An Analysis Of The Critic’s Comments Regarding The Shortcomings Of Rotary NiTi

The critic states that cycles to breakage have little meaning, that they don’t reflect clinical reality. On this particular issue he is correct. Generally, the studies regarding cyclic fatigue are constructed using tubes of different lengths and curvatures for the instruments to rotate through. What they don’t generally provide is the associated tight fit that the instruments would be encountering when instrumentation natural teeth. The combination of torsional stress and the stresses of cyclic fatigue negotiating around curves is generally not encountered in the models created for these studies allowing the instruments to go through a higher number of cycles before separation. So, he is right that the studies don’t reflect reality, but in a way that infers that rotary NiTi instrumentation is safer than it actually is.

He also references studies that state instrument separation is a rare event. How studies in a controlled environment, dental schools, where the instructors often take over the instrumentation when the students encounter complex situations can be considered a reflection of reality is a stretch. The most reasonable study I have read is one out of Saudi Arabia that linked the number of separations a dentist produces is directly related to the number of cases he/she is working on and that incidence is significantly higher that the figures the critic refers to in the studies he references.

From a strictly common sense point of view, any references the critic refers to regarding low breakage rates does not assuage the concerns dentists have when negotiating increasingly complex pulpal anatomy. Here, on linkedin, we have many examples of endodontists offering examples of dealing with instrument separation, from removal to negotiating around the separated segment. One does not get the sense that it is the rare event the critic implies in his selective references.

The simple truth is that rotation through increasingly curved canals subjects the instruments to greater amounts of cyclic fatigue that lead to a greater incidence of instrument separation. The manufacturers have introduced modifications of rotary NiTi to decrease separations including reciprocation that interrupts full rotations, more conservative preparations that expose the instruments to smaller amounts of torsional stress and cyclic fatigue and single usage. More conservative usage reduces separations at the expense of inadequate debridement particularly where oval canals, flat pulpal anatomy and isthmuses are present. Even if the critic was correct, where significant data says he isn’t, the lower separation rate would be the result of adopting a series of precautions that compromise debridement, the primary goal of instrumentation. In short, rotary endodontics has a built in dichotomy. The safety of the instruments are purchased at the cost of compromised cleansing.

When confronted with this dichotomy, the critic again references studies that conclude that despite these required precautions, the rotary systems produce superior results in debridement when compared to engine-driven 30o oscillations of relieved stainless steel reamers at a frequency of 3000-4000 cycles per minute that are vigorously applied to all the canal walls. There comes a point in the conclusions he references that they stretch the limits of common sense and we have to consider whether or not these results are unbiased. In my questioning them, he says I am a conspiracist who makes up stories to denigrate the inferior results reported for 30o oscillating stainless steel relieved reamers.

That particular position of his is undermined by the documentation that 80% of academic endodontists are the recipients of industrial payments as reported in JADA. If anything, JADA, a journal obviously supportive of the American Dental Association would be the last journal to report such information if it were not true and its obvious intent from this reportage is to bring to light the impact such payments have on the integrity of the research produced. When the critic states that the studies he references are independent, given the 80% of academic endodontists receiving corporate monies, the chances are 4 out of 5 that those producing the papers are by no means independent.

While the market for endodontic instruments is not as big as the oil or pharmaceutical industries, it is still a substantial market and calls for the same steps that the oil and pharmaceutical industries employ to support their respective markets. Buy the allegiance of researchers combining them with known opinion leaders to produce a body of “evidence” that supports the expanded use of carbon based fuels and an array of drugs that are far more expensive without improving the results of less expensive existing medications.

In the marketing of endodontics, the allegiance on different levels is purchased in a similar manner and under these circumstances the description of the research as independent is a delusion. One would think a report that 80% if academic endodontists receiving industrial payments would upset the apple cart. It is ironic that the steps needed to eliminate this form of influence could upset the apple cart so much that a good portion of the academic community doesn’t want to rock the boat. The schools and faculty already being rewarded by the corporations prefer to leave things the way they are allowing the corruption to continue and grow.

We often talk about how beneficial it would be to take the money out of politics to reduce the incentives for corruption. The same would be true in the corporate funding of research, particularly comparative research studies on commercially available products, but unlikely as it is to take the money out of politics it is equally unlikely to happen in the corporate funding of research and the researchers. Rather, under these circumstances, the best alternative we have is to be aware that this is the environment within which a large amount of education and research is produced. Pure research where no commercial product is being promoted is one thing, where we can all have assurances that it is unbiased. Research comparing commercially available products is where we should be most attuned to purchased distortions.

So, what am I ultimately suggesting? For one, don’t put a lot of value in comparative research studies. If one is looking for an improvement in their endodontic techniques, the best way to find it is via hands-on workshops. By taking workshops where the dentist can actually experience the performance of various methods, we have a vehicle where the course participants are the final judge of what they are using, making their own independent appraisals of an instrumentation system’s safety, effectiveness and efficiency.

Indeed, this is the approach we took in developing the 30o oscillating stainless steel relieved reamers. What we developed was first and foremost a system virtually immune to instrument separation. Having accomplished this first goal, we now had a system that could be vigorously applied to all the canal walls while the 3000-4000 cycles per minute frequency of the oscillating reamers activate the irrigants resulting in what we saw with our own eyes was superior debridement. The added advantage of 30o arcs of motion is that the instruments perform in a manner similar to the balanced force technique negotiating through curved canals without apparent distortions. While this particular point is challenged by the references the critic offers, anyone taking the workshops will notice the thorough three-dimensional debridement without any signs of canal distortion.

Personal observation trumps the conclusions of the studies the critic references in light of the 80% of academic endodontists receiving industrial payments. The participants pay for the workshops purchasing the opportunity to determine for themselves what works best. In today’s corrupted educational environment, a variety of workshops is the best solution available for accurate assessment of various endodontic instrumentation systems.

Regards, Barry