Is My Critic Unbiased?

Why does a critic continue to denigrate a technique that has several obvious advantages over rotary NiTi as well as denigrate me for bringing it to the attention of dentists? Reasonable conclusions are that he is an advocate of rotary NiTi for a host of reasons. Is he just being an unbiased honorable academic who believes strongly that the advantages of rotary outweigh the negatives? Does he lecture for rotary companies? Nothing bad about that in itself, but it could reasonably be construed that such conditions lead to a state of personal bias. Does he run a program where he works in close cooperation with the manufacturers of rotary instruments that support his programs? Nothing wrong there either if they do, but that too leads to the reasonable conclusion that it could result in personal bias. He has accused me in the past of talking about the endodontic products we developed for my own personal profit. That is true, but what he does not pay any respect to is the fact that I am still a full-time practicing endodontist for over 50 years and have developed products with the intent of overcoming the weaknesses of instruments that the major manufacturers introduced that I used. Examples of improved product design include the split-shanked Flexi-Post that gave the dentist the means to place a highly retentive dowel that minimized the insertional stresses to the tooth as well as distributed the functional stresses more evenly, the SafeSider stainless steel twisted reamers that have a flat incorporated along their working length and mainly used in a 30o reciprocating handpiece to negotiate even highly curved canals and thin isthmuses without any danger of separation, with far less resistance along the length, the almost complete elimination of hand fatigue and improved three-dimensional debridement.

?The incentive for these innovations was essentially for my own practice so I could perform more thorough instrumentation procedures with less fear of inducing an iatrogenic event. I was also aware through the extensive teaching I do that the concerns I have were also the concerns of most dentists I encountered. So I had the temerity to think that what was good for me might also be good for others.??Was there an economic opportunity there? For sure, but the main motivation was to develop products that made my own life easier and if they did to tell others about them. I recommend only what I use in my endodontic practice.

In the case of the 30o oscillating SafeSiders, it turns out that there is a cascading of advantages that derive from the basic fact that stainless steel relieved twisted reamers are confined to short arcs of motion at high frequencies. Once convinced that the instruments are virtually invulnerable to breakage, they can be used even in their thinnest sizes aggressively against all canal walls in a form of internal routing to cleanse canals in three-dimensions. As proof of that action, I have shown videos of the SafeSiders in the oscillating handpiece cleansing highly oval spaces as well as thin isthmuses, configurations that rotary would dare not do lest they increase the chances of separation. I have also posted a number of cross-sections of highly oval canals that show the complete debridement of these spaces. In contrast, the dental literature has clearly established the deficiency of rotary in cleansing oval canals leaving as much as 50% of the canal walls untouched.?

My critic has pointed out that the same video that shows three-dimensional cleansing also shows the extrusion of small amounts of dentinal debris apically, an event that in his opinion negates any of the positives this form of instrumentation brings to the table. In response, I note the conclusion of all research articles that conclude that no instrumentation technique devised to date prevents apical extrusion of debris and irrigant. His response continues to be one that pays no attention to the obvious advantages of 30o oscillation with the SafeSiders in terms of virtually complete resistance to separation as well as the observable fact that three-dimensional cleansing in highly oval spaces have been accomplished and repeatedly refers to the apical extrusion as if it is unique to this system.?

He claims the extrusion is a result of the up-and-down motion of the instruments ignoring the fact that every engine-driven system used today employs an up and down motion. What he does not say or possibly realize is that the greatest extrusion produced in the research studies result from the manual use of K-files in the traditional up and down motion, a logical result given the highly horizontally oriented flutes along length. The up and down manual stroke of the instruments applied against all the canal walls shave dentin away on the pull stroke and tend to impact debris on the push stroke when reentering the canal. The SafeSiders are reamers not files with a flute orientation that is predominantly vertical. The pull stroke is used to bring the debris captured in the depths of the flutes coronally not from the pull stroke, but from the short horizontal arcs of motion generated by the 30o oscillating handpiece. When the instrument is reintroduced into the canal the predominantly vertical flutes tend to bypass most of the debris that may still be present in the canal reducing the amount extruded apically. The flat incorporated along length further reduces the potential plunger effect compared to that of the traditional K-file.

So yes, some debris is extruded, but it is reduced because the plunger effect is not present as it is with K-files. The SafeSiders’ vertically oriented flutes along with the relieved flat along length combined with the short high-frequency arcs of motion mitigate the amount of debris extruded compared to the traditional manual use of??K-file. It should also be stated that confined to short arcs of motion with apical pressure applied the instruments are cleaving off small amounts of dentin per cycle in a fashion that is similar to the balanced force technique that has been shown in the literature to minimize the amount of debris extruded apically. The traditional balanced force technique is limited to the manual use of K-file type of instruments and is both time-consuming and hand-fatiguing, two problems that are eliminated with the use of the 30o oscillating handpiece.

These explanations have no impact on my critic’s response saying simply debris exists as if it is the only system that produces such results. No admittance that extruded debris is common to all instrumentation systems, no recognition of the favorable mechanical advantages including non-distorted shaping that derive from 30o oscillation of relieved stainless steel twisted reamers, but commentary on my personal character always a part of his criticism is not the basis of an unbiased appraisal of what I discuss. I suppose he will go on in this vein. Nothing to date has changed his approach. In the meantime, I will be posting many more cases that I and my colleague Dr. Kase have performed using this technique and it is for others to decide if they see any advantages to this approach. I will say that every time I give a course emphasizing this approach to dentists who are already using some form of rotary, the response is always highly positive. Maybe we are all wrong and my critic has some special talent for seeing the truth, but I think he is critical for far more mundane reasons.

Regards, Barry