Is scientific hype replacing scientific evidence?

EdgeVsOneEndo_Pics

 

**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.

 

EdgeEndo : Tip Evaluation (1st 3mm)

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DETAILS:

FILE NAME: EdgeFile
COMPANY: EdgeEndo
MANUFACTURER: MicroMega
MADE IN: France
HEAT TREATED IN: United States by US Endo
WEBSITE: edgeendo.com

 

CHARACTERISTICS:

SIZE: 25/04
FLUTES: 3 (triangular)
SPIRALS PER 16MM: 6
HELIX ANGLE: 26º [fig. 2]
CUTTING ANGLE: (-) 40º [fig. 1]
DEBRIS REMOVING AREA: 60% [fig. 1]
ROTATION TO FAILURE: 1002º
PEAK TORQUE AT FAILURE: 51.13 gf/cm
60 ̊ DEFLECTION: 1.62 g
PLASTIC DEFORMATION: 7º
FILE CORE AREA RELATIVE TO CIRCUMFERENCE AREA: 32%
FILE CORE AREA RELATIVE TO FILE X-SECTION AREA: 60%

 

DISCUSSION:

  • Although the file is very flexible, its resistance to torsional stress is very limited. Plastic deformation occurs with comparatively minimal force.
  • The tip is blunt and will not negotiate a canal having a smaller diameter without burnishing its way into the canal and resulting in greater torsional stress.
  • The large number of spirals requires debris to be conveyed a greater distance and increases the EdgeEndo’s tendency to screw into the canal. Both factors contribute to increasing torsional stress.

 

TIP SEM

Fig. 1 : TIP X-SECTION

Fig. 2

 

 

 

 

 

 

 

 

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Introduction to Mastering Endodontic Instrumentation : An online addendum

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What differences do design differences make? We intend to find out. We are embarking on a very ambitious research program to test each part of every major file in production, from tip to handle. We have completely up-dated the computer controlled Endo File Evaluator to improve resolution of its sensors and motors and to expand its capability for performing new testing protocols. As such, we have created what I believe is not only the most objective means for evaluating endodontic files, but also the best method for testing file functions in a manner that is truly relevant within a clinical setting. We do this while letting the data determine the results for objective comparisons independent of operator skill or marketing bias.

What difference does this endeavor make? Our first objective is to finally determine how to minimize risk and maximize efficiency, how file designs relate to function, how function relates to canal anatomy, and how anatomy relates to technique. Our second objective is to present the Endo File Evaluator results using the numerous different parameters for testing, and to use high resolution images and SEMs in a manner that allows clinicians to save and apply the information to enhance their skill and treatment.

How will this process take place? About every ten days we will share test results and observations of only one segment of each file beginning with the file tips. Through this blog, we invite you to participate in discussions and critiques to create group research dynamics as this project progresses. Once all segments of the files have been covered, a composite of each whole file will be available as an endodontic reference along  with any contributing assessments gathered from our readers. We will continue providing results as we find them through this comprehensive series of evaluations and add to them in the future as needed. We are excited to embark on this endeavor and hope you will follow along and contribute your own thoughts and impressions.

 

DOWNLOAD MASTERING ENDODONTIC INSTRUMENTATION (original award winning text)

 

What differences do endo file design differences make?

Screen Shot 2015-02-04 at 7.24.00 PM

What differences do design differences make? We intend to find out. We are embarking on a very ambitious research program to test each part of every major file in production, from tip to handle. We have completely up-dated the computer controlled Endo File Evaluator to improve resolution of its sensors and motors and to expand its capability for performing new testing protocols. As such, we have created what I believe is not only the most objective means for evaluating endodontic files, but also the best method for testing file functions in a manner that is truly relevant within a clinical setting. We do this while letting the data determine the results for objective comparisons independent of operator skill or marketing bias.

What difference does this endeavor make? Our first objective is to finally determine how to minimize risk and maximize efficiency, how file designs relate to function, how function relates to canal anatomy, and how anatomy relates to technique. Our second objective is to present the Endo File Evaluator results using the numerous different parameters for testing, and to use high resolution images and SEMs in a manner that allows clinicians to save and apply the information to enhance their skill and treatment.

How will this process take place? About every ten days we will share test results and observations of only one segment of each file beginning with the file tips. Through this blog, we invite you to participate in discussions and critiques to create group research dynamics as this project progresses. Once all segments of the files have been covered, a composite of each whole file will be available as an endodontic reference along  with any contributing assessments gathered from our readers. We will continue providing results as we find them through this comprehensive series of evaluations and add to them in the future as needed. We are excited to embark on this endeavor and hope you will follow along and contribute your own thoughts and impressions.

How to Interpret Graphs from NanoEndo’s Endo File Evaluator

View the test at http://nanoendo.com/evaluator-v2.php

View the test at http://nanoendo.com/evaluator-v2.php

What do the graphs we display provide to us as beneficial information that can be used to enhance our instrumentation expertise? Generally speaking, as long as the plotted coordinates remain within the grid boundaries, the file is suitable to be used with the parameters specified in a canal with identical dimensions and properties if the file did not distort, break or excessively screw- in. That may sound like too many limitations to consider, but the trial run in practice blocks offer surprisingly relevant information clinically.

As an example, let’s take a look at the graph above for the Edge file 20/06. First we note that the tip distorted, although positive coordinates (points above base line zero) do not seem alarmingly high. We only have to consider positive measurements for torque because this is this is the only stress for torsion that will cause distortion. Negative pressure, on the other hand, indicates the screwing-in factor. Negative readings exceeding -2lbs should be a matter of concern (note the reading at 11:46:06 where the measurement is more negative than -2). Remember in this situation the device automatically reverses after 1mm of advancement. Manual reflexes might not be as quick since screwing-in forces are more insidious. Note also, the spike in negative pressure was accompanied with a spike in torsion and both occurred early in the cycle. It is at this point that the tip probably distorted.

What does this information tell us if we are to use this file? It means that we should be careful to limit the progress of advancement into the canal with very short pecking motions and to exercise caution with each insertion to counteract any sudden screwing-in forces. In addition, we should check for distortion frequently.