DEALING WITH ENDODONTIC PROBLEMS

[Anonymous]

PERFORATIONS

The main problems with perforations are (1) the angle of access is not in alignment with the angle of incidence; (2) bleeding; and (3) difficult to compact due to lack of a backstop (Figures 1a and 1b). Prior to MTA (DENTSPLY/Tulsa), time-tested materials such as Calcitite nonresorbable hydroxyapatite bone-grafting material (Calcitek) were used to create perforation barriers to seal against with good long-term results. MTA has further improved results. With the use of microcarriers to place the MTA and then trowel it into the perforation with microspatulas such as the West Nos. 1 and 2 and Nos. 3 and 4 (Sybron Endo-dontics), this material has led to excellent success by many clinicians

BLOCKS

What is the anatomy of a block? How are they formed?2 What does the dentist have to think and do in order to predictably “deblock?” When an instrument does not go to length due to a dense collagen or “dentin mud” block, the densest part of the block is the most incisal or coronal. The majority of the apical portion is more “lightly packed” (Figure 2a). The reason for this is found in how the block got there in the first place. It is often there because of lack of restraint by the clinician. First, he or she discovers the instrument just “won’t go.” The very next human reaction is to push. That does not solve it so we push harder. The clinician experiences more frustration and begins to push harder and harder, thinking that this forcing will enable him or her to thrust through the block back to home base.

A more effective technique is to do exactly the opposite of forcing and trying. If the clinician were to choose to be delicate, patient, and demonstrate extraordinary restraint, then deblocking is predictable and fun. We will always go deeper, although it may only be a micron! This enables the clinician to disturb the dense block and then easily navigate to the terminus again (Figures 2b and 2c). A No. 8 file is recommended.

Rules for Deblocking

(1) Remember, the path is still there.

(2) Shake your fingers “loose as a goose.”

(3) Whistle a merry tune.

(4) Irrigate thoroughly with sodium hypochlorite.

(5) Make believe you can do this.

(6) Forget the clock.

(7) Remember the game of restraint, and the promise to slide deeper is the reward.

(8) Use randomizations and not searching.

Now, these rules always work, unless they do not! Imagine you have faithfully followed these steps not 10 times, but say 30. When these blocks are so dense, they need a little more persuasion, or, shall we say, encouragement. A useful irrigant at this point is Chemet (Succimer, 150 mg).3 This “compounded strength EDTA” in combination with a No. 20 reamer (preferably carbon) will enable the clinician to “tunnel” through and down almost any dense collagen or dentin block and then successfully clean, shape, and develop obturation hydraulics that enable a 3-D seal and healing

LEDGes

Ledges are an endodontic clinician’s least favorite friend (Figures 3a and 3b). In addition, one of the fatal flaws of NiTi rotary is when a smooth glide path has not been created before the rotary shaping. Previous techniques required the clinician to precurve a small file or hedstrom, slip around the ledge, and circumferentially file to reduce the ledge sufficiently to allow the gutta-percha cone to go to length. Of course, the outline form was permanently imperfect, and to shape smoothly beyond the ledge was more luck than intention. Precurv-ing a ProTaper F1 (ProTaper, DENTSPLY/Tulsa), sliding past the ledge manually, and then rotating manually for 2 to 4 revolutions can achieve a more effective elimination of ledges (Figures 3c to 3e). These finishers are designed to cut at exactly any spot that prevents its exact shape from being carved

        

[Anonymous]

This in vitro study used computed tomography (CT) to compare the occurrence of canal transportation in the apical third of mesiobuccal canals in maxillary molars instrumented with 3 techniques. Sixty teeth were assigned to 3 groups (n = 20), and the root canals were instrumented as follows: Group 1, hand instrumentation with K-files; Group 2, K-files coupled to an oscillatory system powered by an electric engine; Group 3, ProTaper NiTi rotary system powered by an electric engine. To compare the canal transportation produced by the different techniques, preinstrumentation and postinstrumentation 3-dimensional CT images were obtained from root cross-sections of the region located 3 mm short of the apical foramen of each root canal. The CT scans were exported to Adobe Photoshop software, and the initial and final images were superimposed to detect the root canal wall differences between them. Canal transportation was measured by the distance between the prepared canal center and the anatomic canal center. The manual technique produced lesser canal transportation (0.10 mm) than the oscillatory and rotary techniques (0.37 and 0.22 mm, respectively); this difference was statistically significant (P = .021). All studied techniques produced canal transportation.

        

[Anonymous]

NEGOTIATING TO THE APEX in order to gain a working measurement is not always an easy task. I often hear from dentists that the canal is “blocked” or “calcified,” and they ask what they can do to get the 08 or 10 instrument down to the apex for a measurement. In some instances, the canals are blocked with calcium, but most of the time the canal makes a sharp turn that makes it impossible for a straight instrument to get around or past that bend in the root. The answer is always the same: pre-bend the endodontic instrument. A bent instrument will never get you into trouble. A straight instrument in a curved canal can lead to several iatrogenic problems.
If the instrument has a bend at the apical tip, the instrument circumscribes a circle at the tip when you rotate it. As you rotate the circle around the canal wall, it will eventually drop into the curved part of the canal. You will then be able to go to the apex of the canal. If the instrument is straight, it will circumscribe a point at the apical tip when you turn it to find the bend in the canal. The point will not find or fall into a curved canal. In fact, if you work the instrument enough it will make a ledge in the canal. Ledge formation is iatrogenic and makes instrumentation harder to do; consequently, completing the root canal procedure will take longer.
The best way to avoid creating a ledge in the canal and to find the curved canal itself is to place a 45-degree bend in the endodontic instrument. As you place the endodontic instrument into the canal and rotate, it will eventually fall into the canal
At that point, you can gently use a “wrist watch” motion to get to the apex. The 45-degree bend is easy to make with any “College pliers” or locking pliers. Just grab the apical end of the endodontic instrument with the pliers and bend the end to approximately 45 degrees. In a stainless steel instrument, the bend will remain when you release the instrument
The bend will not remain in a NiTi instrument. Because NiTi instruments are super-elastic, they do not hold a bend; instead they return to their original shape once released from the pliers.

        

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