Separating Myth From Reality in Evaluating Endodontic Products

?Rotary NiTi is often described as a paradigm breakthrough in endodontic treatment. This evaluation is based on its increased flexibility allowing it to better adapt to curved canals while also being more resistant to cyclic fatigue. What should be clearly understood is that the comparison between NiTi and stainless steel is based on its performance in rotation. Within the parameters of rotation be it continuous or interrupted (asymmetrical reciprocation) NiTi performs better. Under these conditions NiTi is more resistant to separation and it is far less likely to produce canal distortions. So as long as the only technique under consideration is rotary, NiTi instrumentation is the way to go.

Even being confined to rotary techniques would not necessarily subtract from rotary’s evaluation as a paradigm improvement if under function it performed safely consistently and was effective at cleansing all canal configurations well. It is in its performance that the evaluations of rotary accumulating over the years since its introduction in 1988 that ultimately throw into question its status as a paradigm breakthrough. Rotary is intimately associated with instrument separations. It has been shown to be ineffective at cleansing the buccal and lingual extensions of oval canals. It induces dentinal micro-cracks and is often used in a crown-down manner that sacrifices significant amounts of dentin weakening the tooth structurally and making it more susceptible to vertical fracture.

To keep the myth of rotary NiTi’s paradigm improvement intact requires either ignoring the research that details its adverse effects or relegating the adverse effects to nothing more than a minor inconvenience. Either way, the recognition that should be paid to flaws in the systems is minimized. That has the effect of perpetuating rotary NiTi’s paradigm status with the worse effect of discouraging insights into approaches that can overcome these negative consequences.

If you want to avoid instrument separations confine the motion to narrow arcs not exceeding 45o. Along with the avoidance of instrument separation, short arcs of motion allow stainless steel reamers both unrelieved and relieved to follow the canal anatomy to the apex without producing distortions. The fact that short arcs of motion allow 02 tapered stainless steel reamers to negotiate canals without distortion is not generally appreciated. What has been observed is the rotation of stainless steel instruments producing transportation of curved canals to the outer wall, something advocates of rotary NiTi use to accentuate NiTi’s greater adaptability. The differences between stainless steel and NiTi are real, but the negative differences become superfluous when stainless steel reamers are confined to short arcs of motion.

Short arcs of motion generated in a 30o oscillating handpiece follow canal anatomy extremely well as originally demonstrated by James Roane’s balanced force technique negating the claimed exclusivity of rotary NiTi being the only way to shape canals distortion-free. What is not appreciated, but is of primary importance is that short arcs of motion not only provide accurate negotiation of canals, but provide this ability with virtually no danger of separating the instruments. While rotary NiTi must confine itself to centered shaping, the widest portions of the canal, short arcs of motion give the dentist the freedom to aggressively apply these stainless steel reamers against all the canal walls removing a more or less uniform amount of dentin circumferentially and maintaining the original canal anatomy in larger form.

Rather than being a paradigm improvement as some claim rotary NITi to be, 30o oscillating reamers not only carry out the function of effective canal cleansing and shaping, but do it without the drawbacks of rotary NiTi. The oscillating motion employing the stainless steel reamers both unrelieved and relieved is mechanized via the use of a 30o oscillating handpiece that generates a frequency of 3000-4000 cycles per minute making it not only safe, but efficient in carrying out the tasks of cleansing and shaping with the added advantage of activating any of the irrigants that flood the canal anatomy.?

?Should we define 30o oscillation of stainless steel reamers both unrelieved and relieved as a paradigm improvement? In my opinion, no, but we should appreciate the convergence of pre-existing technology with minor refinements that can produce a huge clinical improvement. Stainless steel reamers have existed for years. For reasons I have discussed in detail in previous posts they function far better than K-files. I have also discussed the advantages of reduced resistance gained by incorporating a flat along their entire working length.?

The 30o oscillating handpiece has been around for years. Used in the past with K-files they encountered significant amounts of resistance as they negotiated canals and at times impacted dentinal debris apically causing a loss of length that could lead to canal distortions in attempts to regain that length. By combining the oscillating handpiece with the reamers both unrelieved and relieved from 15/02 onwards, we now have a system that rapidly widens the canals in three-dimensions, sonically activates the irrigants for greater effectiveness, minimizes damage to the canal walls and allows the instruments to be used safely several times before replacement. No major input of new technology with quantum leaps in cost entered into this approach.??

We don’t need myth making. What we need and have in linkedin is at least one forum providing a sounding board for new and alternative ideas that can reach more dentists and endodontists. Myth making in terms of consumerism is simply another vehicle to maintain the dominance of products, erasing if possible any faults associated with the product and emphasizing the ineptitude of anyone attempting to challenge its dominance. It is a challenge to see through the strategies corporations use to maintain that dominance. I like to write about the common sense observations we can make that hopefully lead us away from tribal thinking and increase our ability to think critically. Those skills improve us and can be applied in all situations including being critical of what I say as long as it is based on solid reasoning. Raising emotion an elemental part of myth making may make us more confortable, but it doesn’t make us more informed.

Regards, Barry