Regarding Rotary NiTi’s Unintended Consequences: No Problem!

While rotary NiTi endodontic instrumentation is presented as an advanced technology there is little note of its utility in three-dimensional cleansing with ample research studies describing its inadequacy in debriding the wider dimensions of oval canals as well as other asymmetric configuration. Let’s dwell on this fact. We know beyond doubt that except for some maxillary central and lateral incisors that conically shaped canals are the exceptions not the rule. This is borne out from cbct images and even more so in micro-ct scans. A further body of literature, recognizing the vulnerability of rotary instruments to separation strongly suggests using them in a centered position to minimize the impact of cyclic fatigue. A strong aversion to separation is likely more than enough incentive for dentists employing rotary NiTi to adhere to these precautions.

From a clinical point of view rotary’s inability to thoroughly debride non-conical pulpal configurations has been largely discounted with an emphasis on showing a beautiful often-curved white line from orifice to the apex as proof of superior instrumentation and obturation. While often effective, defining a thin minimally tapered white line in the mesio-distal plane as proof of effective three-dimensional instrumentation and obturation is simplistic. The deficiencies of rotary NiTi are not obscure. The literature abounds with studies documenting inadequate cleansing in the extensions of oval canals missing as much as 50% of the pulp tissue present. Another sector of rotary research correlates the conditions that lead to rotary separations with another branch of investigation observes the production of dentinal micro-cracks resulting from their usage.

?With the research clearly documenting rotary NiTi’s limitations, it is not illogical to think that dental schools having the responsibility to teach their students the most effective means to cleanse canals would consider that research as a barrier to overcome. That does not appear to be a standard that is being implemented. Rather the standard appears to be the implementation of a rotary system based on whatever manufacturer gives the school the best deal. At that point, the best the schools can do is to emphasize the precautions that need to be taken to keep the instruments intact. In so doing, it is unlikely that they will then state the problems that arise from taking these cautionary steps, namely excessive removal of tooth structure a result of crown-down preparations or the opposite, even less three-dimensional cleansing from more conservative centered preparations.

A productive academic exercise particularly in an environment where the promise and reality of rotary instrumentation reigns would be to clearly state the problems associated with rotary NiTi instrumentation and seek ways to overcome them. That would give the student body the opportunity to do some research and critical thinking regarding solutions. The problem with that approach is that the solutions are not hidden. If one goal is to prevent instrument separation, the answer is to use the instruments with short arcs of motion. The 30o oscillating handpiece has been around for several decades and produces an arc of motion that virtually prevents stainless steel twisted reamers from breaking. The research has been done. The results documented and are readily available for anyone to peruse. Yet, accepting that research contradicts the decision to teach rotary NiTi, a technique that also produces dentinal defects as reported in an abundance of studies.?

There is nothing esoteric about finding the research that discusses rotary’s downsides. That most dental schools do not delve into these issues is strong evidence that they prefer the financial arrangements that come along with the acceptance of a rotary system by one or another of the major manufacturers. Don’t blame the manufacturers. There is no surer way to influence future purchases of products than to have exclusivity in a student body that will then become consumers of dental products for the next 30 years. The students pay a high tuition with the incorrect understanding that they are to receive an unadulterated education based on science. The academic/industrial complex enriches the schools and the companies with the students unknowingly paying the price.?

Even as I write this post, I don’t want to believe the influence corporations have in influencing portions of a student’s education. Yet, I only have to refer back to the article in the November 2021 issue of JADA where it was noted that 80% of the endodontic academics accept industrial payments. This could not happen without the tacit permission of school administrators. There was a strong correlation between the amount of influence an endodontic academic has and the level of remuneration with the top 10% receiving 86% of the $4,200,000 paid out. On the one hand, dental administrations evidently permit the industrial payments to faculty and on the other hand, you have 80% of the faculty accepting such payments. Then separately, the administrations work with the dental companies to teach those systems that are most generously supported by the companies making their bid for student body exclusivity.

This is not muckraking. It is simply a fact, a much smaller example of the military/industrial complex that President Eisenhower warned us about 60 years ago. What a different world it might be without the distorting impact of major industrial interests, the influence they wield of which we know little and is only looming larger through their concentration of power stemming from mergers and acquisitions.?

I probably would never be writing posts such as this if I were not a small manufacturer of alternative approaches to endodontics as well as a full time practicing endodontist. Being both, and having developed alternative endodontic instrumentation techniques after first purchasing and using different rotary systems, I knew exactly what I wanted to avoid and looked for simpler methods to prevent separations, debride in three-dimensions with minimal loss of tooth??structure, prevent hand fatigue and generally add speed and efficiency to the procedures.?

Having a foot in practice and manufacturing gives me a perspective that lets me see the good and bad of consumerism. While profits are necessary to remain in business from my perspective it is education that matters and must be the foundation for any courses we give as well as any dialogue I have here on linkedin and elsewhere. To have any other mindset cannot work in the long run and would quickly be uncovered by the very audience that I attempt to communicate with.?

Regards, Barry