Data Supported Critical Thinking Is the Best Form of Marketing

I have been writing about the advantages of 30o oscillating reamers powered by a 30o oscillating handpiece over the use of rotary NiTi for a number of years. For many of those years my critic?has challenged the validity of what I talk about, questioning any evidence I offer to support the claims made for their superiority. Along with those challenges which are completely proper, he emphasizes the fact that as a creator of this method of instrumentation, I derive profit and, consequently, anything I say positive about it or anything I say negative about rotary NiTi is illegitimate. That type of condemnation is not proper.?

Whether or not one derives profit is certainly grounds for anyone to be skeptical, but is not grounds for automatic dismissal. As in any debate where the goal is seeking greater insights, data is presented from all sides and those evaluating the data will reach their own conclusions. Whether or not someone has a commercial interest in what is being talked about is something that should be noted, but in no way has a bearing on the process of providing data or in the judgment of that data. The information provided by opposing sides is all that matters and it is in the weighing of that data by the audience many of whom may be actively participating that defines the process of critical thinking. It is critical thinking above all else that will determine how well we use the data provided.?

So, as we progress within this post, I believe that commercial interests are irrelevant if we are truly attempting to practice critical thinking. Those who want to emphasize commercial interests are bringing up issues that have an emotional appeal, but are not focused on data. So, lets look at some data regarding endodontic instrumentation, starting with the issue of instrument separation. This particular problem has always existed.?

Way before the introduction of rotary NiTi anyone doing endodontic instrumentation knew that one could separate an instrument in a canal by locking the tip apically while continuing to manually rotate coronally. As long as the manual use of K-files was the dominant form of instrumentation, instrument separation, never became an issue directly tied to a technique simply because the motion of the instruments were generally confined to short wristwatch arcs that minimized the chances of the instrument locking apically while being excessively rotated. In curved canals, the short arc of motion also prevented cyclic fatigue. Sure there are times dentists rotated these instruments excessively within the canals, but most dentists knowing the vulnerability of stainless steel K-files to separation when encountering excess torsional stress and/or cyclic fatigue and not wanting to introduce distortions, limited any full rotations to canals that essentially had straight configurations.?

It was only when rotary instrumentation became available that instrument separation was tied directly tied to a technique. Despite having a light hand and a slow progressive motion directed apically instrument separation, often undetected until the instrument was removed from the canal, became an issue compelling dentists to take precautionary steps to actively avoid such incidences. One of these precautionary steps, staying centered within the canals, resulted in a large body of research that documented?inadequate debridement of oval canal spaces and thin isthmuses. These issues, instrument separation and the resulting inadequate debridement of increasingly complex pulpal anatomy to avoid such separations were not and are not trivial problems.

That they are not trivial problems is most notable by the steps the major manufacturers of rotary systems are taking to overcome these shortcomings including the development of improved NiTi metallurgy making the instruments more resistant to torsional stresses and cyclic fatigue. This improvement in metallurgy has reduced without eliminating instrument separation?still requiring the precaution of staying centered that compromises debridement. Rotary advocates state that while centered shaping leaves debris in oval canals, the space created by centered shaping is adequate for the introduction of sufficient irrigants to render the canals three-dimensionally cleansed, that the irrigants need not be driven into intimate contact with the canal walls for them to be effective. Many studies contradict that viewpoint demonstrating large quantities of residual pulp tissue and bacteria remaining in the extensions of oval canals and thin isthmuses despite the constant presence of the irrigants. These studies, mostly?micro-CT videos, provide irrefutable evidence of the inadequacy of rotary NiTi in rendering complex anatomy properly cleansed.?

This particular problem has led to laser and acoustic powered irrigation systems that are far more aggressive in removing pulp tissue from complex pulpal anatomy and may, indeed, compensate for rotary’s shortcomings, at the cost of another highly expensive system. From a rotary advocate’s perspective, these more sophisticated irrigation systems are the answer to the genuine problem of inadequate centered debridement, that taken together they form a combined system that renders the canals more than adequately cleansed.?

That still leaves the problem of instrument separation, but given these powered irrigation systems, instrument separation can now be addressed most effectively by simply making far more conservative canal preparations. Thinner NiTi rotary instruments are far less vulnerable to the cyclic fatigue the instruments encounter when negotiating curved canals. The canal preparations take fewer instruments reducing the cost of armamentarium and the procedures require less time resulting in greater productivity and making their usage more appealing. The contention is that conservative preparations followed by laser or acoustic activated irrigation is the answer to the limitations imposed by centered instrumentation. These are quite expensive systems. There is no guarantee that any dentist adopting more conservative preparations is going to employ one of these more powerful irrigation systems. And anyone using these systems are well aware of their limitations.

As part of an ongoing discussion, the conclusion that laser or acoustic powered irrigation systems is the addendum that makes rotary the technique of choice is open to debate if other forms of instrumentation are considered. My alternative suggestion is the oscillation of relieved stainless steel twisted reamers?powered by a 30o handpiece at a frequency of 3000-4000 cycles per minute, a method of instrumentation that eliminates instrument separation. Once, separation is eliminated, the dentist is free to apply these instruments against all the walls of canals that are flooded with irrigants.?

