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.

NanoEndo and Stellar Studios Awarded Gold Communicator Award for

NanoEndo is proud to announce its website,, has been awarded a Gold Communicator Award from The Academy of Interactive and Visual Arts. The website was developed in conjuction with Stellar Studios, a multimedia marketing agency based in Johnson City, TN. The Gold Communicator Award falls within the Websites, Websites Visual Appeal category and recognizes for its unique design characteristics and overall esthetic appeal.

“We really wanted to create something different that stands out from our competitors. My father and business partner, Dr. McSpadden, is distinguished as one of the world’s foremost endodontic file designers and he considers the One Endo file to be the best overall file design he’s ever seen. When we founded NanoEndo LLC to bring the One Endo file to market, I knew that our website would become the cornerstone of our efforts and I wanted its design to highlight the same uniqueness in thought and attention to detail evident in my dad’s instrument design. I have a long history of working with Stellar Studios to create award winning multimedia designs and it was a forgone conclusion that they would help us achieve our goals. Stellar Studios is an outstanding agency with tremendous talent and we are very fortunate to count them among our friends and partners.” – JT McSpadden, Chief Operating Officer, NanoEndo LLC

The Communicator Awards is the leading international awards program recognizing big ideas in marketing and communications. Founded two decades ago, The Communicator Awards receives over 6,000 entries from companies and agencies of all sizes, making it one of the largest awards of its kind in the world. The Communicator Awards is sanctioned and judged by the Academy of Interactive & Visual Arts, an invitation-only group consisting of top-tier professionals from acclaimed media, communications, advertising, creative and marketing firms. AIVA members include executives from organizations such as Airtype Studio, Big Spaceship, Conde Nast, Coach, Disney, The Ellen Degeneres Show, Estee Lauder, Fry Hammond Barr, Lockheed Martin, MTV Networks, Pitney Bowes, rabble+rouser, Sotheby’s Institute of Art, Time, Inc, Victoria’s Secret, Wired, and Yahoo!


K3 : Tip Evaluation (1st 3mm)



FILE NAME: SybronEndo
COMPANY: SybronEndo
MADE IN: Mexico



SIZE: 25/04
FLUTES: 3 (asymmetrical)
HELIX ANGLE: 31º [fig. 2]
60 ̊ DEFLECTION: 3.86 g



  • While the K3 has excellent side cutting ability, it is one of the least flexible files. Consequently, the K3 file is best used to enlarge the coronal aspects of a canal or for preparing straighter canals.
  • The minimum rotation to failure is noticeable. However, it should be noted that a file rotating at 500 rpm will complete 3 revolutions in less than 1/4 of a second and no file we’ve tested yet has withstood 3 full rotations without separating.
  • Peak torque at failure is a more important consideration and the K3 compares favorably to other files.




Fig. 1

Fig. 2











On Communication and Collaboration for Advancing Endodontic File Design

While the overwhelming majority of comments we receive regarding our research and innovations is very positive and complementary, publishing our independent research while marketing our own endodontic file designs and claiming unbiased objectivity opens us up to criticism and scrutiny. We expect and welcome such skepticism as it inspires discussion and informs further investigations. Our hope is that our openness to criticism and our transparency in operations will ultimately serve to balance biases and provide an open dialogue wherein all perspectives may be granted equal consideration. To that end, please consider the following comments we’ve received regarding our most recent series of endo file evaluations alongside our responses to them:

Alex’s Comment: (background unknown)

Great job Dr. McSapdden! Your experiment’s design proved that your file is the best! Well done!! Now it’s time to put together an experiment to prove that your children are the cutest!! Come on man! Is this a joke? How can you sell a file and test competitor files? Well. Thanks for wasting my time reading this commercial.

Dr. McSpadden’s Response:

The instant formula for failure may be to try to please everyone but we try. We try by using equipment that can give results that can be consistently replicated independent of the operator. We try with a commitment to publishing the results without knowing in advance what the results will be. We try by inviting any change in the parameters we use for testing as well as inviting anyone to observe the results as they occur. We try by including 35 years of our past testing experience to provide the most useful information we know how. We try by using the information we have accumulated to design instruments that might help in providing solutions for clinical needs. We try by having our quest for solutions to be a continuing endeavor. We try by convincing ourselves that trying is better than doing nothing when success is unknown but that even failure might be at least some benefit. And, we will try to help you find solutions if you should ask and hope that you might try to do the same for us. And, yes my grandchildren are the cutest and, as a 75 year old grandfather who doesn’t need to sell files, I will admit that particular claim might be biased.

David Clement’s Comment: (UTHSC Grad Endo)

This is a great project you are sharing with the Endo Community.  I look forward to seeing further results which you say will be distributed regularly. Just one comment, and perhaps a description criteria you could consider adding to the Descriptive Characteristics. The Circular core dimension as a percentage of the circumferential size (diameter) would be a very interesting characteristic to see.  The bulk of metal in the core (Not including the exposed cutting edges) could give fundamental information/understanding on torsional strength and and Cyclic fatigue characteristics of these rotary files.  It would also give information is the core area changes in the length of the blade, theoretically increasing the Flute space ( debris removing area). Again, Many thanks for sharing the project information with us. 

Dr. McSpadden’s Response:

…I think your idea is excellent. It might be good to carry it a step further and have the core as a percent of the total x-sectional area. If we cannot change the program easily I can include it in the discussion. I really appreciate your interest and comments.

If you have any questions or comments of your own, please feel free to share them with us however you like. Post them here, send us an email or give us call (844) ONE-FILE [663-3453]. We value your input and perspective and hope you will help us in collaborating for the advancement of endodontics.