Cents and sensibility

X-ray taken by Dr. HB Johnson circa 1939 (courtesy Dr. Tom McDonald, Atlanta GA)

X-ray taken by Dr. HB Johnson circa 1939 (courtesy Dr. Tom McDonald, Atlanta GA)

When preparing a root canal, there seems to be nothing that can’t be achieved by a skilled endodontist. In the right hands, virtually any root canal can be prepared with virtually any file or number of files. The very small curvature radius and large curvature angle in the featured x-ray illustrates the extraordinary skill for using carbon steel files in 1939 by Dr. H.B. Johnson, the individual that gave us the term “endodontics.”

Curiously, it is rare that a file is promoted today without an accompanying x-ray depicting an extraordinarily difficult case. Should we conclude then that all files will enable you to achieve ideal root canal preparations? We can eliminate almost all restrictions except for one, our inability to freeze time. Ahh… there’s the rub. Time is our most valuable commodity.

Many years ago, a clever sales rep showed me a time saving formula demonstrating the annual money savings that a very expensive digital x-ray device would provide before convincing me to buy what turned out to be the very first digital x-ray device sold in the US. Ever since, that formula has continuously convinced me that penny-pinching at the expense of saving time isn’t really saving money at all. It’s no different with endodontic files. Consider that by saving 10 minutes/patient with each of 6 cases/day for 200 days results in 5 weeks of chair time saved annually. That’s more than a month of additional production, vacation or whatever you like!

A file’s ability is not the issue. Rather, a file’s efficiency during performance is THE most important issues and our guiding objectives when designing NanoEndo files. Our results are extremely successful in this regard and our customers agree that NanoEndo’s highly efficient designs save them time and reduce risks during root canal preparations. See for yourself and review our comparisons with the files you are using now or give us a call (844.ONE.FILE) to learn more. Remember lost time can never found.

Is scientific hype replacing scientific evidence?



**Watch this VIDEO to see a brief summary on how results from our testing of file performance differs from conventional testing of flexibility and cyclic fatigue.**

Many endodontists have devoted a great amount of valuable time to endodontic instrumentation research using scientific evidence in an attempt to convey useful information for the advancement of endodontics. Scientific evidence relies on comprehensive data and it is crucial for researchers to ensure that the data they collect is sufficiently inclusive to have relevance to actual clinical situations. When “scientific hype” reaches the point that it diminishes the value of scientific evidence, then practitioners need to be aware that insufficient information can have counterproductive consequences.

During scientific research it is not uncommon to encounter hype. Although somewhat frustrating, common hype is usually tolerated because claims are at least somewhat true. Even though the benefits of the claims are usually exaggerated, they are transparently limited in scope. An example of such a claim would be: “These files are faster, safer, and require fewer sizes.”

What is apparent to the dentist is the missing ‘compared to what’ or ‘under what circumstances’. Taken alone, these claims are obviously discounted as scientific evidence. Recently, however, a more insidious hype, one that uses insufficient and selective scientific testing, has lead to erroneous conclusions and created an opportunity for mistakes. This type of hype uses the convincing nature of inductive reasoning that is not so apparent, but may be easier to recognize once it’s broken down into logical propositions. Consider the following examples:

From a specific proposition such as:
A file’s greater resistance to cyclic fatigue is better than less resistance to cyclic fatigue.

To a general proposition:
Greatest resistance to cyclic fatigue results in the best file.

This particular general proposition has gained widespread acceptance and success in the promotion of endo files. One company claims, “700% greater fracture resistance compared to traditional NiTi files” without stating that the increased resistance to cyclic fatigue was accompanied by a reduction in the resistance to torsional stress, an essential component of resistance to failure. Another company uses resistance to cyclic fatigue as evidence for “unmatched strength”, “Off the charts Strength,” “Amazing strength means the confidence…,” and “Twice the strength, half the cost.”

The definition of strength within the context of metallurgy is the resistance to deformation. Now consider that the files described above distort with the least force of almost all, if not all, of the files on the market. All other factors being equal, increasing the resistance to cyclic fatigue is concurrent with a decrease in file strength and resistance to torsional stress. Unwinding is evidence of torsional stress. The question becomes, as long as the resistance to cyclic fatigue is adequate, why compromise by reducing the resistance to torsional failure?EdgeVsOneEndo_Graphs

There are certain features of science that give it a distinctive character as a mode of inquiry. Once that mode of inquiry is compromised, It is no longer valid science. When a company claims that its file will rotate over 600 seconds in a 90 degree curvature 3mm from its tip, and that capability is two times as long as a competitive file, does it make it a better file? If it does, does that mean a copper wire of the same diameter that will rotate 1,800 seconds is the better file? Actually, it only means that it has better resistance to cyclic fatigue in that particular circumstance with no evidence for superior performance. Besides, who lets a file rotate 600 seconds in a 90 degree curvature? Or even 10 seconds? Is there relevance to actual clinical situations?!

