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.

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

  1. Would like to read your extensive research and methodology on endodontic files. I think each root canal case is unique and its difficult to pin down a uniform BMP protocol for all. Endodontic files will keep on evolving in illusive quest for perfection. Perfection is in deciding the right file at the right time of clinical procedure.

    • Thank you for your interest and I absolutely agree with your assessment. So many of what I call “cookie cutter” type techniques are promoted by endodontic file manufacturers and none of them take into account the infinitely different anatomies we will encounter throughout our careers. Here is a LINK to the webpage where Mastering Endodontic Instrumentation is available for download. I hope you find the text useful and welcome your questions and discussion as you explore it. Thank you again and I hope to hear from you soon.

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