It's all about access
The principles of endodontics are to clean, shape, and fill the root canal system. We also can add the principle of doing a root canal where we restore the tooth and re-establish occlusion.
Dennis Brave, DDS
Kenneth Koch, DMD
The principles of endodontics are to clean, shape, and fill the root canal system. We also can add the principle of doing a root canal where we restore the tooth and re-establish occlusion. It is not particularly beneficial if we do a great root canal, yet destroy the tooth in the process. Too many patients show up with fractured teeth. It's true that some of them come from poor post design, but others are the result of removing too much tooth structure during the endodontic procedure. One of the nice things about a rotary technique — especially with a .06 taper — is that they actually are quite conservative in the coronal third of the canal. The conservation of tooth structure will help in the long term success of a case.
There are four keys to endodontics: diagnosis, access, instrumentation, and obturation. While diagnosis certainly is the most difficult, access is the key to successful clinical endodontics. Here comes a bold statement: With today's technology, once we have established proper access, the case is basically complete (unless the canal is calcified.) When proper access is created, NiTi rotary instrumentation predictably results in properly shaped canals that are neither transported nor ledged. Consequently, when you have proper cleaning and shaping (as with a continuously tapered .06 preparation), whatever obturation method you choose will work quickly and well. When we conduct our Real World Endo Institute courses, the participants generally complete numerous teeth. It's not unusual for some participants to finish as many as 15! How is this possible? Simple: Because we spend two hours on the first day creating straight-line access and finding calcified canals. Consequently, the participants prepare teeth that are properly accessed. The result is much easier instrumentation and obturation.
When accessing anterior teeth, we make initial access with a No. 2 round bur and then flare the walls of the access preparation for straight-line entry into the canal. Too often, we see access on anterior teeth that, if continued, would perforate through the buccal CEJ area. While we try to be as conservative as possible on anterior teeth, we still need to have sufficient access to complete the root canal. When the affected tooth is a premolar with two roots, we must make an access that incorporates both canals into the preparation. The walls of the access must be directed in such a fashion that access is straight line into the canal. If you have a case where you think there is a second canal, but you can't find it, it is often due to improper access. Sometimes, by extending the access either buccally or lingually, you can incorporate the missing orifice into the access preparation.
We recommend a slightly oval access on all premolars. If the tooth has two canals, two canals that merge into one, or one canal that bifurcates, then an oval access preparation is required. Therefore, with premolars, always use an oval shape preparation. One point we consistently stress at our seminars is that the key to instrumenting molars really is the access. Unfortunately, too many practitioners make only a small, round hole in the center of the crown. Consequently, they try and curve a K-file to get into the orifice and the canal. What usually happens from this improper access is that at approximately the 18 mm mark, or prior to the curvature, the instrument will not follow the curve. Rather, it will deflect to the side and ledge the canal. The absolute key to doing curved canals is to have proper straight-line access.
Always remember: An instrument curves once. If you need to curve the instrument to enter the orifice and it goes down into the canal 18 or 19 mm and needs to curve again, guess what? It will not curve! Instead, it will deflect to the side and you have now created a ledge. This is an adage that applies not only to stainless steel but to NiTi instruments as well.
Real World Endo tip: Endodontic residents always want to know "how to do the curves"— as if there is something magical in the apical 3-5 mm! Again, it's all about the access created in the coronal part of the canal. If you spend an extra five minutes in creating proper access, it will easily save you 20 minutes in completing the case.
Join Drs. Koch and Brave for their seminar, Real World Endo, in Scottsdale, Ariz. on November 8 and 9, 2002. Learn from experienced clinicians who actually have used these techniques on thousands of cases. Drs. Koch and Brave approach endodontics from a totally different perspective, that of the "Real World" clinician. It is not about them. It's about you, the participant, and learning how to do endodontics faster and more predictably. Drs. Koch and Brave will continue to give you exactly what their motto states, "Just the Facts, Nothing but the Facts." This is endodontics education at its best. For more information, see pages 192-193 or visit www.dentaleconomics.com.
Dr. Dennis Brave is a diplomate of the American Board of Endodontics and was the senior managing partner of a group specialty practice for 27 years.
Dr. Kenneth Koch is the founder and past director of the new program in postdoctoral endodontics at the Harvard School of Dental Medicine. Drs. Koch and Brave together are Real World Endo, an endodontic education company. They can be reached at (866) RWE-ENDO, or visit their Web site at RealWorldEndo.com.