clinical report _ shaping system I and my shaping files working through those canals cut into a common terminal opening. The second apical portal of exit in the root was kept patent with a #15 K-file, the gutta-percha points were fitted into the confluence, and the second opening was filled during the Continuous Wave of Condensation Downpack. The canals were initially shaped with a single 20/.06 in three cutting cycles, followed by a 30/.06 GTX File to finish as the 20/.06 had no tip flute debris upon reaching length. The distal canal was more difficult because it had a sharply bent canal with a ledge at the apex of the curve (created by the previous dentist who treated the patient). Pre-bent, stainlesssteel K-files were used to bypass the ledge impediment and a series of files (sizes 15 to 30) were used in a light serial step-back technique to rough out the apical shape. I had used this technique to cut tapered-preparation shapes in root canals for about ten years, and although it was the only method we had prior to variably tapered NiTi shaping instruments, it was slow and tedious, and created less-than-perfect tapers in canals. So in this case, although it was necessary to cut an initial shape with this method, I wanted an apical taper that would improve the apical accuracy of obturation in the canal. The technique taught to me by Dr David Rosenberg, (a dear friend) who tragically passed away earlier this year and will always be an inspiration, in these situations is to pre-bend the NiTi shaping files with Endo-Bender pliers. While NiTi (even with its shape memory) is commonly thought to be impervious to bending, it actually requires greater flexure—about a 180 degree bend—to achieve a residual bend of approximately 30 to 45 degrees. This can be done to GT Hand Files or to GTX Rotary Files (I prefer using handpiece-driven files for this procedure). After a 30/.08 GTX File was bent and the directional indicator on the stop was aligned with the bend, I tapped the foot pedal until the bend on the file in the handpiece was in a distal direction, dropped it past the ledge impediment, and depressed the foot pedal. The file quickly cut to length and the canal was tactilely gauged at a 30 K-file size. However, the ledge was so large that it was virtually impossible to fit a gutta-percha cone beyond it, so this canal was filled with a GTX Obturator. These filling devices always move the sealer and gutta-percha ahead of the carrier. So, in this case I filled beyond the impediment by inserting the obturator to the ledge point in four seconds, thereby accelerating the apical movement of filling material ahead of the carrier by 3 to 4 mm. This was instead of the usual six- to eight-second insertion time, described in my typical GTX Obturator technique, necessary to limit the filling material to only end up 1 mm ahead of the carrier—which is obviously the goal when the carrier can be placed to a length 1 mm short of the terminus. This case was shaped with just two GTX Files in the reasonable curvature of the mesial canals. However, as is typical with difficult canals, the distal canal required four K-files and a single GTX File (Fig. 5). _Cases 3 and 4 The two cases shown in Figures 6 and 7 were treated by my good friend Dr Giuseppe Cantatore. As is typical of his GTX technique for virtually all canals, he negotiated each canal up to a K-file size 20, cut a 20/.06 GTX File to length, then cut a 30/.04 GTX File to length, and finished with a 30/.06 GTX File. Dr Cantatore is known for Figs. 6 & 7_Maxillary molars with S-shaped curves in the DB canals; note the MB root structure in Figure 6 with its narrow width and remarkable curvature. No anti-curvature brushing motion was needed because of the GTX File lands and their limited MFDs. These cases were filled with carrier-based obturation. (Courtesy of Dr Giuseppe Cantatore) Fig. 6 Fig. 7 roots 4 _ 2009 I 09