Re: Paper point technique

CONTINUING THE EVOLUTION OF OUR TECHNIQUE

What if there was a way to “titrate” working length for each individual canal or foramen? No more underfilling or overfilling unless desired. Such a method exists. It allows determination of the distance to the cavosurface of every unique canal in each root. This measurement can be performed to within tolerances of 0.25 mm, consistently, without radiographs. It allows us to “see” the cavosurface of the canal.

The beauty of this method is that once the distance to the cavosurface of the root is known, the MAFD at that length can be determined. Once length is determined (which means we have negotiated the canal to its terminus), the MAFD at that length can also be determined, then the two variables needed to successfully complete the endodontic equation are known. With this knowledge comes control of instrumentation and obturation that allows the doctor to determine where to terminate treatment. The results designed are the results produced. We can truly become masters of our domain.

This measurement technique is performed with paper points. In addition to extremely accurate and consistent length information, paper points can sometimes give three-dimensional information regarding the location and slope of the apical foramen.

This three-dimensional information can be extremely valuable in developing control over the most apical extent of the canal. There is no need to worry about overextension of gutta-percha. There is more concern that fitting the gutta-percha short of the ideal termination point will result in obturation that remains short of the ideal termination point. With good apical control the gutta- percha cone will not advance even under the pressure developed by vertical condensation forces.

When we are lacking length or minimal apical foramen diameter information we cannot attain the same degree of control. In these situations we need a little bit of luck to help us pull it off. Gifted clinicians can pull it off routinely, intuitively knowing and feeling the variables. But for those of us who might need to take a few practice swings before going on the golf course, or maybe even need a lesson now and then, it is nice to have all the information we could possibly need. Wouldn’t you like to know the exact yardage for your golf shot, the exact slope and speed of the green? Tiger Woods has a feel for it. Most others would like all the help they can get.

THE POINT

The concept behind paper points being used to provide accurate length information comes from the idea that when the contents of the root canal system are removed the canal should be dry. The extraradicular (or more accurately extracanalular) environment is living and hydrated. There is the PDL, granulation tissue, pus, blood, bone, or some other hydrated tissue containing fluid that exists beyond the cavosurface of the canal.

If a paper point is placed into a dried canal and removed short of the apical foramen, it should be retrieved dry (Figure 17). If a paper point is placed into a dried canal and taken past the cavosurface of the canal it will be retrieved with fluid (blood, pus, serous fluid, or mucus) on that portion of the point that extended through the cavosurface of the canal. Because of capillary action the wet portion will be extended some distance further along the point than the portion that was directly in contact with the fluid (Figure 18). The length of paper point affected by this capillary action is dependent on the viscosity of the fluid present beyond the canal and the absorbency of the paper point. We don’t need to know this information in order to get accurate length information from paper points.

The technique for paper point measurement can be simple. Into a dried, patent canal place a paper point. A trial paper point is placed 1/2 mm short of the EAL length. If the point comes out dry advance it until it picks up some fluid. Note the length of the point that is dry. Now, another point is taken just short of this length, removed and observed. For this example assume that the point comes out dry (Figure 19). Re-introduce and advance the point until the very tip of the point has the slightest bit of fluid on it (Figure 20). The point should not remain in contact long enough for any capillary action to have taken place. Record the maximum length that the point can be placed into the canal and remain dry as the length of the canal. This is the cavosurface of the canal

Now that an accurate canal length is known, the MAFD at this length can be determined. By taking K files to the paper point length without rotating them, but with apical pressure, a file that will not go long but will bind at or just short of paper point length will be found. This file represents the MAFD.

Of course there are some subtleties to the technique. In teaching this technique for the past few years I have also become aware of the common problems and misconceptions that doctors new to the technique have in common. In part 2 of this article I will address several of these issues and offer solutions.

CONCLUSION

This article will facilitate quality endodontic treatment by taking advantage of the developments that have taken place in the last decade. The paper point technique would not be a consistently reproducible technique without advances in instruments that have taken place, notably the introduction of greater taper files.