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Endo Questions for the RWE Faculty:

In this area, users are encouraged to ask questions from the RWE Faculty regarding Endodontics in General and the EndoSequence Technique.

Endo Questions for the RWE Faculty:: Reciproc vs Rotary study showing more cracks on rotational motion

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Joined: October 2017

Rank: Sergeant

Posts: 5

#1
Dental Materials Journal 2017; 36(3): 243–252

The incidence of dentinal cracks during root canal preparations with reciprocating single-file and rotary-file systems: A meta-analysis
Xi WEI1,2,3*, Bo HU2,3,4*, Haiyang PENG1,2,3, Ming TANG1,2,3 and Jinlin SONG2,3,4 

I recently read this journal of analysis on reciprocating file systems vs rotational and wanted to clarify if I am missing something about this journal, from what I gather, the RWE approach is mostly rotational because it would cause less apical extrusion of debris and product less dentinal cracks but this journal seems to state the opposite.

Would love to hear a response from RWE about the validity of this journal and if this changes anything about the RWE approach. 
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Joined: July 2013

Rank: Officer

Posts: 27

#2
In reply to Stanley John I'll pass along the message to Dr. Nasseh to see what he thinks about this article. 
Allen_ali_nasseh

Joined: August 2013

Rank: Faculty General

Posts: 266

#3
In reply to Stanley John Hi there! If you have a copy of the article I can check it out. The fact that the article is published in Dental Materials Journal vs. Journal of Endodontics (a more relevant and higher quality journal) tells me something. As you said, logic tells us that incremental cutting creates less pressure than large volume cutting. Unfortunately, not all research is properly designed or makes sense. This is a meta analysis and while it appears of high evidence based quality it's only as good as the articles it chose to analyze. The fact that some articles contradict other articles shows that some are incorrect, since the same concept can not simultaneously be correct and false under similar conditions. This only indicates poor study design. Either way, in this case, reciprocation motion works, but single file reciprocation does put lots of pressure on the dentin since the operator has to use lots of pressure on the file. If you've actually used both systems like I have, you can immediately tell in which system you have to push with greater force to advance the file. There's no question you have to push much more with reciprocation than rotation if you want to achieve similar efficiency. If you only have a Master single file in a thin canal then pushing is even greater since a singe file does not naturally advance and you have to push it pretty hard to make it move forward. It's empirical is you use both rotation and reciprocation in two identical canals.  
Cheers!
Img_20171221_192838_330

Joined: October 2017

Rank: Sergeant

Posts: 5

#4
Allen_ali_nasseh

Joined: August 2013

Rank: Faculty General

Posts: 266

#5
In reply to Stanley John Thanks for sharing that link. I'll check it out over the holidays. The key here with all meta-analysis studies is that the conclusions are as good as the articles included in the analysis. While assessing micro cracks on dentinal surfaces is difficult to measure, it's much easier to measure the relative stress on the walls using different techniques by using optical stress analysis (like we do for posts). Using that measure there's no question that single files will produce more torque on the walls (and on the file) than distributing the cutting among serially rotary, or even serially reciprocating files. It's basic physics/kinematics. Either way, if the clinical effect is marginal, then a larger sample size may be required to find clinical significance. Unfortunately, that's what we lack in all endo studies. The n= is always too small to provide adequate power for our studies and account for the great variability of teeth clinically.
Clinically, you have to push on rotary files while you have to pull on the rotating files. This significantly greater pushing force should technically translate into more force in susceptible teeth. If you have you used both rotation and reciprocation in the same exact block you quickly realize how much harder you have to push when using single file reciprocation if you want to achieve similar efficiency as rotation. With rotation, your apical pressure should be the same you use on a sharp pencil. With Single File Reciprocation it's the same pressure you use on a ball point pen that's out of ink!!! 
But if this technique works for you and you like it then use it. Ultimately, instrumentation is only part of your success. More important factors are at play to determine the case outcome than the motion of instruments while shaping. Anyway.  
Have a good day! :) Al.