Tricks of the trade

July 1, 2004
Wisdom would dictate that it is better to learn the trade than to learn the tricks. That said, knowing a few methods — tricks — to get out of a problem can go a long way toward excellent clinical endodontic results, if used appropriately.

Richard Mounce, DDS

Wisdom would dictate that it is better to learn the trade than to learn the tricks. That said, knowing a few methods — tricks — to get out of a problem can go a long way toward excellent clinical endodontic results, if used appropriately. With this in mind, here are several helpful troubleshooting strategies for common problems.

1) What do I do for persistent, copious bleeding from a canal with no apparent explanation?
Obviously, the level from which the canal is bleeding and the possible presence of an iatrogenic event can impact the answer as does the quantity of bleeding. If you are relatively certain that no iatrogenic event has occurred, then fully instrument the canals to the radiographically determined true working length. If the bleeding persists, calcium hydroxide can be placed in the canal in the form of a dense slurry with pluggers - calcium hydroxide powder can be mixed with anesthetic, for example, and the tooth can be sealed for a few days to weeks. Usually, upon reentry, the bleeding will stop and the tooth obturated. While other valid methods exist, this is my preferred strategy of choice for this occurrence.

2) I could get down the canal easily, and then suddenly I can't. Why not?
It's possible that either a file has been separated in the canal, or some compacted material (pulp, denticle, dentinal shavings, a filling, a mass of dentin mud) has obstructed the canal. It is not always known to the operator that a file has separated, especially with tiny fragments of K files. A logical first step is to take a radiograph to determine if a file has separated or to look for other clues as to why the canal isn't patent. Even a tiny fragment of a small K file (less than a mm) is often enough to fully occlude a narrow canal. This is a strong argument against using K files twice, especially in the smaller sizes. If a file has separated, the patient should be referred to a specialist for its removal if it cannot be bypassed. Bypassing an obstruction in the absence of a separated file takes time and requires the use of a precurved K file (usually a 10 or smaller). The file is directed into the blockage and inserted in multiple orientations to slowly explore a route through the plug of debris. Irrigate frequently. Once you have broken through, use very short amplitude strokes (1-2 mm) repeatedly to enlarge the pathway for subsequently larger K files until the plug is easily and reproducibly negotiated. The EndoBender pliers by SybronEndo are an excellent tool to help create this bend in the apical 3-4 mm at the tip of a K file. While cotton pliers can be used to pre-curve the K files, the curvature created is not as predictable or efficient in locating a pathway through the blockage.

3) My apex locator skips around and does not always work the same way every time. What is wrong? From my empirical observation, electronic apex location, despite manufacturers' claims, is most accurate when there are no contents in the canal and the canal is dry. In addition, it is important to use the largest file possible when taking a reading and to keep the file off of any metal restorations. Clinically and empirically, the Elements Diagnostic Unit apex locator (SybronEndo, Orange, CA) has been the most consistently reliable machine I have ever used. Interestingly, using a paper point to confirm the true working length is a very accurate method to evaluate the accuracy of a given machine. In essence, after the canal is instrumented completely and dried, if the apex locator is reading accurately and the canal is patent, the clinician should be able to take a paper point of an appropriate size and taper to the true working length and get a reproducible bleeding or moisture point as a confirmation of accuracy to assure the clinician that they are at the minor constriction of the apical foramen.

Future editions of the Endo File will examine each of these individual subjects in more detail.

Dr. Richard Mounce is in private endodontic practice in Portland, Ore. He lectures worldwide and is a widely published author. Contact Dr. Mounce via email at linek [email protected]. Visit his Web site at

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