Rationalizing Rotary NiTi’s Shortcomings

The advancements in NiTi metallurgy according to its advocates means instrumental separation is no longer an issue. If that is indeed the case the following would have occurred:

. Recent literature would no longer include studies on the rate of separations that range from 2% to 8%.

. The precautions needed to reduce the incidence of instrument separation would no longer apply.

. There would be no need to emphasize the use of retrieval systems.

. We would no longer see the reportage of separated instruments as posted on LinkedIn.

. No one would be attending our workshops that emphasize the complete invulnerability of the oscillating stainless steel relieved reamers to breakage.

The reality is that all these conditions still exist, that it is the dominant system because that is what is exclusively taught in the dental schools. The fact that the precaution of the centered positioning of rotary NiTi within oval canals and thin isthmuses canals is overwhelming documented to result in inadequate debridement is ignored as well as the separations that are inherent to rotary instruments negotiating more complex anatomy. When the facts of rotary NiTi’s use don’t fit the narrative of the two critics they simply dismiss these facts saying they no longer apply if they ever did. They may consider this approach effective, but it has no relationship to critical analysis and requires obliviousness to common sense empirical clinical experience.

Where rotary NiTi is vulnerable to breakage, 30º oscillating stainless steel relieved reamers are completely invulnerable to breakage. Where rotary NiTi must be used in the centered position to reduce the possibility of separation resulting in less than adequate debridement of oval canals, 30º oscillating reamers at a frequency of 3000-4000 cycles per minute are vigorously applied to all the canal walls resulting in superior debridement.

Rotary NiTi counts on its increased flexibility to negotiate curved canals without inducing distortions. The most flexible NiTi instruments are those that emphasize the martensitic (flexible) properties. The more martensitic the more vulnerable they are to torsional stresses. The more austenitic (stiffness) the less vulnerable to torsional stresses, but the more vulnerable to cyclic fatigue as they negotiate through curved canals. It is impossible to have maximum resistance to both torsional stresses and cyclic fatigue with the same rotating instrument.

30º oscillating stainless steel relieved reamers take a completely different tact in negotiating both curved and tight canals. Confined to an arc of motion that is 1/12 of a full rotation, the instruments never encounter sufficient stresses from the canal walls be it torsional stresses or cyclic fatigue to produce separations. The short arcs of motion produce a level of stress imposed on the canal walls that is less than their resistance, namely, the hardness of the dentin. As a result, when the 30º oscillating relieved reamers contact the canal walls, it is the reamers that give, deflecting into the path of least resistance, something easily observable in the many cases that I have posted on linkedin.

By limiting the arc of motion to 30º at high frequencies, the following beneficial actions occur:

. Separation is completely eliminated.

. Thorough three dimensional debridement is obtainable.

. Curved canals are negotiated without distortions.

. The potential to induce dentinal micro-cracks is greatly diminished compared to rotary NiTi

. The instruments invulnerable to separation are used multiple times with great cost savings.

. Hand fatigue is eliminated from start to finish. For the most part instrumentation is completely engine driven.

. The oscillating reamers unlike rotary NiTi effectively removes the smear layer providing for superior penetration of the bio ceramic sealers.

Certainly, rotary NiTi is a major advancement over the manual use of K-files. In that regard, if they were the only two choices dentists and endodontists had, it would be a denial of the progress that is attributable to rotary NiTi. However, with the advent of engine-driven 30º oscillating relieved stainless steel twisted reamers with all the advantages listed above, it is, imo, those adamant critics who refuse to see the inherent advantages of the stainless steel 30º oscillating system over the vulnerabilities of the rotary NiTi systems and are obstacles to the adoption of safer, more effective and more efficient methods of instrumentation. In short, to accuse me of being a Luddite is putting the shoe on the wrong foot.

Given the advantages stated above, it becomes entirely understandable why the major manufacturers of rotary NiTi systems take the marketing steps of attaining exclusive access to the student bodies through large corporate sponsorships that are so generous that the schools cannot resist. The immediate financial benefits to the schools are great enough for them to abandon any attempt to base instrument utilization on a critical review of the pros and cons of existing systems. Rather, access to. the student body is what the manufacturers purchase, a student body that becomes the commodity the schools are selling so the corporations can now have a future enhanced customer base.

Such distortions in education are inevitable when the operating conditions are created to primarily produce maximum profits for both the corporations and the schools that work hand-in-hand with them, an example of a corrupt marketplace that is dominated by those already most wealthy and powerful. To not think of the many aspects of education when a product or service is inevitably being offered is to be blind to what is happening. When looked at from this perspective, to not have critics attacking alternative forms of instrumentation as well as those espousing them, would be most surprising.

The more I understand the reality of the way our educational system works to promote the already powerful and wealthy, the more I rely on the sanctuary of endodontic workshops where the dentists completely familiar with what has already been taught, get an opportunity to try alternative methods that give them the options to eliminate the shortcomings of what they are presently using. From that experience, they can make their own independent decisions on what they are being introduced to. Call it a breath of fresh air that the established leaders have no desire for them to inhale.

Regards, Barry