The ultimate goal for instrumentation advancement can be stated as, ‘maximizing efficiency and minimizing risks while accomplishing the preferred results.’ How effectively that goal is achieved is a measure of performance. My hope is that you will scrutinize all claims of advancement to the best of your ability. That especially pertains to any claims that I might make. Scrutiny is the hallmark of advancement.


Limiting Torsional Stress on Endodontic Files: Lubrication, Irrigation and/or Technique


I was recently asked if irrigation and lubrication influenced the stresses a file undergoes during instrumentation. Research that I carried out indicated irrigation and lubrication can reduce torque requirements by as much as 400% compared to rotating in a dry canal. However, one can see from the included chart that the amount of the file’s engagement can be as important as the lubricant itself in reducing torsional stress. Shorter strokes of insertion is more effective in reducing torsional stress than carrying the rotating file to greater depth into the canal with fewer insertions. When the rotating file becomes engaged for more than a very few millimeters, the interface of irrigation is reduced between the surface of the canal and the file and torsional stress increases.


The importance of engagement is illustrated. Quantec files were inserted in 1mm increments at 1mm/s with a depth of 8, 10, and 12mm. The torque recorder is an average of 6 files taken for each depth. Note minimum engagement can have approximately the same benefit as irrigation in reducing torque.

Conventional Research: Greater Value than Actuality?

Screen Shot 2015-11-09 at 9.08.49 AMAfter so many years of research, it is daunting to succumb to the realization that so much of my time was devoted to compiling conventional, or what could be considered useless, data for evaluating endodontic files. Someone once commented, “There is no ox so dumb as the orthodox.”

For instance let’s consider a file that is statically in the 50 percentile compared to other files in resistance to cyclic fatigue and also in the 50 percentile (50/50) in resistance to torsional failure. Research will reveal that files that are in the same percentiles can perform very differently. Compiled data for these percentiles might give little indication as to how a 60/40 percentile would perform  or a 40/60 percentile. Certainly a 100/? percentile can amount to little more than hype. There are too many other design differences to consider for extrapolating for conclusions.

My realization from the research I have experienced is, file features should only be considered file features with no indication of how the file will perform until performance itself is measured. Only then, should we attempt to explain the performance in terms of the file’s features. We can use the “ox“ depiction again to represent the paradox of Schrodinger’s cat; we have to see the results first to explain them and then our explanations might actually be very comprehensive.

Fortunately, we at NanoEndo have conducted literally 100s of file evaluations measuring performance, probably more than all other performance evaluations put together. And, fortunately, you do not have to depend on projections. NanoEndo files speak for themselves; their performance excels beyond comparison. We invite you to see for yourself.

Join Us for a Complimentary Seminar

The Efficient and Productive Endodontic Practice:  Dr. JohnT.McSpadden

If you save a penny and double it every day, it only takes 27 days to become a millionaire. We are familiar with the power of compound returns but sometimes the power of accumulative returns escapes us, particularly in our practice. Ponder this as an endodontist: If you complete 6 cases a day and if you save 10 minutes for each case for 50 weeks, you would “save” over 31 eight hour work days in a year. If not saved, perhaps “wasted” is a more accurate term.

I became so impressed with the accumulative returns concept that my practice became a laboratory for developing proficiency. That involved collecting ideas from scores of practices for over 40 years and designing over 30 patented files and techniques for efficiency to become one of the most productive practices in the nation. The potential gains when you maximize how efficiently you perform can be astronomical. Nothing, however, has given me more satisfaction than being able to learn from your and others’ expertise and to combine them with my unique experiences in the form of seminars.

We condense the NanoEndo seminar to 1 concentrated, full day for developing all aspects of practice efficiency, but especially on how files and preparation techniques can dramatically and uncompromisingly provide “accumulative” returns. Conversely, we point out that one might spend way too much time on things that don’t matter.

