Insights Regarding Endodontic Techniques

Our endodontic goals are to provide dentists (including specialists) the opportunity to expose themselves to techniques that overcome the shortcomings of rotary NiTi while improving the results compromised by rotary NiTi’s vulnerabilities.

Instrument separation: This issue has never been completely resolved in the world of rotary NiTi. Improved manufacturing processes have made newer versions of rotary NiTi instruments less likely to separate without totally eliminating the possibilities. The latest research articles in 2022 still note instrument separation a continuing problem, stemming from exposure to unpredictable amounts of torsional stress and cyclic fatigue in the instrumentation of increasingly complex pulpal anatomy. To moderate the negative impact of this to date unresolved problem, advocates of rotary NiTi state that all instrumentation techniques result in some degree of instrument separation. This being the case, it behooves the dentist to use rotary NiTi because the engine driven rotation of highly flexible instruments will prepare the canals with less hand fatigue than their manual counterpart while inducing a smaller degree of canal distortions.

One of our main goals is to give the dentists the opportunity to see that the totally mechanized?instrumentation techniques we advocate result in the virtual complete elimination of separations, that the dentists implementing these techniques cannot separate an instrument even if they wanted to and that mechanization from the start of the instrumentation process completely eliminates hand fatigue while significantly speeding up the instrumentation process. So what is the magic that provides instrumentation in the most complex of pulpal anatomies while completely avoiding separations?

There are two simple components that comprise this system. One, the instruments are used in a 30o oscillating handpiece that limits the arc of motion to 1/12 of a full rotation. With such a constrained arc of motion the torsional stresses and cyclic fatigue that can occur even in highly curved canals is insufficient to overcome the elasticity of the metal comprising the makeup of the instruments used. That brings us to the second component. The instruments used in the 30o oscillating handpiece are designed as stainless steel relieved twisted reamers. The predominantly vertical flute orientation of the reamers encounters significantly less resistance as they negotiate the length of the canals compared to the traditional use of K-files, instruments with twice the number of flutes along a similar working length of 16 mms. The instruments incorporate a flat along their working length that makes them more flexible and less resistance when engaging the canal walls. Of great significance is the fact that the flutes result from twisting the stainless steel wire rather than grinding the flutes in, a process that also produces defects that can coalesce and propagate into breakages under function. Combining the 30o oscillating handpiece with these stainless steel relieved twisted reamers eliminates separations, does away with hand fatigue from the very beginning and greatly accelerates the instrumentation process.?

Most importantly, by letting the dentist try these techniques using 3D transparent printed teeth, the dentist sees the entirely exposed process. Using instruments that are immune to breakage allows them to be used vigorously against all the canal walls, something that is routinely done with this technique, assuring an instrumentation process that adapts to the canal anatomy as it is rather than imposing a greater tapered round hole that does not touch the buccal and lingual extensions of oval canals and is incapable of penetrating thin isthmuses. Compare this process, one I call “internal routing” to the limited motion that rotary NiTi imposes as canal anatomy becomes more complex, namely the need to stay increasingly centered within the confines of the largest part of the pulp anatomy lest the increasing amounts of cyclic fatigue the instruments would be exposed to leads to a higher incidence of instrument separation. The primary need to keep the instruments intact led to inadequate instrumentation of canals that are increasingly oval in cross-section. This is not the case when employing the proper instruments in a handpiece that is limited to 30o arcs of motion even at a frequency of 3000-4000 cycles per minute.

The most recent strategies for those advocating rotary NiTi is to make excessively conservative preparations. We now see extremely thin preparations that often look no wider than a 20 or 25 just big enough to allow the introduction of a thin gutta percha point. The concept derives from an earlier time when silver points were used. In those earlier days creating a space for a thin silver point to the apex was generally considered a mark of success only to find out in follow-up studies that these preparations in oval canals often left untouched buccal and lingual canal walls. Thin rotary instruments particularly in canals of increasing curvature are unlikely to be aggressively applied buccally and lingually leaving even more debris than their greater tapered counterparts.

