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Case of the Month

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September 2003 An Alternate Warm GP Filling Technique

September's Case of the Month was referred by a General Dentist who had previously accessed a maxillary premolar tooth but was having trouble negotiating his instruments to the Working Length. Rather than attempt to complete the case himself, he properly referred the case to a specialist because he detected something unusual about the canal system anatomy. While attempting to place his instruments to the radiographic terminus, he found that they were stopping quite short and he was unable to negotiate them further. This is the film that was sent with the referral (Fig. 1):

Fig. 1

As with every case that I do ( and especially those that have been started already!) I took my own preoperative images, one straight on and one with mesial shift.(Fig .2 & 3) The first thing that I noticed in this case was the relative ASYMMETRY of the lesion and that fact that the most radiolucent area was not at the root end. This is a big neon sign for "Lateral and/or Accessory Canal"!

Fig. 2

Fig. 3

Upon entering the canal system, my .08 and .10 hand instruments seemed to be going all over the place. The most frequent reproducible path seemed to be when I placed a very sharp bend on the file and then slid it toward the mesial. It appeared to exit quite short of the working length ( as measured to the root apex on a film) and at almost a 90 degree angle to the axis of the tooth. Whenever I deviated from this path, the instruments would stop short , bend or crumple. I just couldn't get them to the apex of the root, where I thought the exit of the canals should be. (Fig. 4)

Fig. 4

After repeated attempts, I decided that - rather than perforate the case - I would let the irrigation do the best job it could. The Canals were irrigated repeatedly with NaOCL 5%, 17% EDTA. Ultrasonic activation and heat were used to try to increase the effectiveness of the NaOCL and EDTA. I then dried the canals with 95% alcohol and my Stropko irrigator. At that point I was ready to fill the canals.

The problem was that traditional cone fitting techniques would probably be less than optimal. The cones would continue to crumple and bend and it would be impossible to get a proper cone fit. Instead of using a solid gutta percha cone technique, I used the System S - something I have been using almost exclusively for almost one year. An injectable Warm GP technique. ( A brief description of John Stropko's System S technique is posed at the bottom of the page.)

Fig. 5

Fig. .5 shows the results of the initial pack. There appeared to be three canals, with the lateral portal being the largest in diameter. ( It is possible that this occurred because I had worked it with some files, but the presence of the radiolucency on this area suggested that it may have been the MAIN portal of exit for the necrotic canal contents.)

Fig. 6

Fig. 6 represents the final result with the three canals clearly visible. I would have like to get to the terminus with the other two canals but under the circumstances (prior access and attempted instrumentation, blocked canals, complex anatomy) I thought the result acceptable. Although there is overextension of the filling material in the "mesial" canal, I was pleased that I could get a reasonably good reproduction of all three canals. ( The distal proximal box of the amalgam fell out immediately before temporary closure.)

Fig. 7
6 Month Post Op Recall Film.
Periapical healing despite the excess

Fig. 8
NEW - Sept. '04 -
1 YearMonth Post Op Recall Film.

 

The System S Technique
In October of 2002 I attended Dr. John Stropko's clinic and was shown how he does his "System S" (aka "Squirt") technique. John told me that he hasn't fit a gutta percha cone in over a decade and I was impressed with the great reproduction of canal system anatomy and apical control that he obtained when using this technique. It is a "pure" Obtura GP gun technique that uses Regular Set Schwed Gutta Percha pellets instead of the usual "low temperature" gutta percha formulation. ( John says this is VERY important !!) He also uses minimal sealer and takes great care in ensuring that the canal walls are dry prior to obturation. In this technique the sealer acts as lubricant for the Gutta Percha. The key to good apical control is proper canal shape and canal preparation. Once the GP is injected, a Dovgan or Schilder plugger is inserted into the mass and held there for 5 seconds to prevent shrinkage. The remaining gutta percha is "folded over" itself in a "wadding" technique that completes the obturation.
NOTE: This is NOT a technique for those who are afraid of small amounts of gutta percha in the periapex. While the aim is NOT to have GP in the periapex, the hydraulics that are generated by this technique can cause this to happen. These lesions heal without a problem but there are some clinicians (many Europeans for example) who get very upset at the thought of ANY material ( sealer or GP) extruded out of any portal of exit.

For further information about System S or taking courses with Dr. Stropko, check out John's web site: Endodontic Seminars Highly Recommended.

Conclusion
Canal anatomy is complex. Using cold gutta percha techniques that do not accommodate this anatomy can result in difficulties in obtaining proper obturation. The use of warm gutta percha techniques such as the System S provides a "non-GP Cone Fit" method that can compensate in cases such as this where prior instrumentation makes access to canal spaces less than ideal. The main portal of exit is frequently not at the physical root apex and it is important to recognize this prior to initiating treatment procedures.