Our approach:

  • First an examination of the sequence of file development will be used to recognize what and why file features and seminar-imagetechniques constitute advantages and disadvantages.
  • Determine and test for time/risk benefits and limitations of any file and technique.
  • Determine when to use fewer or more files during canal preparation for results and time conservation.
  • Determine a file’s limitation and maximize its capability.
  • Determine the appropriate files and technique to use relative to the canal anatomy.
  • Determine how to minimize stress and maximize efficiency during canal preparation.
  • Discover how the files and techniques you now use compare with the alternatives while using the computerized clinical simulator.
  • Discover how to practice at the speed of thought; there are no “cookbook”step by step procedures.
  • Learn how to reduce the things that “don’t matter”.
  • Learn how to use a formula to identify and use “accumulative” returns in all aspects of your practice from the “hello to the goodbye” of patient treatment.

Our objective is not to tell you what to think or even being an advocate, but rather to help in making discoveries. We invite you to join us for the Nov.13, 2015 COMPLIMENTARY Seminar, but let us know soon to best accommodate you. Email or call us directly at 844.ONE.FILE (844.663.3453).

Our seminars are held in Chattanooga, Tennessee, one of the South’s top travel destinations. In fact, the New York Times named Chattanooga one of the “Top 45 Places to go” in the World.  Only four US destinations were named and the Scenic City was the only place outside of California.  And it’s no wonder, tucked away between the mountains of Southeast Tennessee and along the beautiful Tennessee River. We hope you will decide to bring your family and spend some time here. http://www.chattanoogafun.com/

Direct comparisons of a singular NiTi file design with and without heat treatment


The physical properties of nickel titanium endodontic files that are heat treated for enhancing flexibility differ so widely that definite correlations are difficult to determine. This is particularly true when there are no controls for heat treated files having the same design dimensions. D&S Dental, LLC provided identical files having different degrees of heat treatment for testing and determining correlations. One group of files had no heat treatment (Group A), one group had medium heat treatment (Group B) and one group had greatest heat treatment (Group C). Each group was tested for rotation until failure (suspended at 3mm from tip), peak torque at failure, and force required for 5mm deflection on a 60 degree inclined plane to measure tip flexibility. Group A, no treatment, values were used as base lines for comparisons.The results are as follows:


Group B Group C
Degrees Rotation to Failure (+)61% (+)33%
Peak Torque at Failure (-)7.6% (-)69%
Force on 60 Degree Incline (-)12.5% (-)26.6%


Although there is an approximate direct correlation for peak torque at failure and force for 60 degree incline flexibility, the degree of rotation to failure appears to be an aberration of expectation. Within the scope of this limited research, we can conclude that heat treatment applied to enhance flexibility will accompany a decrease in resistance in torsional stress.

EXO Endo File Impresses Southeastern Endodontics’ Dr. Brock

Courtesy of Matthew Brock, DDS, MSD

Courtesy of Matthew Brock, DDS, MSD

Shortly after sending him his first packs of EXO Endo files, we received this outstanding feedback from Matthew Brock, DDS, MSD of Southeaster Endodontics:

“After cleaning and shaping the canal system for this tooth I was able to feel that the apex was a size 35 to 40 with .02 tapered instruments.  After a 30/.06 EXO File went to length with great ease, I opened the apex to a 40/.02 & then followed with a 35/.06 EXO File without issue  (in a 78 degree curvature with a fulcrum pt. of curvature 8mm from the apex, the diameter of the EXO 35/06file the would be .83mm).  The EXO File is incredibly flexible when compared with other files on the market.  If you had told me I would take a 35/.06 to the apex of a MB root just a few years ago I would have imagined a hogged out canal with no flow, and in the case of this tooth I would have seen disaster written all over it.  The EXO File negotiated the canals effortlessly and will remain in my armamentarium.”

We appreciate Dr. Brock taking his time to let us know about his experience using EXO Endo files and hope you can find the time to try them for yourself. And if you feel you don’t have the time to try our files yourself, it just means you can’t afford not to.

If a picture is worth a thousand words, then what’s that worth?

