Young Bui
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’M WRITING this article because people have asked me if SafeSiders® can be used for every case. They have tried both rotary NiTi and SafeSiders and feel that certain cases require certain systems. Well, I can only speak of two systems that I have actually used. I have had three years’ experience in using rotary NiTi, specifically the Profiles GT, from 1998–2001. I have had great success with them and still think that rotary NiTi is a great system. I have had many separations (of both old and new files) when using the system on really curved canals. I do not know what improvements have been made to the instruments since 2001 to reduce separation, so I will not even attempt to discuss why they break. I will first explain my method of treating extremely curved canals with the SafeSiders, which I am currently using, and then I will explain how to perform the process with rotary NiTi for those who would rather use that system.
The reason for transporting the canals in extremely curved roots, according to my own experience (there is no clinical study to support this reasoning), is not determined by any choice of files or system but by debris blockage. Instructors can tell me that their files or reamers do or do not have end cutting. I can transport any canals using any files or reamers out there, and I have done that enough times to figure out how to prevent perforation.
The SafeSiders Technique
The first step in doing RCT in curved canals is getting the # 6 or # 8 reamer to the apex. If you cannot do that, then send the case out and don’t even bother to try it. Next, flood the chamber with NaOCl to give you lubrication and a medium to remove debris from the instrumentation. Now here is the most important step of all: achieving patency. I don’t know how else to stress this point. If you block yourself out, you will be more than likely to transport or perf out the root. To avoid blocking yourself out, instrument the canal from the # 6 up to the # 25 reamer 1 mm beyond the apex. I know what some of you are thinking right now: He must be an idiot! The patient is going to have so much post-op pain from the procedure. Well, the patient will be more than happy to have a couple of days of pain that an anti-inflammatory can help rather than having to get an apico or extraction because you transported or perfed out. Don’t be cheap with the reamers, either. I normally go through four or five # 6, # 8, and # 10 reamers just to widen the canal and keep it patent. I go through another three or four # 15, # 20, and # 25.
The way to prevent debris blockage is to go back to the # 6 reamer after every larger size reamer you used. Next, use the # 2 Gates Glidden and open up the canal. Do it in a pecking motion, not applying constant apical pressure. If you feel resistance, then stop. Irrigate the canal and establish patency with the # 10 or # 15 reamer. Never use the # 1 GG. When these guys break, they break at the tip. Good luck in removing them. Next, use the # 2 Peeso reamer in the same manner as the GG. Do not lean against the opposite wall to create the straight-line access. You will either thin out the furcal wall or strip perf the tooth. Just let the canal dictate the path. The Peeso will automatically straighten out the coronal portion for you because of its stiff shank. Again irrigate and establish patency with the # 10 or # 15 reamer.
Now you have only two more stainless steel reamers to go. My reason for preferring the SafeSiders reamers over regular reamers is that they are more flexible even at the larger sizes. You can use the # 30 and # 35 SafeSiders reamers in a reciprocating handpiece, and they will take the curve without distortion. Next, take the 30/.04 NiTi to the apex. This one should get there easily without any problem. The one you should be concerned about is the 25/.08 NiTi. This is the one that will smooth out the bottleneck effect of the Peeso to give the canal a smooth taper. This Peeso is the one that will break on you if you are not careful. I have broken a few, so I know what I’m talking about. I like to use this with my hand instead of the reciprocating handpiece because I can gauge the amount of stress being exerted (maybe that’s why they break on me). If you are not good at reciprocating with your thumb and finger, then I suggest that you use the handpiece. The reason for most separations is turning in only one direction. I notice this effect a lot when I teach endodontic technique to general dentists. Try to get the instrument down to the apex or at least 1–2 mm away. Don’t force it if it is not going; if you do, that’s when your headaches will begin. If you can’t get the last NiTi to the apex, you can still fill the canal with the medium gutta percha point from Mailler/Dentsply. If you can get to the apex, then fill it with the # 30 gutta percha point from Diadent.
The Rotary NiTi Technique
I haven’t used the rotary NiTi system for years now, so please correct me wherever I’m wrong. I think that you still have to get a # 20 or # 25 size file to the apex before using the rotary NiTi. Am I right? If this is the case, then follow the steps above to get to size 25. If you don’t want to use the SafeSiders reamer, then my suggestion is to use any other type of reamer instead of a K-file. The reason for using a reamer over a K-file is that there is less binding with a reamer, so the instrument will negotiate the canal more easily. The SafeSiders reamer has a side shaved flat, which reduces the amount of binding significantly, so that it can negotiate the canal better than a regular reamer. If you have not tried the SafeSiders reamer in cases like this, you might want to try it. If you don’t want to, then that is OK, too. Use what you are comfortable with.
Instead of going into the rotary NiTi from this point, I would suggest that you go down with the Gates and Peeso as I have described above. This will reduce the amount of work and stress on your NiTi instruments. By the time you go in with the rotary NiTi, most of your work will already have been done coronally. All you have is the apical one-third to work on. The stress now is only on the apical one-third of your rotary NiTi and not on the entire length. This reduction in the stressed area will reduce the torsional stress at the curve, which in turn will reduce the chance of separation.
I hope this explanation is beneficial to you the next time you plan to tackle a curved root.
January - March 2008
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FIGURE 1: Tooth # 3 with a sharp curve in the MB root.
FIGURE 2: The MB root was shaped with minimal or no distortion.
FIGURE 3: Showing tooth #15 with a sharp MB root curve.
FIGURE 4: The extreme curve was shaped with no distortion.
FIGURE 5: Showing tooth #17 with two extremely curved roots.
FIGURE 6: The curve can be seen with the reamers in place.
FIGURE 7: The master cone with sealer in place.
FIGURE 8: The final film shows minimal distortion even for extremely curved roots.
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