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

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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.

Vortex Blue : Tip Evaluation (1st 3mm)

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DETAILS:

FILE NAME: Vortex Blue
COMPANY: Dentsply Tulsa Dental Specialties
MANUFACTURER: Dentsply Tulsa Dental Specialties
MADE IN: USA
WEBSITE: tulsadentalspecialties.com

 

CHARACTERISTICS:

SIZE: 25/04
FLUTES: 3 (triangular)
SPIRALS PER 16MM: 4
HELIX ANGLE: 23º [fig. 2]
CUTTING ANGLE: (-)34º [fig. 1]
DEBRIS REMOVING AREA: 45% [fig. 1]
ROTATION TO FAILURE: 510º
PEAK TORQUE AT FAILURE: 63.08 gf/cm
60 ̊ DEFLECTION: 2.16 g
PLASTIC DEFORMATION: 0º
FILE CORE AREA RELATIVE TO CIRCUMFERENCE AREA: 55%
FILE CORE AREA RELATIVE TO FILE X-SECTION AREA: 69%

 

DISCUSSION:

  • Most interesting from the results of testing is the difference in properties of the Vortex Blue compared to those of the Sequence file; especially since both have the same cross-sectional configuration and helix angles. Contrary to the manufacturer’s claims, the Vortex Blue’s resistance to torsion was not enhanced, but instead appears to be substantially less than that of the Sequence file.

 

TIP SEM

TIP SEM

Fig. 1

Fig. 2

 

 

 

 

 

 

 

 

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K3 : Tip Evaluation (1st 3mm)

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DETAILS:

FILE NAME: SybronEndo
COMPANY: SybronEndo
MANUFACTURER: SybronEndo
MADE IN: Mexico
WEBSITE: sybronendo.com

 

CHARACTERISTICS:

SIZE: 25/04
FLUTES: 3 (asymmetrical)
SPIRALS PER 16MM: 7
HELIX ANGLE: 31º [fig. 2]
CUTTING ANGLE: VARIES [fig. 1]
DEBRIS REMOVING AREA: 34% [fig. 1]
ROTATION TO FAILURE: 270º
PEAK TORQUE AT FAILURE: 89.87 gf/cm
60 ̊ DEFLECTION: 3.86 g
PLASTIC DEFORMATION: 0º
FILE CORE AREA RELATIVE TO CIRCUMFERENCE AREA: 66%
FILE CORE AREA RELATIVE TO FILE X-SECTION AREA: 58%

 

DISCUSSION:

  • 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.

 

Tip SEM

TIP SEM

Fig. 1

Fig. 2

 

 

 

 

 

 

 

 

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