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New additions to the NiTi rotary file market: What to bring in and what to leave out

L. Stephen Buchanan, DDS, FICD, FACD (DTI/Photo Endobuchanan)
L. Stephen Buchanan, USA

L. Stephen Buchanan, USA

Wed. 5 October 2011


Nickel titanium rotary shaping files fundamentally changed everything in endodontics; conceptually, procedurally and economically as well. NiTi rotary files made root canal therapy more accessible and kind of fun for dentists, and dental companies were loved for making files that cost four times more than SS hand files but delivered a ten times improvement.

Those seeds of success have grown into today’s endo market, where we have come to expect another new file on the market every six months. Granted, it’s a quality problem, but while some of these new instruments have significant improvements in tip and blade geometry or were made with improved metallurgical and forming processes, some have offered little advancement over existing technology. Their introductions were just business moves proposed to benefit a dental company instead of dentists and their patients.

So how do we sort through the list of new, new instruments and decide whether any of them truly offer clinical advantages commensurate with the high cost of purchasing new instrument inventories, new handpieces and the retraining needed to become competent in their use?

To my mind there are only a few reasons to change to a new rotary file system:

  • Improved safety and consistency of result.
  • Improved efficiency if the safety and outcomes imperatives have been met or exceeded.
  • Improved procedural simplicity and/or cost of providing endodontic services to patients.

In that order! Any new instrument delivering improved efficiency at the cost of safety and predictability of outcome is a fool’s choice. So if we are choosing for excellent outcome, we usually look at our failures and consider how we could eliminate those painful and expensive experiences from practice. However, deconstructing endodontic failures can be nearly impossible, so it is imperative for dentists to choose for the right reasons.

One of the greatest challenges to dentists making these decisions wisely is the difficulty of deconstructing endodontic failures — the prime example being failures due to apical damage caused by aggressive tip and flute geometries.

Dentists who use rotary files have all suffered instrument separation when difficult anatomy has been encountered and rotary files have been allowed to rotate for too long — and plink! This is why dentists are instinctively drawn to rotary files that cut effortlessly to length. If it gets to length and is held together, big worry No. 1 is done. Whew!

The “unknown worry,” the “elephant in the access cavity” that few are aware of and hardly anybody talks about, is the apical laceration that commonly occurs during rotary shaping procedures. The reason such a big problem is spoken of so little, is that when apical laceration during rotary shaping (alders) occurs, the only evidence of the disastrous shaping outcome is the inevitable overfill that follows — a result seldom attributed to its true etiology but most commonly identified as a cone fit or condensation failure.

When a given file design always cut to length, it is highly unlikely to exhibit fidelity to the original canal path in apically curved canals. Combining that fact with the fact that at least half of all canal curvatures are hidden in our conventional radiographic imaging, makes an incontrovertible case for safety above cutting efficiency if only one of these two attributes is designed into an instrument set.

That leaves us to consider new files introduced to solve mythical problems not proven to exist or to deliver efficiencies provided by already existing instruments.

The best example being the SAF (self adjusting file) brought to market and abandoned less than a year later. This cardiac-stent-like file, truly a beautiful design as its hyper-flexible, cross-laced struts are laser-cut out of NiTi tube stock, was hailed as a transformational file, and that it is.

What it isn’t, is an instrument that cuts dentin, but rather only sands it, thus creating no reproducible canal shape, thus catapulting us back to an era before system-based endodontics related obturation procedures to specific pre-defined shaping outcomes. Oh, and there was also the issue of needing to buy a proprietary handpiece/irrigation device and a $50 cost/instrument. So whose bottom line was in mind? Not yours.

Another example is the recently introduced reciprocating file. What problem does this solve for you? Do you need to spend money on a new handpiece and learn an entirely different technique for shaping canals that won’t improve your results, or your bottom line? And is the claim that you can cut a shape with one file entirely true, or even new for that matter?

Single-file shaping is not a new or unique claim, as GT and GTX Files have cut single-file shapes since 1996. And, as I know the ramifications of cutting to length with a single file, there is no file design on earth that can cut a single-file shape in all canals. Two to three files to cut shape in a nasty root? Sure, but nobody gets a single file to length in that one. The large roots with huge apical canal diameters? Two should do it, but nobody is shaping that canal with a single file.

Small canals with significant curvature or constriction cannot be shaped with a single file without risk of instrument separation, and canals with larger apical diameters will usually require two instruments — one to cut an initial shape so that the terminal diameter of the canal can be accurately gauged and the second file to finish.

With GTX Files, 95 percent of canals can be shaped with one to two files in less than a minute and half of all medium sized canals (in large molar roots) are completed with just one 30-.08 GTX File. Using any existing rotary handpiece and a technique you are familiar with. So this new “single-file shaping” claim is neither new nor true.

So what do you bring in and what do you leave out? The biggest improvement happening in my clinical practice is the introduction of full rotary negotiation. And for this giant step forward you don’t need a new handpiece; as these files work well in the handpiece you are currently using.

So two things to keep in mind here: First, if it ain’t broke, don’t fix it; and second, be certain before you make the investment to buy into a new rotary shaping system that it solves a problem that you actually have.

Editorial Note: This article was originally published in Endo Tribune U.S. Edition, Vol. 6 No. 8, August/September 2011.

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