To importantly repeat, implementing relieved twisted stainless steel reamers in a 30o oscillating handpiece at high frequency gives the dentists the ability to fully debride the canals in three dimensions. From a point of adaptability to various pulpal configurations there is no comparison in the ability to thoroughly cleanse a wider range of these configurations when the method uses techniques that are virtually impossible to separate.

The fallback position for those advocating rotary NiTi is that this technique alone assures the least amount of distortion, and it is the minimization of distortion that is most important. There are several responses to this claim. First, if an instrument separates, at a minimum, distortions will occur in the attempt to remove the separated segment. If left alone, the segment now blocking access to the apex can be a cause of case failure, especially in non-vital cases. Attempts to negotiate around separated segments can lead to distortions including ledges, transportation, lateral stripping, and frank perforations. Our insights demonstrate the unique property of stainless steel relieved reamers when confined to short arcs of motion. Where a stainless steel instrument attempting to negotiate a curved canal can quickly lead to distortions when used with full rotations, confined to short 30o arcs of motion have been shown to conform to highly curved anatomy. Not only do the instruments remain intact, but they faithfully follow the canal anatomy. The reasoning behind this phenomenon was described by Dr. James Roane in a technique he termed, “balanced force”. It is based on the fact that when an instrument confined to a short arc of motion hits a canal wall, the wall is more resistant to deformation than the instrument causing the instrument to deflect into the path of least resistance, namely the existing canal space.

Using these techniques, dentists can learn first and foremost that the instruments will remain intact even when we tell them to try and separate the instrument while oscillating in the handpiece. They cannot do it. With that confidence under their belt, they now have the freedom to aggressively apply the instruments against all the canal walls resulting in three dimensional cleansing. They can readily tell that the canals in the transparent tooth models are cleansed not only mesio-distally, but bucco-lingually as well. Using three-dimensional models with curved roots they also see how the 30o oscillating action of these instruments provides undistorted shaping to the apex consistent with the balanced force technique. These are three insights that most dentists have never been aware of and not being aware of them led them to the compromised technique of rotary NiTi, a system that sped the instrumentation process up, reduced hand fatigue and was more adaptable to canal anatomy than that produced with the manual use of K-files, but does not compare to the safety of 30o oscillation using relieved twisted stainless steel reamers.

Rotary NiTi advocates cannot deny the readily apparent advantages of 30o oscillations when it comes to keeping the instruments intact, three-dimensional cleansing of oval canals and at least comparable abilities to shape canals without apparent distortions. One rotary advocate states that oscillation results in the extrusion of more debris apically. This may, indeed have been true when K-files were used manually with a push-pull stroke. Roane showed that K-files used with a short rotational reamer action did not produce the same amount of apical debris. The relieved stainless-steel reamers are designed to further reduce the amount of debris extruded when using the 30o oscillating handpiece. Numerous papers have been published stating that the balanced force technique, a method very similar to what is accomplished in the 30o oscillating handpiece with the relieved twisted reamers, produces the least amount of debris. That is not to say that some debris is not extruded. Dentin is removed from the canal walls with the rapid short horizontal strokes generated by the 30o handpiece. They do not direct the debris apically. Given the irrigants always present during the instrumentation process some apical extrusion is to be expected anytime an inward motion of the oscillating reamer is employed. To date there is no instrumentation protocol that doesn’t employ some instrument at some point in any technique with an inward motion even if it doesn’t touch the canal walls along length. The fact that the oscillating instruments are confined to 02 tapers reduces the hydrodynamic pressures apically. Rotary tends to use instruments of greater tapers and, consequently, has a greater potential to extrude debris when the in stroke is applied.

The above describes our endodontic insights and technique overviews, the technique accomplishments, and how it compares to the rotary systems that are dominant today. That dominance is based on a dearth of knowledge most dentists have about alternative means of accomplishing well-cleansed canals.?

For information regarding these insights please call Essential Dental Systems at 201-487-9090 or click here .

Regards, Barry?