X-ray taken by Dr. HB Johnson circa 1939 (courtesy Dr. Tom McDonald, Atlanta GA)

Most of the time x-rays of tortuous canals are used to demonstrate the capabilities of a file. This begs the question: exactly how much information do we get from an x-ray. Dr. HB Johnson, one of the pioneers of endodontics and the man who coined the term endodontics, is the person that performed the RCT of the featured x-ray taken around 1939. If we use this x-ray (courtesy of Dr. Tom McDonald, Atlanta GA) illustrating a successful end result as a benchmark, then we shouldn’t be so impressed with x-rays portrayed today as an indication of how good a file is. The files he used were carbon steel, worse than any file than most of us have ever seen. I’m including two x-rays of cases I completed soon after the introduction of NiTi rotary files. I cannot even remember which files were used, but probably not the ones I would recommend today.  The point is: virtually any file can prepare virtually any canal. More difficult to illustrate is the ease, predictability, and productive capability of a file. This is why our research focuses on determining endo file limitations and efficiencies rather than endo file abilities, given the time and skill of the operator.

What difference does unwinding an endodontic file make if it doesn’t break?

extrusion segI was recently asked why would it matter if an endodontic file unwound as long as it didn’t break. First, let us think of a file as not only an instrument that enlarges a canal but one that acts as an auger as well; it conveys debris. When a file unwinds to the extent that its helix augers apically rather than in a coronal direction (as in segment 1), then debris is extruded through the apical foramen. Note that part of the file becomes denuded. Post operative pain will most likely be the consequence. The unwound segment 2 continues to auger debris in a coronal direction while the unwound segment 3 augers in an apical direction. The result is compression of debris, additional torsional stress and a greater propensity for breakage. Keep in mind most files will not even unwind 2 revolutions without fracturing. If the file is rotating 500rpm, 2 revolutions require less than 1/4 second before failure.

The short answer to the question is: it probably matters. Luck is not nearly as predictable as cause and effect.

Maximizing Efficiency – for what it’s worth


Time is the one commodity shared equally with all. No matter who we are or where we are we each get 60 minutes with every hour, 24 hours each and every day and then it is gone forever. One cannot keep time from passing, yet, profoundly, one can save time.

Early in my career, I had the good fortune to enroll in a course on ergonomics. The curriculum was about efficiency and how best to streamline all the individual movements and methods used to complete a procedure. This concept resonated with me and guided my thinking and methods throughout the rest of my career. In fact, my endless pursuit of efficiency within my own practice is what ultimately inspired me to design and modify my own instruments and techniques.

Even very small gains in efficiency will compound over time and can have a profound impact on a practice over the course of a career. Suppose you could save 10 minutes with each patient. If you see only 6 patients in a day, that would equal an extra hour each day; 5 hours each week; 260 hours each year. That’s the same as 32.5 eight hour working days a year! Can you imagine that a simple 10 minute gain in efficiency might result in gaining an entire month’s worth of time over a year? What is the value of such a proposition? Keep in mind that there is a big difference in saving time and wasting time.

In my practice, I bought and tried every new gadget that came to market, always searching for new ways to save time and effort. Mine was one of the first practices to use digital x-rays, electric handpieces and a microscope. Later, I introduced a NiTi rotary file simply because I knew it would make me more efficient. Ultimately, I became so efficient that I had even more time to seek out even greater efficiencies and now that I’m retired from practice, the fascination remains.

The One Endo file’s design was born from my unending pursuit of maximizing efficiency in instrumentation and my research continues to validate that combining two or more dissimilar tapers side-by-side within the same instrument, significantly enhances virtually any endodontic file design. Recently I was asked to describe why an established practice should consider switching file systems to incorporate the One Endo file in terms of a return on investment. Addressing any ROI demands that benefits are quantified, so I turned to data from our research for insight.

What I found when taking a very broad view for comparison was striking: the One Endo file is 33% more efficient on average than every other file we’ve tested to date. This number is a comparison of the average maximum torque and pressure values from all files and sizes tested with our Endo File Evaluator against the same parameters for all sizes of the One Endo. More importantly, it should be noted that half of our competitors’ files failed their respective evaluations resulting in broken/distorted tips or screwing into or transporting the canal.

While this finding does not mean that switching to the One Endo will save you 33% more time or money, it does mean that it is very likely to allow you to complete the same amount of work with less effort. Depending on how you adapt your technique to incorporate such a gain in efficiency, this could result in time/money savings, but most importantly, it is likely to improve your results. This poses a new question: If you can become more effective by using a new file, why wouldn’t you try it? Remember that 10 minutes I saved way back when? Consider this – at the end of my 31 years of practice, those 10 minutes managed to free up over 2.5 years of extra time! Granted, I can’t tell you where that time went, but it wasn’t wasted and I loved every minute of it.