Unlike a rotary system that requires a separate irrigation process, the high frequency of the 30o oscillating reamers in intimate contact with all the canal walls in canals flooded with irrigants is simultaneously physically and chemically removing the pulp tissue and bacteria from the canal walls in what is singularly called instrumentation. Now this last statement has instigated the ire of one particular critic who states that these claims are biased and false and are not to be believed because the motivation behind the claims is profit. To me, the most convincing proof I can offer is the obvious three-dimensional cleansing of a 3D printed mandibular molar where the mb and ml canals as well as the thin isthmus common to both canals are totally cleansed of simulated pulpal debris. Physically the 30o oscillating reamers were able to render the entire pulpal configuration of the mesial root of a 3D printed molar completely free of debris, something easily observed given the transparency of the material?from which the teeth are made.?

But, what about histologic studies? Debridement is a quantitative procedure not a qualitative one. We want to know if the tissue and bacteria are gone, not what type of tissue or bacteria are remaining. In a sense it is a gross appraisal of the mechanics involved. In that regard, the three-dimensional debridement of the mesial root of the 3D printed mandibular molar is ample proof of the effectiveness of this alternative method of instrumentation. However, I also supplied cross sections of extracted teeth instrumented and obdurated that failed to display any residual pulp tissue or bacteria after being instrumented with the oscillating reamers. In addition, there was a related study done by a group in France, that compared the cleansing potential of three rotary systems compared to the 30o oscillating stainless steel reamers. The 30o oscillating reamers was the only system that removed the smear layer and opened the dentinal tubules along the entire length of the canals, a not unexpected finding given prior research that notes rotary’s tendency to induce a smear layer in the process of cleansing the canals.

The critic’s response was predictable. No acceptance of these three data points as proof of anything. Indeed, in response to this data, there is an absence of recognition of rotary’s vulnerability to separation, that centered instrumenting leaves tissue and bacteria in the extensions of oval canals and thin isthmuses. No recognition that the entire mesial pulpal configuration has been well-cleansed. What there was recognition and repeated commentary on was the small amount of debris that was extruded apically, that this extrusion is proof that the system should be avoided. What is not recognized and certainly not appreciated was the fact that the entire canal space including the isthmus common to both canals was completely debrided.?

If we just concentrate on the subject of apically extruded debris, multiple research studies associate the greatest amount of apically extruded debris with the traditional use of K-files, something that makes sense given the up and down motion of an instrument designed with predominantly horizontal flutes. It is not difficult to imagine any debris present in the canal being?pushed apically by the plunger effect of such a designed instrument as it is inserted into the canal. Most dentists know that K-files have a tendency to cause blockages in curved canals with loss of length, a direct result of impacting debris apically while at other times simply driving it over the apex.?

The critic counters that if used with the balanced force technique, apically extruded debris is far less and he is right. However, the balanced force technique is manually applied, is hand fatiguing and takes a long time. Consequently, despite this desirable property the balanced force technique is not widely utilized. So, that leaves us with assessing the amount of debris extruded by other systems. Here the research does not give us a clear-cut answer. All engine-driven systems produce some degree of apical extrusion. The critic notes that systems that employ an up and down stroke are likely to produce more apically extruded debris. From all my observations I know of no rotary or oscillating system that does not employ up and down strokes for no other reason than to deliver the dentin shaved from the canal walls coronally where it is then removed.

Yet, he insists, that rotary is superior in that department. From my perspective I think if there are any differences between the two they are marginal. What is not marginal is the fact that the oscillating reamers referencing the instrumentation of the mesial pulpal configuration of the 3D printed mandibular molar cleansed the canal in three-dimensions while rotary instruments need at best a separate highly expensive irrigation system to adequately debride oval canals and thin isthmuses. So what is established presently is that the downside of apically extruded debris cannot be assigned to any one system and what perhaps may be more important and further exercised my critic is a study that clearly demonstrated that apically extruded debris in and of itself does not affect endodontic outcomes. He derided this study because it was limited to bone healing in the femur of rats, all of which healed despite increasing amounts of infected debris placed within the prepared sites.?

He states a study to be valid must include the debris that is extruded directly from teeth. That would make sense if the study?were about the overall impact of teeth on the success rate of an instrumentation procedure. However, the object of the study was restricted to the impact of debris on success rates. A study including teeth would have to account for any bacteria and pulp tissue remaining in the canal that deprives the investigators of the ability to have a single variable preventing them from reaching a conclusion on the impact of debris alone.

In summary, despite his repeated claims that what I say has no value because I derive profit from a product we initially designed for ourselves to overcome the shortcoming of what was and is the the dominant system, some form of rotary NiTi endodontics, I reject his opinion based on the discipline I try to employ in making every statement I make be it positive or negative?supported by research and clinical experience. HIs ultimate argument abandons any pretense of critical thinking when he states that rotary must be the best available system because it is the most popular. That popularity came about because of a broad spectrum of marketing by companies seeking a profit, the very concept he says nullifies whatever I say.

Regards, Barry