rpm / 600 rpm 0.4 N/cm2 3 N/cm2 / 1.5 N/cm2 10/08 35/08 K-File 10/02 20/06 Fig. 2c 10/0835/08 K-File 10/0220/06