Recently, at a hands-on course, a participant asked me when he could simply stop trying to negotiate a calcified canal and fill the given system to the level achieved, i.e., when is trying enough, in fact, enough? This is an excellent clinical question, and one without a simple answer.
Calcification occurs in a coronal to apical direction. As such, calcification is worst in the coronal third of roots. As one progresses apically, canals become more easily negotiable. The clinical implication is that it should become easier to negotiate canals with the apical progression of hand files. Inherent in the answer to the question are several methods without which achievement of complete canal negotiation would be difficult or even impossible. Let’s take a look at those methods.
1) The clinician must use a rubber dam. Combined with a rubber dam, a surgical microscope for ideal visualization and lighting would give the greatest overall visual command over the canal.
2) The clinician must have, in such a case, an optimal supply of No. 6-8 K files with which to attempt negotiation. If, after a given insertion, the K file comes out of the canal bent or deformed, it must be discarded and another new file used. Sharp new files are essential for breaking through such calcifications. These files ideally will be precurved with EndoBender pliers (SybronEndo, Orange, Calif.). It is possible they can be curved by hand, or less optimally, with cotton pliers. Precurving them will allow the file to more easily follow natural canal curvatures that may be present, as opposed to trying to passively place a straight instrument into what is always a curved canal space.
3) The clinician must be careful to always have an adequate supply of irrigant in the chamber as a reservoir. With each insertion of the small K files, irrigant is being introduced into the canal space. With each removal of the file, the space it once occupied becomes filled with the irrigant present in the chamber reservoir. For a calcified tooth, the optimal irrigant would be a small quantity of 5.25 percent sodium hypochlorite since it dissolves pulpal tissue, is antibacterial, and is clear (and hence can be seen as an aid in canal location). Especially under a surgical microscope, it is easy to visualize the canal through the sodium hypochlorite. In addition, where it is difficult to locate the canal, the necrotic tissue will bubble (dissolve) in the sodium hypochlorite. This functions as an aid in canal location. An alternative irrigant would be a liquid EDTA solution like SmearClear (SybronEndo). A comprehensive discussion of the relative merits of two irrigants will be discussed in a future column.
4) Given the above strategies for approaching such a calcified tooth, it is vital that the clinician not rush down the canal and that files be inserted passively. Literally, in a significant calcification, it may be necessary to advance the file only 1 mm at a time, followed by irrigation and placement of another file of the same size - usually a No. 6 in severely calcified cases. It is vitally important that the clinician does not advance debris apically beyond the level of the file tip, especially in a calcified or constricted canal of the type discussed here. It is easy to push such debris into the narrow lumen of the canal, and create a blockage of such magnitude that future negotiation may not be possible. Said in different terms, a difficult canal can be made impossible if an impassable blockage of debris is created and/or a ledge develops. Both these entities are situations that could have been avoided, rather than obstacles that were imposed upon the clinician and, thus, were out of the clinician’s control.
To summarize, if the canal is not negotiable after all of the above strategies are presented, then referral is an option. In many such cases, unless impractical for logistical reasons, referral is generally the best option. Given that all the best practices are undertaken, and no advancement can be made over the given level that the canal is instrumented, there may be no other option than to fill the canal at the given level. Fortunately, this is not often the case. The vast majority of severely calcified canals can be instrumented ideally and appropriately if managed from the start in the manner I have described.
As always, I welcome your questions and feedback.
Dr. Richard Mounce is in private endodontic practice in Portland, Ore. Dr. Mounce is the author of a comprehensive DVD on cleansing, shaping, and packing the root canal system for the general practitioner. The material also is available as audio CDs and a Web cast pay-per-view. He lectures worldwide and is a widely published author. For more information, contact Dr. Mounce via e-mail at comfort@MounceEndo.com. Visit his Web site at www.MounceEndo.com.