Size of Apical Instrumentation

Shaping and Cleaning or just shaping ? (credits- Prof Senia)

I am expressing my personal thoughts about final apical preparation sizes because I feel obligated to do so. As a former professor who treated many patients and taught many endodontic postdoctoral students for many years, I was dedicated to science and truth. I was able to do that because during my career as an Air Force Endodontist, and later as a University Dental School Professor, I was never paid for any treatment rendered to my patients. Since I was blessed in never having to be concerned about “money”, all my attention was dedicated to studying hard, searching for the truth, and giving my patients the best care possible.

I am very well aware of the pressures placed on the endodontic profession by the manufacturers of root canal instruments to promote small apical preparation sizes. (Because their larger sizes are not flexible enough?). I am also aware that some opinion leaders are also advocating small sizes with little to no scientific research for support. Because such beliefs are popular doesn’t mean that they are scientifically correct. Unfortunately, many endodontists blindly follow the leaders.

Now we are even being told that almost all canals can be prepared with a single instrument. What? Sure, a canal can be prepared with many different kinds of instrument systems—take your pick. However, endodontic science still dictates that the role of mechanical instrumentation is to clean a canal--along with irrigation, of course. Somehow, the word clean is not used very often now-a-days. Is it because instruments are shaping—but not cleaning?

Most studies have confirmed what is obvious and logical. Infected canal walls, carrying the heaviest burden of bacterial contamination, are best cleaned with larger (appropriate) size instruments by mechanically scraping the walls. How is this done with instruments smaller than the actual canal size? Remember the old belief that this can be done with circumferential filing? What a magnificent myth that was!

Measuring a canal’s diameter is not rocket science. The results of published studies are there for all to see—and hopefully heed. Apical canals do not have the small sizes that are presently claimed. But, we know that even nickel-titanium instruments become quite rigid above the smaller sizes. We also know that such rigidity causes transportation of canal walls, ledges, zips and other mishaps. So what is the solution? Simply advocate small apical preparation sizes and the problem is solved. And that is exactly what happened. Flexibility is key to properly cleaning canals with curves—which most canals are. That is why we developed LightSpeed instruments with that all important feature of flexibility.

I reviewed your cases and wish to compliment you on the quality of your documentation, radiographs, and especially, photographs. Your working lengths and final fills are radiographically very good. However, we know that they do not tell the whole story. They do not show that all canal walls have been cleaned nor that the canal is 3-dimensionally well obturated. Learn PROPER ENDO NOW

There is ample science to show that apical size should gauged and cleaned adequately for success of root canal treatment, See Additional documentation Tweet